COMPREHENSIVE MOSQUITO 

SURVEILLANCE AND CONTROL PLAN

 

2006 

The City of New York 

DEPARTMENT OF HEALTH AND 

MENTAL HYGIENE 

Michael R. Bloomberg 

Mayor

Thomas R. Frieden, M. D., M. P. H.

Commissioner
1

New York City Department of Health and Mental Hygiene

Comprehensive Mosquito Surveillance and Control Plan

2006 

TABLE OF CONTENTS

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 

Public Education and Community Outreach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 

Host Surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 

Human Surveillance and Provider Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 

Mosquito Surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 

Larval Mosquito Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 

Adult Mosquito Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 

Surveillance of Potential Adverse Health Effects from Pesticide Exposure . . . . . . . 25 

Research and Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 

Appendix A: Questions and Answers About West Nile virus . . . . . . . . . . . . . . . . . . 29 

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 
New York City Department of Health and Mental Hygiene 

2006 Comprehensive Mosquito Surveillance and Control Plan 

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New York City Department of Health and Mental Hygiene 

2006 Comprehensive Mosquito Surveillance and Control Plan

 

 

EXECUTIVE SUMMARY 

In 1999, New York City experienced an unprecedented outbreak of encephalitis caused 

by West Nile (WN) virus, a mosquito-borne virus never before detected in the Western 

Hemisphere. That year, 59 cases of neuroinvasive disease (encephalitis, aseptic 

meningitis or acute flaccid paralysis) due to WN virus occurred in the New York City 

metropolitan region. Since 1999, WN virus has reappeared in New York City each year 

during the adult mosquito season. A total of 137 human cases of WN neuroinvasive 

disease, including 17 deaths, have occurred among New York City residents from 1999-

2005. A small number of human cases of WN fever have also been reported (n=12), 

although the estimated number of undetected or unreported WN fever cases is much 

higher over the same time period. Over the past six mosquito seasons, WN virus has 

spread throughout much of the United States, causing large outbreaks of neuroinvasive 

disease in 2002, 2003, 2004, and last year was responsible for 2,949 human cases of West 

Nile infection in 43 states, 116 human deaths along with hundreds of horse and bird 

deaths.

The Department of Health and Mental Hygiene (DOHMH) has analyzed the previous 

year’s surveillance and control efficacy data in order to better prepare for the upcoming 

mosquito-breeding season. To ensure a coordinated approach in managing mosquitoborne disease outbreaks in the City, DOHMH has worked closely with the New York 

State Departments of Health (NYSDOH) and Environmental Conservation (NYSDEC), 

the U. S. Centers for Disease Control and Prevention (CDC), and other State and Federal 

partners, along with many local organizations. Several New York City agencies have 

been crucial to the planning process, including the Mayor’s Offices of Operations and 

Environmental Coordination, New York City Office of Emergency Management, and the 

Departments of Environmental Protection, Parks and Recreation, Sanitation, Police, 

Citywide Administrative Services, Information Technology and Telecommunications and 

the Housing Authority. 

Key to DOHMH’s planning efforts is a primary emphasis on prevention. DOHMH 

continues to devote considerable resources to a citywide effort to prevent mosquito 

breeding, while enhancing existing disease surveillance, and public and medical provider 

education activities. The goal of this plan is to prevent disease caused by mosquitoes 

through aggressive source reduction and larviciding. Should surveillance findings 

indicate that a substantial risk exists for WN virus transmission to humans, adult 

mosquito control will be considered. 

Surveillance data collected in 1999-2005 demonstrate that WN virus can be detected in 

birds and mosquitoes weeks before there is a significant risk to human health. Therefore, 

the tracking of dead bird reports, especially crows and other corvids, and the routine 

surveillance of mosquito populations provide the City the opportunity to specifically 

target those neighborhoods and communities where virus is reappearing. The goal of 

early detection is to enhance mosquito control in high-risk areas in an attempt to interrupt 
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the amplification of the virus before it has a significant impact on human health. 

Although mosquitoes are most active in New York City from May through October, our 

strong mosquito prevention, surveillance, and control efforts are year-round activities. 

The current Comprehensive Mosquito Surveillance and Control Plan is designed to 

minimize the impact of mosquito-borne diseases through citywide surveillance measures 

and an integrated approach to mosquito management with control practices that are 

commensurate with the risk posed by these diseases. The comprehensive nature of the 

plan ensures the efficacy of the control measures while minimizing adverse impacts to 

the environment and human health from these measures. The plan includes the following 

components: 

Public Education and Community Outreach

Through the media, advertising, presentations to community groups and collaboration 

with community boards and elected officials, the Office of Communications will increase 

public awareness of mosquito-borne disease risk, surveillance, prevention and control. If 

surveillance data indicate an increased human disease risk that requires the application of 

pesticides to control adult mosquitoes, accurate and timely information of these mosquito 

control activities will be provided. Communications will provide the public with 

application schedules, the type of pesticides being used and how to reduce exposure. 

Additionally, the public will be informed about what to do in the event of pesticide 

exposure. 

Host Surveillance 

Animals will be monitored for infection and illness, with a focus primarily on dead birds, 

especially corvids such as crows and blue jays and songbirds such as sparrows, robins 

and grackles. DOHMH’s Office of Vector Surveillance and Control (OVSC) in 

collaboration with the Office of Veterinary and Public Health Services (VPHS) will 

monitor disease among domestic animals, particularly horses. The public will be asked to 

report dead birds through New York City’s Citizen Service Center (311) and via 

DOHMH’s enhanced WN virus web site (nyc.gov/health). Broadcast alerts will be sent at 

the beginning of the season to all veterinarians in New York City. Veterinarians will be 

requested to report any suspicious animal cases with neurological abnormalities to 

DOHMH. All animals with neurological symptoms will be tested for rabies before being 

tested for WN virus. 

Human Surveillance and Provider Education

A system for detecting mosquito-borne diseases among humans will include passive 

surveillance for suspected cases of viral encephalitis and aseptic meningitis in hospitals 

and laboratories. Broadcast alerts will be sent at the beginning of the season and 

periodically throughout the season to all hospitals in New York City. Health care 

providers play a critical role in the detection, prevention and clinical management of 

mosquito-borne diseases. The Communicable Disease Program will continue its efforts to 

educate New York City health care providers regarding diseases transmitted by 

mosquitoes, especially WN virus, and encourage reporting of and testing of suspected 
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patients with encephalitis and other diseases possibly caused by arboviral infection. The 

DOHMH Public Health Laboratory will test blood and cerebrospinal fluid samples 

submitted by health care providers for WN virus and other mosquito-borne viruses upon 

request. 

Mosquito Surveillance 

DOHMH’s Office of Vector Surveillance and Control will monitor mosquitoes citywide 

by collecting larval and adult mosquitoes to determine the distribution, density and 

species. DOHMH will continue to test adult mosquitoes collected in New York City for 

WN virus at its own laboratories. With testing taking place locally, the time required to 

receive results showed significant reduction in 2003, 2004 and 2005. This has allowed 

for increased public education, more focused mosquito breeding reduction activities as 

well as more targeted control of larval and mosquitoes in area with increased viral 

activity. 

Larval Mosquito Control

DOHMH will reduce mosquito breeding through the aggressive elimination of standing 

water and the application of larvicide to sites that cannot be emptied or drained. Through 

a public information campaign, DOHMH will urge residents to reduce breeding sites 

around their homes and commercial properties and to report potential mosquito-breeding 

sites. DOHMH will collaborate with elected officials, other City agencies and large 

property owners to eliminate standing water in empty lots, tire piles and other containers. 

DOHMH will also aggressively enforce the health code that requires elimination of 

standing water from properties throughout the City. These activities will be augmented 

with the application of larvicide to potential breeding sites where water cannot be 

eliminated, including catch basins citywide. Whenever WN virus is detected in an area, 

DOHMH will increase public education, breeding site reduction and larviciding. 

Adult Mosquito Control

A timely and appropriate response to mosquito, bird, mammal and human surveillance 

findings is key for preventing an outbreak of human disease. DOHMH will implement a 

phased response to surveillance findings that will expand education, prevention and 

control activities in relation to the threat of an outbreak of human disease. If surveillance 

indicators suggest that the level of WN virus activity poses a significant threat to human 

health, adult mosquitoes will be controlled through the use of adulticides. Mosquito 

density and distribution, mosquito species, persistence of WN virus activity, weather, 

time of year, and the proximity to human populations will be carefully considered in 

determining the necessity for adult mosquito control. The accuracy, quality and efficacy 

of the adulticide application will be closely monitored to ensure compliance with Federal 

and State guidelines. If application of adulticides becomes necessary, DOHMH will 

provide advance notice to the public and to health care providers. 

Surveillance of Potential Adverse Health Effects from Pesticide Exposure

In 2001, DOHMH completed a comprehensive environmental impact study on the 
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pesticides used for adult mosquito control. The study concluded that at the relatively low 

levels at which adulticides are applied, the occurrence of adverse public health effects to 

the population from applying pesticides to reduce the adult mosquito population would not be 

considered significant when compared to the potential risk to the public health from West 

Nile virus or other mosquito-borne illness. However, health care professionals are 

informed and reminded throughout the mosquito season about potential health effects of 

pesticide exposure and the need to report pesticide-related illness to DOHMH and 

NYSDOH. DOHMH will monitor the adverse health effects associated with the 

application of pesticides for adult mosquito control. 

Research and Evaluation

DOHMH will conduct research to better understand where mosquito breeding occurs in 

New York City and how WN virus and other mosquito-borne viruses are maintained in 

our environment. Furthermore, DOHMH will continue to evaluate more specific bird, 

mammal and mosquito surveillance indicators that signal a threat to human health and to 

assess the efficacy of larval and adult mosquito control. 
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INTRODUCTION

 

In late August 1999, the New York City Department of Health and Mental Hygiene 

(DOHMH) detected an unusual cluster of encephalitis cases in northern Queens. This was 

due to West Nile (WN) virus, a mosquito-borne virus that had not been recognized in the 

Western Hemisphere prior to 1999. In 1999, the outbreak resulted in 44 hospitalized 

cases among City residents, including 4 fatalities. 

Since its introduction to New York City in 1999, West Nile virus has caused successive 

outbreaks in the United States each summer and fall, and has moved steadily westward. 

In 2003, West Nile virus caused the largest outbreak of meningoencephalitis ever 

recorded in the Western Hemisphere, with 9,862 cases reported overall, including 264 

deaths. In New York City, the virus has also persisted and has become endemic, causing 

137 neuroinvasive cases and 17 deaths. From 2000-2005, the number of neuroinvasive 

cases due to West Nile virus among New York City residents has ranged from 2 to 30

(median 15). 

In 2005, eleven New York City residents had WN neuroinvasive disease, all possibly or 

probably acquired within New York City. There were also three cases of WN fever 

detected in the City in 2005, one of which was likely acquired outside of New York City. 

There were 2,949 human cases and 116 human deaths reported in the United States in 

2005, and extensive WN activity detected on the west coast, in California and Oregon. 

Please see the CDC homepage at http://www.cdc.gov/ncidod/dvbid/westnile/index.htm 

for more information. 

Since 2003, universal screening of donated blood products has been conducted in New 

York City by the New York Blood Center, and six presumptively infected donors have 

been identified in New York City from 2003-2005. All implicated blood products were 

retrieved and removed from the blood supply.

The considerable and rapid spread of the virus throughout the country from 2002-2005 

provides ample evidence that WN virus is permanently established in New York City and 

in the United States. With this establishment of WN virus throughout the City and the 

region having a routine, year-round Integrated Mosquito Management (IMM) program 

has become a necessity. 

There are three probable mechanisms for WN virus overwintering within the City. The 

principle enzootic vector, Culex pipiens, overwinters in the adult stage; and it is believed 

that, at least, some infected mosquitoes successfully survive the winter. Alternatively, 

infected birds that remain in the area may harbor the virus throughout the winter months. 

As spring returns, the virus recrudesces within the birds and is readily passed to early 

season mosquitoes. A third mechanism is reintroduction of the virus into the area during 

the spring or early summer by infected migratory birds. Hence, a number of infected 

mosquitoes and/or birds are present within the City during the early spring months. At 

this time, the virus resumes its amplification cycle. As mosquitoes feed on birds, the 

virus is transmitted back and forth between the vector and the reservoir host populations 
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2006 Comprehensive Mosquito Surveillance and Control Plan 

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allowing an increasing number of birds and mosquitoes to become infected. If 

environmental conditions are optimum for transmission, the virus amplifies to a 

theoretical point of “spill over”. At this point in the amplification cycle, the virus bridges 

out of the enzootic, bird-mosquito cycle via bridge vectors. Bridge vectors are mosquito 

species that readily feed on humans and other mammals. It is at this point in the season, 

that transmission to humans occurs and when management actions are most critical. 

An effective surveillance and control program should be able to detect virus during the 

amplification cycle prior to bridge vector involvement allowing for targeted, effective 

control of the mosquito population that are limited in scope. With WN virus, the 

American crow, Corvus brachyrhynchos, is the most sensitive indicator of viral activity. 

Typically, infected crows can be found a month or more prior to human transmission. As 

the viral amplification continues, infected mosquitoes are usually found several weeks 

before human transmission. Eventually, proper surveillance will detect viral presence in 

the bridge vectors and finally in humans and other mammalian hosts. The goal of 

DOHMH’s vector surveillance program is to detect the virus in local bird and mosquito 

populations before sufficient amplification of the virus can occur, so that management 

practices can be implemented thereby reducing the number of infected mosquitoes and 

simultaneously reducing the risk of human transmission. 

DOHMH extends its gratitude to the following collaborators with whom it has worked 

closely to develop a plan that meets the specific needs of New York City: the Federal 

Centers for Disease Control and Prevention (CDC); the New York State Departments of 

Health (NYSDOH), Environmental Conservation (NYSDEC) and Agriculture and 

Markets; and New York City agencies, including the Mayor’s Offices of Operations, 

New York City Office of Emergency Management and the Departments of 

Environmental Protection, Parks and Recreation, Sanitation, Police, Citywide 

Administrative Services, Information Technology and Telecommunications and the 

Housing Authority; along with other partners. 

 
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PUBLIC EDUCATION & COMMUNITY OUTREACH

Objective

To increase public awareness of mosquito-borne diseases and surveillance, 

prevention and control techniques and activities. 

Background 

In 2000, DOHMH launched a public education campaign to increase awareness of WN 

virus. This campaign highlighted the need for New Yorkers to take personal protective 

measures against mosquito bites and to eliminate mosquito breeding sites around their 

homes. With the theme Mosquito-Proof NYC, a poster campaign in English and 

protective measures against mosquito bites and to eliminate mosquito-breeding sites 

Spanish appeared from May to October in New York City’s mass transit system. Similar 

messages were also aired on television and radio. DOHMH developed 22 fact sheets and 

made information available in 12 languages to community boards, elected officials, 

schools, community-based organizations, and the general public. In subsequent years, 

DOHMH staff has made hundreds of presentations to various community gatherings. 

DOHMH promotes WN virus prevention strategies and community participation through 

a number of venues. In 2005, the Office of Community Relations conducted targeted, 

grassroots educational outreach to senior citizens. Approximately 10,932 cans of DEET 

was successfully distributed to seniors this year, along with public education materials. 

Educators conducted 233 presentations (38 in Spanish, 12 in Chinese and 5 in Russian) to 

senior citizens throughout the City. The Health Media and Marketing Office updated the 

multi-faceted informational materials for print and radio to promote personal protective 

measures, dead bird reporting and elimination of standing water. The Press Office made 

spray notifications and personal precaution announcements through the media. Materials 

were made widely available in hard copy and electronic form (through email and the 

Agency's website), in multiple languages. Information was also made available through 

311 - the City’s non-emergency information line. 

In 2006, DOHMH will take standing water and dead bird reports via the New York City’s 

Citizen Service Center (311) and DOHMH’s enhanced Web site (nyc.gov/health). 

Callers can receive comprehensive information about WN virus, including updated 

information about adulticiding schedules by dialing 311. The Citizen Service Center 

provides callers with a live operator 24 hours a day, 7 days a week. DOHMH also 

provides information on WN virus through its web site (nyc.gov/health/wnv) in the form 

of fact sheets, press releases, adulticiding schedules, and maps. This information is 

regularly faxed to City agencies, elected officials, community boards, the Department of 

Education, hospital, nursing homes, and associations of green grocers, day camps, and 

community organizations. DOHMH will work with the Department for the Aging 

(DFTA) for distribution of West Nile virus literature and insect repellents to the senior 

citizens at social gatherings and formal meetings. 
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Adulticiding information is made available through DOHMH’s web site and 311, regular 

news broadcasts, scheduled advertising times on local radio, print media, and web sites of 

news organizations. 

Planned Activities 

The following key messages will be communicated:

• The public will be informed about the City’s comprehensive preventive strategies 

and activities (community education, surveillance, source reduction, larviciding, 

etc.) to address the threat of WN virus and to minimize the necessity of pesticide 

application for adult mosquito control. 

• The public will be asked to help eliminate mosquito-breeding sites and to report 

standing water using the Citizen Service Center (311) and via DOHMH’s 

enhanced Web site (nyc.gov/health). The public will be advised to eliminate 

standing water sites (tires, buckets, and other water-holding objects) where 

mosquitoes can breed from their property. They will also be urged to change the 

water in bird baths once each week; to clean and chlorinate swimming pools or 

drain and cover if not in use; to prevent water from accumulating in pool covers; 

and to unclog gutters and down spouts. 

• The Office of Communications will increase public awareness about the nature of 

mosquito-borne diseases and the signs and symptoms of WN virus infections 

(headache, high fever, muscle pain, weakness and disorientation). 

• The public will be informed about the proper personal protective measures to 

avoid mosquito bites such as ensuring that screens fit tightly on doors and 

windows, wearing protective clothing (long pants, long-sleeved shirts, and socks) 

and appropriate use of insect repellents. 

• The public will be informed about the importance of reporting dead birds to 

DOHMH for surveillance purposes, although it will also be made clear that the 

City does not pick up all dead birds that are reported. Information about the 

species being prioritized for testing, how to properly dispose of birds not being 

retrieved by the City, and the role that birds (especially crows) have in the 

transmission cycle of WN virus will be disseminated. 

If the application of pesticides to control adult mosquitoes becomes necessary, the 

public will be informed in a timely manner to reduce direct exposure to pesticides. 

The public will also be given detailed information about the pesticides being used and 

the potential risks associated with exposure. The public will be encouraged to contact 

the Poison Control Hotline (212-POISONS/764-7667 or 1-800-222-1222) with any 

suspected pesticide-related illness or exposure. 

 

• Fact sheets in several languages will be distributed to community-based 

organizations, community boards, elected officials, schools, elder care facilities, 

libraries, outdoor activity sites, and many other organizations City-wide. 
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• The Citizen Service Center (311) will be updated regularly with information 

pertaining to DOHMH pesticide spraying activities. Beginning in April, operators 

will be available 24 hours a day, 7 days a week for WN virus related inquiries and 

reports. 

• DOHMH’s web site (nyc.gov/health) will be regularly updated and, beginning in 

April, the public can use web-based forms for reporting dead birds and standing 

water. 

• Regular updates will be made to elected officials and community boards, who are 

essential to the City’s communication activities about WN virus activity. 

Presentations, available in multiple languages, will be offered by DOHMH staff 

to community boards and a wide variety of organizations. These will include 

information about mosquito breeding site reduction and related DOHMH 

activities. 

• Press releases regarding all activities will be issued regularly and DOHMH will 

work closely with media to achieve accuracy of the WN virus coverage. 

• In the event adulticiding is necessary: 

o Information will be released at least 24 hours in advance through the 

media, DOHMH web site and Citizen Service Center (311), and to 

hospital emergency departments, pertinent City agencies, elected officials, 

community boards, the Department of Education, nursing homes, 

associations of green grocers, day camps, and community organizations. 

Under certain conditions and with the approval of the NYSDOH, 

applications in green areas may take place with less than the required 24 

hour notice. For these cases, the green area will be closed to the public 

during and a few hours after the application of adulticide. 

o Police Department escorts will accompany the applicator’s trucks to 

announce that adulticiding is about to take place, and will urge people to 

go indoors to reduce exposure to pesticides. 
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HOST SURVEILLANCE

Objective

Utilize data on bird and mammal mortality associated with West Nile virus as a 

means of early detection of West Nile virus activity in the City in order to predict 

the spread of the disease before the onset of human illness. 

Background

Many species of birds have tested positive for WN virus, however crows and blue jays 

continue to be the birds most susceptible to the disease. Consequently, these species are 

most closely monitored by DOHMH and State agencies. However, their local populations 

have significantly declined as a result of WN virus epizootics in the last six years. In 

2005, only four percent of all dead birds reported to DOHMH were crows. Other 

potential WN virus reservoir host birds in New York City are grackles, house sparrows, 

and American robins. Of the 425 dead birds submitted by DOHMH and other 

organizations to NYSDEC, NYSDOH and the Wildlife Conservation Society for testing, 

41 (9.6%) birds tested positive in 2005. WN virus infection was highest among corvid 

species, 40% in crows and 12% in blue jays. 

OVSC will continue tracking dead birds, as this type of surveillance has shown promise 

for predicting the spread of WN virus. Also, it is the single best surveillance mechanism 

for detecting on-going transmission in a wide-region, not just where sentinel chickens are 

placed, or where mosquitoes are collected and tested. Certain species of mosquitoes feed 

primarily on birds, cycling the virus between the two populations. Testing birds for WN 

virus is, therefore, particularly important for monitoring and subsequent control of 

mosquito-borne diseases. 

There will be no sentinel live bird surveillance conducted by DOHMH in 2006 as it has 

limited use as an early warning system for human disease. Mammals do not appear to be 

as sensitive to WN virus as birds; therefore, reports of dead animals will not be solicited 

by the DOHMH in 2006. In 2001, 2002 and 2005 no mammals tested positive for WN 

virus in New York City. In 2003, one non-equine mammal and in 2004, one horse and 

one non-equine mammal tested positive for WN virus in New York City though it has not 

been concluded whether WN virus was responsible for the animal’s death. DOHMH’s 

animal surveillance efforts have been assisted by a number of partner organizations, 

including the New York City Department of Parks and Recreation, the New York State 

Department of Agriculture and Markets, the Animal Medical Center, the Staten Island 

Zoo, and the Wildlife Conservation Society. In the future DOHMH will continue to ask 

veterinarians and other animal specialists to monitor for unusual illness and death among 

mammals. 

Planned Activities

• Beginning in April, DOHMH will ask the public to report via the Citizen Service 
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Center (311) and the DOHMH web site (nyc.gov/health) the number, location, 

and types of dead birds they find. This information will be collected 24 hours a 

day, 7 days a week. Only a select group of dead birds reported to DOHMH will 

be collected and tested for WN virus. 

• DOHMH will use WN virus positive bird reports as early indicators of WN virus 

activity. Particular emphasis will be placed on the number of infected birds. 

• Beginning in April, birds reported as and confirmed to be crows, blue jays, and 

sparrows will be picked up and tested for WN virus. Following June 1, 2005 birds 

(with the exception of pigeons) that have recently expired will be retrieved when 

DOHMH is able to confirm the location of the bird with the reporting party and 

can gain access for pick-up. For those birds not retrieved by the City, the public 

will be advised to discard them safely. Although all birds may not be picked up, 

the reported dead bird information will be used by the Department to enhance its 

disease surveillance program. 

• An appropriate sample of dead birds, especially crows, blue jays, sparrows and 

robins that have died within the previous 24 hours, will be submitted for testing. 

The NYSDEC’s Wildlife Pathology Unit (WPU) will perform autopsies on all 

submitted birds and the NYSDOH’s laboratory will conduct testing for WN virus. 

• In May, DOHMH will ask local veterinarians to enhance surveillance for 

encephalitis and other mosquito-borne diseases in vertebrates by identifying 

unusual neurological abnormalities in patients, especially in mammals such as 

horses, dogs, and cats, and to report suspected infections to DOHMH. 
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HUMAN SURVEILLANCE AND PROVIDER EDUCATION

Objective

To quickly detect human illness due to mosquito-borne diseases, especially WN 

virus. 

Background

During 1999-2005, 137 New York City residents were hospitalized with neuroinvasive 

disease due to West Nile virus. Among these cases, 17 died as a result of West Nile 

infection. The epicenter in 1999 was northern Queens and in 2000 was Staten Island; 

from 2001-2005 there has been no clear epicenter, though most cases have continued to 

occur in Queens, Bronx, and Brooklyn. Most of the hospitalized cases have occurred in 

older New Yorkers (median: 69 years; range 1-93). 

In 2005, 11 New York City residents had WN neuroinvasive disease. There were also 

three cases of WN fever detected in the City in 2005. Among the 14 NYC cases of WN 

viral disease, 13 individuals possibly or probably became infected locally. 

Among these 13 individuals were 2 cases identified through the investigation of 

transplant-associated WN virus infection. A liver recipient (along with a lung recipient 

hospitalized in Pennsylvania) was ultimately diagnosed with WN neuroinvasive disease. 

The common organ donor, a Bronx resident, was found to have had symptoms 

compatible with WN fever shortly before his death, tested positive for WN virus antibody 

on serum, and was determined to have been infected most probably via a mosquito bite. 

The investigation was summarized in an MMWR Dispatch 

(http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5440a5.htm). 

The table below summarizes morbidity and mortality due to West Nile virus in New York 

City from 1999-2005: 

1999 2000 2001 2002 2003 2004 2005

Cases 46 14 9 30 31 5 14

Syndrome

 Neuroinvasive 44 14 7 29 30 2 11

 WN Fever 2 2 1 1 3 3

71 62 51 73 66 34 61

(5-95) (36-87) (44-75) (22-91) (8-93) (1-66) (27-84)

# Deaths 4103702

Median age (yrs) 80 87 0 75 72 0 61

Case fatality rate 9% 7% 0 10% 23% 0 18%

Median age* 

(yrs) (Range)

* Median age calculated for neuroinvasive cases only 

Serosurveys performed in Queens (1999) and Staten Island (2000) indicated that 
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2006 Comprehensive Mosquito Surveillance and Control Plan 

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approximately 140 subclinical WN virus infections, including 30 cases of WN fever, 

probably occurred for every one hospitalized case. Therefore, an estimated 15,070 

asymptomatic infections and 4,110 cases of WN fever have occurred among New York 

City residents from 1999-2005. The vast majority of asymptomatic infections and WN 

fever cases go undetected and unreported in New York City, since many individuals with 

febrile illness may not seek medical attention and may not be tested for WN virus even if 

they do see a provider. Commercial testing is now available for WN virus, but many 

New York City providers still rely upon free testing for WN virus at the Public Health 

Laboratory. 

As part of an active surveillance and provider education program, DOHMH’s Bureau of 

Communicable Disease offers slide presentations to health care providers. Broadcast 

alerts are issued by e-mail and facsimile to all NYC hospitals, encouraging prompt 

reporting of suspected cases of encephalitis, aseptic meningitis and acute flaccid paralysis 

from July through October. Providers and laboratory personnel are also instructed on 

how to submit specimens for WN virus testing to the DOHMH Public Health Laboratory 

through these same outreach methods. The Bureau of Communicable Disease maintains 

a database for all suspected cases of WN virus, and in past years has actively arranged for 

the timely collection and transportation of appropriate diagnostic specimens to the 

DOHMH Public Health Laboratory. 

In prior years, DOHMH actively facilitated the transportation of specimens to the 

DOHMH Public Health Laboratory for rapid WN virus testing for all cases meeting 

certain criteria. Beginning this year, providers will be encouraged to continue WN 

testing for appropriate patients through commercial laboratories, or to arrange for 

shipment of specimens to the DOHMH Public Health Laboratory themselves. Under 

special circumstances specimen transportation and testing will be by DOHMH (e.g. high 

suspicion for WN virus, possible transfusion or transplantation related cases, or unusual 

clustering of cases suggestive of an outbreak of WN virus or another cause of 

encephalitis). 

Serologic testing for WN virus is performed at the DOHMH Public Health Laboratory 

(PHL). The laboratory performs tests for antibodies to WN. If physicians request 

antibody testing dengue, Eastern equine encephalitis and/or St. Louis encephalitis (SLE) 

viruses, specimens will be referred to the NYSDOH Wadsworth Laboratory for testing. 

Serologic specimens which test positive for WN virus at PHL are sent for confirmation 

by plaque reduction neutralization testing to the NYSDOH if appropriate. Cerebrospinal 

fluid specimens from hospitalized patients with encephalitis are also forwarded to the 

NYSDOH for testing by polymerase chain reaction for a panel of viruses that cause 

human encephalitis.

Planned Activities

• Beginning in late June, DOHMH will remind providers to report all suspected 

cases of WN virus neuroinvasive disease (encephalitis, aseptic meningitis or acute 

flaccid paralysis), and to test all hospitalized patients, either at commercial 

laboratories or at the PHL, for WN virus. 
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• From July through October, regular broadcast updates will be sent to all City 

hospitals and infectious disease specialists regarding the importance of reporting 

suspected West Nile virus cases. DOHMH will provide the criteria for reporting 

and submission of appropriate laboratory specimens for WN virus testing. To 

maintain physician awareness throughout the mosquito season, these alerts will be 

sent at least monthly with updated information on WN virus activity. 

• DOHMH will encourage providers to test appropriate suspect cases through 

commercial laboratories. However, the DOHMH Public Health Laboratory will 

continue to conduct diagnostic testing for WN virus and forward specimens for 

testing for other mosquito-borne viral causes of encephalitis to NYSDOH, as 

needed. 

• DOHMH will work closely with NYSDOH and CDC to ensure that surveillance 

information is standardized and remains confidential. 

• DOHMH will conduct health care provider education to increase knowledge 

about the proper detection, prevention and clinical management of mosquitoborne diseases and other types of encephalitis and meningitis. Presentations 

will be made at local hospitals and to specialty societies as requested. Also, 

DOHMH will provide educational opportunities on mosquito-borne diseases 

through its Continuing Medical Education and Continuing Nursing Education 

programs. 

• The Bureau of Communicable Disease will work with other agencies to ensure 

that any case of West Nile infection in a person who has received or donated 

blood products or organs is rapidly investigated and reported so that other affected 

blood products or organs can be promptly identified and withdrawn before they 

are used. 

The Bureau of Communicable Disease will work to educate pregnant women, and 

obstetricians and gynecologists in New York City about the possible impact of WN 

infection on the fetus and the need to test pregnant women who develop illnesses 

consistent with WN fever or neuroinvasive disease, to encourage pregnant women with 

evidence of WN viral infection to participate in the CDC WN and pregnancy registry. 

The Bureau will collaborate with CDC and the treating obstetricians and pediatricians to 

closely monitor any potentially affected fetus or neonate and to perform comprehensive 

diagnostic testing for WN virus infection or possibly associated adverse effects. 
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MOSQUITO SURVEILLANCE 

Objective

To monitor the seasonality, population dynamics and abundance of mosquito 

populations and detect the presence of arboviruses 

Background

Mosquitoes were collected weekly from mosquito traps over 72 permanent locations 

throughout New York City in 2005. A total of 143,258 adult mosquitoes were identified 

to species, of which 92,262 belonging to twenty-two species were tested for the presence 

of West Nile virus infection. Three mosquito species, Culex pipiens, Cx. restuans, and 

Cx. salinarius were infected with WN virus. Of the 4,860 mosquito pools tested, 122 

tested positive for WN virus: 38 in the Bronx; 6 in Brooklyn; 22 in Staten Island; and 56 

in Queens. Cx. pipiens was identified as the primary enzootic vector of WN virus from 

1999-2005 based upon the number of positive pools. In fall and winter 2006, hibernating 

Culex females were collected from indoor resting sites and were kept at 24-25 o

C with 

14:10 (L:D) photoperiod for 20-30 days and later tested for the presence of WN virus. 

No WN virus was detected in these overwintering mosquitoes.

The risk of mosquito-borne disease depends on both the number of mosquitoes capable of 

transmitting the virus and the prevalence of the virus among these mosquitoes. Proper 

surveillance data on larval and adult mosquitoes is important for guiding appropriate 

prevention and control activities. Larval surveillance can provide information on 

expected adult mosquito density and can indicate areas where efforts to eliminate 

mosquitoes at their source (breeding sites) should be targeted. Adult mosquito 

surveillance and viral testing provide early predictive information about the potential for 

a disease outbreak. 

Planned Activities

 

• DOHMH will continue to work closely with other City agencies to collect and 

map information on potential mosquito-breeding habitats. 

• DOHMH will determine which areas should be regularly inspected for the 

presence of larvae. These sites will be subjected to routine inspection to determine 

the presence of mosquito larvae. 

• Larval habitat information will be collected and updated throughout the season. 

• In the urban areas, mosquito trapping will be conducted from sewer and adjacent 

buildings by using light traps in response to resident complaints. 

• From June to October, DOHMH will trap adult mosquitoes at more than 50 

permanent sites throughout the 5 boroughs. The trapping season may be 
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lengthened or shortened depending on the weather. 

• Mosquitoes will be collected using DOHMH miniature light and gravid traps on a 

weekly basis. Each trap collection will be sorted by species of mosquitoes 

collected. Information on the location, collection data, trap type and the total 

number of female mosquitoes will be recorded. 

• Extra trapping will be conducted to collect day biting mosquitoes using omni 

directional Fay Prince traps and mosquito magnets. 

• Adult mosquito trapping will be expanded in areas where WN virus is detected in 

mosquitoes, birds, other animals, and humans. This will help determine extent of 

viral activity and delineate spray zones. 

• In the event that pesticides are applied for adult mosquito control, DOHMH will 

set traps more frequently to evaluate the efficacy of the control measures. 

• The DEP will continue to use mosquito magnet traps to survey and control adult 

mosquitoes at wastewater treatment plants. Additionally, DOHMH will place 

mosquito magnet traps to survey and control adult mosquitoes in the Rockaways 

Peninsula. 
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LARVAL MOSQUITO CONTROL 

Objective 

To reduce the abundance of adult mosquitoes through the use of Integrated 

Mosquito Management (IMM) practices 

Background

Culex pipiens, a primary vector of WN virus and one of the most common mosquitoes 

found in urban areas, breed quickly and use standing or slow-moving water containing 

decaying organic materials to lay their eggs. Prime breeding sites include discarded tires 

left outdoors, poorly maintained bird baths, clogged rain gutters, unused swimming and 

plastic wading pools, pots and pans with standing water, and puddles that last for a week 

or more. Eliminating breeding sites is the simplest and most effective way to reduce the 

number of mosquitoes. Every residential and commercial property owner should 

regularly inspect their property and buildings to determine if conditions are conducive to 

mosquito breeding and endeavor to eliminate those conditions. Mosquito breeding can be 

prevented by either eliminating the standing water (source reduction), or if that is not 

possible, treating the water with larvicide to prevent mosquitoes from developing. 

DOHMH’s public education campaign emphasizes the need for New Yorkers to 

eliminate mosquito-breeding sites around their homes. From April to October 2005, 

DOHMH received 3,811 complaints of standing water through the City's Citizen Service 

Center Information Line (311), on DOHMH’s web site, and from elected officials and 

community groups. The NYC DOHMH investigated each of the complaints. Every 

report led to a letter being sent to the property owner regarding the need to eliminate 

mosquito-breeding sites and 3,449 sites were visited and checked for the presence of 

mosquito breeding. In order to respond to egregious conditions, the Board of Health 

adopted a resolution that made standing water a public health nuisance and allowed for 

the issuance of Notice of Violations to unresponsive property owners. In 2005, 813 

Notice of Violations were issued to unresponsive landlords. 

DOHMH will conduct extensive larviciding in accordance with permits issued by NYS 

Department of Environmental Conservation (DEC) in catch basins (street corner storm 

drains), sewage treatment plants, and areas of permanent standing water. DOHMH works 

with the New York City Department of Environmental Protection (DEP), the New York 

City Housing Authority, and the New York City Department of Parks and Recreation to 

treat catch basins and other potential breeding sites for mosquitoes, and has expanded the 

use of mosquito larvae-eating fish at DEP wastewater treatment plants. Approximately 

140,000 catch basins across the City will be inspected and/or treated at least twice each 

season by hand application of larvicides. In areas that are inaccessible by ground 

vehicles, larvicide may be applied aerially. 

The larvicides most commonly used in New York City are VectoLex (Bacillus 

sphaericus),VectoBac [Bacillus thuringiensis var. israelensis (Bti)] and/or Altosid 
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(methoprene). B. sphaericus and Bti are naturally occurring soil bacteria that produce 

toxins which cause disease in mosquito larvae. These products are considered ideal for 

mosquito management because of their specificity to mosquitoes and because of their 

lack of toxicity to humans and the natural enemies of mosquito larvae. These bacteria 

form asexual reproductive cells, called spores, which enable them to survive in adverse 

conditions. They also produce unique crystalline bodies. When eaten, the crystalline 

bodies dissolve in the intestine of the larvae and paralyze the cells in the gut, interfering 

with normal digestion and triggering the larvae to stop feeding. The spores can then 

invade other tissues, multiplying in the larva’s blood, until the insect dies. Death 

typically occurs within a few hours of ingestion. 

Planned Activities

• Under the direction of the Mayor’s Office of Operations WN virus Task Force, 

OVSC and other City agencies have identified areas of standing water associated 

with surface grading problems, road construction, clogged sewers and catch 

basins, obstructed waterways, etc. that are serving as mosquito-breeding habitat. 

These conditions will be remediated as they are identified. 

• The WN virus Task Force will work to inform large-property owners and 

managers of the need to eliminate mosquito-breeding sites on their property or to 

properly treat them with larvicides. 

• DOHMH will work with the New York City Department of Sanitation to 

prioritize and enhance the enforcement of lot cleaning and to ensure an aggressive 

tire disposal program. Abandoned lots are particularly conducive to mosquito 

breeding, and in areas where WN virus has already been detected these lots will 

be targeted for remediation. 

• DOHMH will work with the New York City Department of Buildings to develop 

and implement a protocol for requiring all City’s demolition and excavation 

contractors to larvicide when their activities result in significant sources of 

mosquito breeding. 

• The public will be asked to help eliminate mosquito-breeding sites and to report 

standing water using the City's toll-free Citizen Service Center Line (311) and the 

DOHMH Web site (nyc.gov/health). 

• OVSC will monitor reported breeding sites; send letters to property owners asking 

them to address the problem; conduct on-site inspections of the more egregious 

conditions; make referrals to appropriate agencies for abatement; and, if 

necessary, issue notices of violation. 

• DOHMH will again use VectoLex (Bacillus sphaericus), VectoBac/AquaBac 

(Bacillus thuringiensis var. israelensis, Bti) and/or Altosid (methoprene) to 

control mosquito larvae. DOHMH will continue to explore other DEC-approved 

products that may increase the effectiveness of the larviciding program. 
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• Beginning in May, larvicides will be applied at wastewater treatment plants, 

parks, and other surface waters, if larval breeding is determined to exist. 

Applications will be made by hand, backpack or aerially via helicopter and 

continue to be applied as needed throughout the mosquito-breeding season. 

• Beginning in June, larvicides will be applied to sewers and to more than 140,000 

catch basins citywide. Applications will continue, based upon larval surveillance 

findings, as needed throughout the mosquito-breeding season. 

• With the identification of an infected bird or mosquitoes in the area, OVSC staff 

will intensify larval control. Targeted neighborhoods will have expanded public 

outreach regarding breeding site elimination and personal protection; also 

community-specific media materials will be distributed. 

• DOHMH will work with the Parks Department and other partners to ensure that 

green areas (e. g., parks, cemeteries, and golf courses) receive intensified 

mosquito prevention activity, especially in areas where infected dead birds or 

mosquitoes are found. 

• The DEP will continue to use larvae-eating fish at wastewater treatment plants. 

• During inspections, DOHMH will provide “Mosquito Dunks” to property owners 

with clear written instructions on how to use the larvicide product. 

• DOHMH will provide occupational safety and health training to all employees 

involved in mosquito surveillance and control operations. Additionally, DOHMH 

will require that all employees from contracted vendors be provided with similar 

training as well as appropriate personal protective equipment. 

• For residents conserving rainwater, OVSC will recommend covering the barrels 

or other water holding containers with a tight-fitting lid or very fine mesh screen. 

Also, bacterial larvicides containing Bti can safely be placed in the barrels to 

control any mosquito larvae that may be developing. 
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ADULT MOSQUITO CONTROL 

Objective

To reduce the abundance of WN virus infected adult mosquitoes in targeted areas 

through the judicious use of pesticides 

Background

Comprehensive vector, bird and human surveillance data collected during the last five 

seasons have allowed DOHMH to develop more sensitive surveillance criteria for 

determining the level of WN virus activity in birds and mosquitoes that indicate 

a significant risk for a human disease. DOHMH will monitor this surveillance data on a 

citywide basis to identify areas at risk for human transmission. 

The adulticides used during the last six seasons in New York City is Sumithrin. This 

product is a first-generation synthetic pyrethroid that has been used for more than 30 

years. Sumithrin, similar to other pyrethroids, provides a rapid knockdown of adult 

mosquitoes. It exhibits very low mammalian toxicity, degrades very rapidly in sunlight, 

provides little or no residual activity, and does not bio-accumulates in the environment. 

This product is applied at very small quantities per acre and is therefore referred to as 

ultra low volume (ULV) application. ULV-delivery techniques minimize environmental 

impacts while effectively managing adult mosquito populations. In addition, DOHMH 

adulticiding operations are monitored by city, state and federal officials to ensure 

compliance with all USEPA and NYSDEC requirements. 

The presence of mosquito-borne viral pathogens in or near New York City will result in 

one or more responses or interventions by DOHMH. These interventions can range from 

routine continuing existing surveillance to, in worst-case scenarios, large-scale aerial 

application of adulticides. DOHMH will utilize its surveillance data to assess the risk of 

an outbreak of human disease and the need to apply pesticides in a limited and targeted 

area to control adult mosquitoes by considering habitat; time of year; weather conditions; 

the intensity of viral activity; the distribution, density, species, age and infection rate of 

the vector population; and the density and proximity of human populations. The response 

of DOHMH will depend upon, but not be limited to: the intensity and persistence of 

pathogen activity, proximity of pathogen activity to human populations within the City, 

time of year, mosquito population density, and weather conditions. Because these 

conditions can vary greatly and cannot be predicted, a consultation process will be used 

to determine which, if any, responses are appropriate, on a case-by-case basis. The 

responses initiated by the DOHMH can be grouped into 3 broad categories or levels of 

risk. 

Planned Activities

Level 1 – No Pathogen Detection

DOHMH Responses: Surveillance and Control programs continue as outlined in the 
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2006 Comprehensive Mosquito Surveillance and Control Plan 

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City’s Mosquito Surveillance and Control Plan. Periodic reports or communications are 

made to the WN virus Steering Committee providing current status of the various 

surveillance programs. Periodic press releases are issued providing the public with 

current surveillance results. 

Level 2 – Initial or Single Pathogen Detection

Initial or a single detection of mosquito-borne viral pathogens in mosquito populations or 

avian populations in or near New York City will result in a move to Level 2 responses. 

DOHMH Responses: OVSC recommendations will be communicated to the WN virus 

Steering Committee and the DOHMH Commissioner. Upon approval by the 

Commissioner, a press release will be drafted, notifying the public of the recent findings. 

Surveillance programs will continue with the following added activities: 

• CDC Light Traps will be added to the area of concern if additional surveillance 

data are required. 

• Larval surveillance and enhanced adult trapping will be conducted in affected 

areas if needed. 

• Laboratory testing of mosquito pools will be given priority in bridge vector 

mosquito species (i.e. Aedes spp., Ochlerotatus spp., Cx. salinarius). 

• Data from these additional traps and surveillance measures will aid in determining 

the extent of pathogen transmission and mosquito populations and be used to 

guide control measures, if applicable. 

Level 3 – Continued or Multiple Pathogen Detections

Persistent detection of mosquito-borne pathogens or detection in bridge vector 

mosquitoes or in non-avian vertebrate populations in or near New York City will result in 

a move to Level 3 responses. 

DOHMH Responses: OVSC recommendations will be communicated to the WN virus 

Steering Committee and the DOHMH Commissioner. Upon approval by the 

Commissioner, a press release will be drafted, notifying the public of the recent findings. 

Surveillance programs will continue as noted above. Control measures will be 

implemented. 

• CDC Light Traps will be added to the area of concern if additional surveillance 

data are required. 

• Larval surveillance and enhanced adult trapping will be conducted in affected 

areas if needed. 

• Laboratory testing of mosquito pools will be increased in bridge vector mosquito 

species (i. e. Aedes spp., Ochlerotatus spp., Cx. salinarius). 

• Control measures to be considered: 
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o Application of larvicides (including aerial applications) to areas breeding 

large numbers of mosquitoes 

o Ground application of adulticides to immediate areas of concern 

o Aerial application of adulticides to broader areas, based upon surveillance 

data 

o Recommend the restriction and/or cancellation of outdoor evening 

activities 

o Recommend the closing of recreational areas 

• Monitor the efficacy of the adulticiding activities. 

• DOHMH will comply with Local Law 37 of 2005, which sets forth requirements 

on pesticide use by New York City. 

• DOHMH will consider EPA and NYSDEC registered products for mosquito 

control that contain the following active ingredients: sumithrin, resmethrin, 

permethrin, dibrom, or naled. The City will continually review of the available 

information on the health impact of pesticides. Any products used will be applied 

in compliance with City, State, and Federal laws and regulations. 

• The public will be notified of adulticide schedules in advance, which will allow 

sufficient time to take any necessary precautions to reduce pesticide exposure. 

(See Public Education and Community Outreach) 

• Hospitals will be notified regarding the adulticiding schedule. Information on the 

pesticide to be used will be provided to the public, physicians and other health 

care providers. 

• For quality assurance purposes, a private contractor, independent of the pesticide 

applicator, will provide guidance and assist with the technical elements of 

pesticide application so that operations are conducted according to plan and 

pursuant to applicable regulations. 

• Adult mosquito control will be scheduled when mosquitoes are most active and 

when weather conditions are conducive to successful application. 

• Information will be released 24 hours in advance of scheduled spray event 

through the media, the DOHMH web site and West Nile virus Information Line 

and pertinent City and community organizations. 

• DOHMH will monitor and assess control activities for any potential 

environmental and health effects through several measures, including pre- and 

post-spray environmental sampling and addressing pesticide exposure complaints 

received by DOHMH. 
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• Depending on surveillance findings and other criteria, DOHMH or its Contractor 

may apply targeted adulticides in response to community concerns about nuisance 

mosquitoes on the Rockaway Peninsula. 
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SURVEILLANCE OF POTENTIAL ADVERSE HEALTH EFFECTS FROM 

PESTICIDE EXPOSURE 

Objective

To perform passive and syndromic surveillance to monitor for possible exposure to 

pesticides used to control adult mosquitoes and the potential health sequelae due to such 

exposure. 

Background

Since exposure to pesticides has the potential to cause adverse reactions, particularly 

among those with pesticide sensitivity or underlying health conditions, beginning in 

2000, DOHMH took additional care to provide advance notification whenever adulticide 

applications occurred. Prior to conducting adult mosquito control activities, information 

on pesticides was sent to all hospital emergency departments, which included product 

information on pesticides, Material Safety Data Sheets, and other information relevant to 

identifying possible exposures to pesticides. Each year since 2000, calls to the New York 

City Poison Control Center (NYC PCC) were monitored during pesticide spraying and 

relevant exposures were forwarded to the New York State Pesticide Poisoning Registry 

(NYS PPR) for review and possible inclusion in the registry. In 2001, active surveillance 

for pesticide-related health complaints was performed. In this regard, chart review was 

conducted in emergency departments and physicians were randomly surveyed in the 

affected areas by telephone to determine if any individuals had sought care for symptoms 

related to possible exposure to adulticides. No cases of individuals reporting to 

emergency departments or seeking care from their physicians for health complaints 

related to adulticide exposure were found through these activities. Additional research 

was conducted to determine whether pesticide applications associated with West Nile 

Virus mosquito control were associated with negative health outcomes. As a recent 

publication reported, no such associations were found.1

 

Beginning in 2002 syndromic surveillance was adopted as a surveillance tool to identify 

any possible respiratory symptom related cluster in areas in which a spray action 

occurred. If such a cluster is identified, DOHMH conducts further review of emergency 

department data to investigate the possible etiology of that cluster. In addition, Poison 

Control Center pesticide-related calls are monitored for number and severity that are 

geographically and temporally associated with spray events. 

Planned Activities

Prior to conducting adult mosquito control activities, information on pesticides and their 

possible adverse health effects will be sent to all hospital emergency departments, 

including product information on pesticides, Material Safety Data Sheets, and other 

information relevant to identifying possible exposure to pesticides. Calls received by the 

 

1

 Karpati AM, Perrin MC, Matte T, Leighton J, et al. Pesticide Spraying for West Nile Virus Control 

and Emergency Department Asthma Visits in New York City, 2000. Environ. Health Perspect. 

2004 Aug; 112(11): 1183-7. 
New York City Department of Health and Mental Hygiene 

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New York City Poison Control Center (NYC PCC) will continue to be monitored during 

pesticide spraying for geographic and spatial associations with spray events. These data 

will continue to be forwarded to the NYS Pesticide Poisoning Registry for possible 

follow-up and inclusion in the Registry. Syndromic surveillance will also continue to be 

utilized to identify possible asthma clusters in the zip codes in which spraying occurs. 

Statistical and field investigation methods for evaluating spatial and temporal clustering 

are described in recent publications.2 In the event that a possible respiratory symptom 

cluster is identified, emergency department chart review will be considered to investigate 

the possible etiology of that cluster at near by hospitals. 

 

2

 See for example: Heffernan, R., F. Mostashari, D. Das, et al. New York City Syndromic 

Surveillance Systems MMWR September 24, 2004 / 53(Suppl);23-27; and Steiner-Sichel, L., J. 

Greenko, R. Heffernan, M. Layton, and D. Weiss. Field Investigations of Emergency Department 

Syndromic Surveillance Signals. New York City MMWR September 24, 2004 / 53 (Suppl.);184-

189. 
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2006 Comprehensive Mosquito Surveillance and Control Plan 

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RESEARCH AND EVALUATION

Objective

To better understand the transmission and pathogenicity of mosquito-borne 

diseases and to assess the effectiveness of DOHMH surveillance, prevention and 

control methods 

Background

One of the most important roles for public health professionals is to assess the potential 

impact of a disease on a population and to devise safe and effective methods for reducing 

the risk of disease transmission. DOHMH, in collaboration with CDC and NYSDOH, has 

studied closely the risk factors for infection of and morbidity and mortality from WN 

virus. However, many questions remain about how the virus circulates in nature. 

Furthermore, some of the control methods used for managing mosquito populations, 

especially the application of pesticides for adult mosquitoes, are not without potential 

impact. However, alternative control measures lack sufficient efficacy or environmental 

impact data to allow their wholesale integration into the City’s IMM Plan. The 

environmental impact statement and other research endeavors are important tools used to 

assess potential adverse health effects associated with pesticide exposure. Additional 

research is needed in this area as well as in assessing improved techniques for larval and 

adult mosquito control in New York City. 

Planned Activities

• DOHMH will continue to work closely with Federal, State, and Local partners to 

conduct research that will identify the most effective predictors of human illness 

from WN virus in New York City, including the analysis of overwintering 

mosquito populations and the use of predictive dead bird cluster models. 

• DOHMH will continue to refine the New York City-specific phased response for 

risk categories of mosquito-borne disease outbreaks based on the ongoing 

analyses of bird, mosquito, mammalian and human surveillance data. 

• DOHMH will evaluate the most cost-effective methods of surveillance and 

control. 

• DOHMH will research and evaluate the potential public health and environmental 

impact of the application of pesticides for adult mosquito control. 

• In collaboration with CDC and NYSDOH, OVSC will publish new and relevant 

information about mosquito-borne disease transmission in New York City in peerreviewed public health and medical journals. 

• DOHMH will conduct research to determine the blood feeding preference of the 
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mosquito vectors of WN virus in NYC using molecular techniques. This 

information will help determine what animals are the primary hosts and focus 

surveillance and control activities accordingly. 

• DOHMH will research and evaluate the development of resistance in mosquitoes 

due to the application of pesticides (microbial larvicides and adulticides). 

• DOHMH will conduct an analysis to predict the risk of West Nile virus infections 

and the outcome of interventions in New York City using Probabilistic modeling 

techniques, Spatial Statistics and Geographic Information System (GIS). 

• DOHMH will test hibernating mosquitoes for WN virus infection to determine 

their role in the overwintering of WN virus from one season to the next. 

• The host seeking activity patterns of mosquitoes will be determined by using 

collection bottle rotator traps in various habitats such as marsh, urban areas and 

parks. 

• Larval surveillance will be conducted before and after the control activities in the 

catch basins (storm drain) and natural breeding sites for determining larval control 

efficacy of the pesticides. 
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APPENDIX A: 

QUESTIONS AND ANSWERS ABOUT WEST NILE VIRUS 

Q: What is West Nile virus? 

A: West Nile virus is a mosquito-borne virus that can infect humans, birds, horses, and 

other mammals. In humans, infection with the virus usually causes no symptoms at 

all or a mild, flu-like illness. However in some cases, particularly among the elderly, 

it can also cause more severe neurological diseases such as encephalitis or aseptic 

meningitis. West Nile virus initially appeared in North America in New York City in 

1999. Since then, the virus has spread across the continental United States. 

Q: How is West Nile virus spread? 

A: West Nile virus is spread predominantly to humans by the bite of an infected 

mosquito. In 2002 other methods of human transmission were discovered. It has now 

recently been shown that West Nile virus can be transmitted to humans who receive 

infected organs through transplantation, or who receive transfusions of infected blood 

or blood products. In 2003, two cases of blood transfusion-associated WN virus 

infection were documented, one in Texas and one in Nebraska. Also, in 2002 there 

was one case of transmission from a pregnant woman to her fetus and one case of 

probable mother-to-child transmission through breast-milk. West Nile virus is NOT 

spread by person-to-person contact such as touching, kissing, or caring for someone 

who is infected. 

Q: Who is most at risk for getting West Nile encephalitis after being bitten by a WN 

virus infected mosquito?

A: People older than 50 years of age have the highest risk of severe disease, such as 

encephalitis. It is unknown if immunocompromised persons are at increased risk for 

WN virus disease. 

Q: Where did the West Nile virus come from? 

A: Outbreaks of the West Nile virus have occurred before in Africa, Egypt, Israel, Asia, 

Romania, Russia and France. Prior to 1999, the West Nile virus had never been 

discovered in the Americas. The virus was most likely introduced by an infected bird 

or mosquito that was imported from a country where the virus is common. 

Q: Can you get West Nile virus directly from birds? 

A: Currently, there have been no reported cases of West Nile virus being spread directly 

from live or dead birds to the general public. However, dead birds can carry a variety 

of other diseases and should never be handled with bare hands. Use gloves to 

carefully place dead birds in double-plastic bags and then place dead birds in the 

outdoor trash. 

Q: Besides mosquitoes, can you get West Nile virus directly from other insects or 

ticks?

A: Infected mosquitoes are the primary source of West Nile virus and caused the recent 
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outbreaks in NYC. Although several types of ticks in Africa and Europe have been 

found infected with WN virus, there is no information to suggest that ticks or other 

insects in this country are able to transmit West Nile virus. 

Q: What are the symptoms of West Nile virus? 

A: Most people who are infected with West Nile virus either have no symptoms or 

experience mild illness such as fever, headache and body aches before fully 

recovering. Some may also develop a mild rash or swollen lymph glands. In some 

individuals, particularly the elderly, West Nile virus can cause serious disease that 

affects brain and spinal tissue. Severe illness may include encephalitis (inflammation 

of the brain), meningitis (inflammation of the membrane around the brain), and acute 

flaccid paralysis (a polio-like syndrome in which muscles become very weak or 

paralyzed). Symptoms may include: headache, high fever, stiff neck, confusion, 

coma, tremors, convulsions, and muscle weakness or paralysis. At its most serious 

West Nile virus can cause permanent neurological damage and death. 

Q: If a pregnant woman gets infected with West Nile virus, can it affect her fetus?

A: In 2002 there was one case of transmission of West Nile virus from mother to fetus 

during pregnancy. The newborn was infected with West Nile virus at birth and had 

severe medical problems, including abnormalities of the brain; however, it is 

unknown whether these problems are due to West Nile virus or some other cause. 

Pregnant women should take precautions to reduce their risk for West Nile virus 

infection by avoiding mosquitoes, wearing protective clothing and using insect 

repellents containing DEET. (Please see the DOHMH fact sheet on Insect Repellent 

Use & Safety for more information on DEET). When West Nile virus transmission is 

occurring in an area, pregnant women who have illness with fever should see their 

health care provider. 

Q: How is West Nile encephalitis treated? 

A: There is no specific therapy. In more severe cases, intensive supportive therapy is 

indicated, i. e. , hospitalization, intravenous (IV) fluids and nutrition, airway 

management, ventilatory support (ventilator) if needed, prevention of secondary 

infections (pneumonia, urinary tract, etc. ) and good nursing care. 

Q: Is there a vaccine against West Nile virus? 

A: No, but several companies are working towards developing a vaccine. 

Q: How long does it take to get sick if bitten by an infected mosquito? 

A: Most people who are infected with West Nile virus have no symptoms or experience 

only mild illness. If illness does occur, symptoms appear within 3 to15 days of being 

bitten by an infected mosquito. 

Q: What should I do if I think I have West Nile encephalitis? 

A: You should seek medical care as soon as possible if you develop signs of encephalitis 

such as/including: fever, muscle weakness, and confusion, 

Q: What can I do to reduce my risk of becoming infected with West Nile virus? 

A: From June through October, when mosquitoes are most active, take the following 
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precautions: 

• Wear protective clothing such as long pants and long-sleeved shirts. 

• Avoid shaded, bushy areas where mosquitoes like to rest. 

• Limit outdoor evening activity, especially at dusk and dawn when mosquitoes 

are most active. 

• Use insect repellent containing between 13-25% DEET to minimize the risk 

of being bitten by a mosquito. Formulations containing more than 25% DEET 

are unnecessary and may enhance skin reactions on some people. Extra 

precaution should be used when applying repellents to children and infants. 

As with all products, the user should follow the manufacturer’s usage 

recommendations. 

Q: What can I do around my home to help reduce exposure to mosquitoes? 

A: Mosquitoes lay their eggs in standing or slow moving water. Also weeds, tall grass, 

and bushes provide an outdoor resting place for mosquitoes. Mosquitoes breeding or 

resting on your property can then enter homes through unscreened windows or doors, 

or broken screens. 

• Repair or replace all screens in your home that have tears or holes. 

• Eliminate any standing water that collects on your property. 

o Remove all discarded tires from your property. 

o Dispose of tin cans, plastic containers, ceramic pots, or similar 

water-holding containers. 

o Make sure roof gutters drain properly. Clean clogged gutters in the 

spring and fall. 

o Clean and chlorinate swimming pools, outdoor saunas and hot tubs. If 

not in use, keep empty and covered. 

o Drain water from pool covers. 

o Change the water in bird baths once a week. 

o Turn over plastic wading pools and wheelbarrows when not in use. 

• Remind or help neighbors to eliminate breeding sites on their properties. 

Q: What is the City doing to address the possible return of West Nile virus? 

A: DOHMH, along with other City, State and Federal agencies, has developed a 

comprehensive plan to reduce the risk of illness due to West Nile virus. The main 

goal of this plan is to decrease the number of adult mosquitoes by eliminating their 

breeding sites wherever possible, and applying larvicides (to kill the immature larval 

form of the mosquito) to areas with stagnant water that cannot be drained completely. 

The City also will regularly test mosquitoes and birds for West Nile virus throughout 

the spring and summer. If West Nile virus is found at levels that indicate a threat to 

human health, local applications of pesticides may be undertaken to prevent people 

from becoming infected. 

Q: Is the City planning to apply pesticides as was done previously? 

A: If West Nile virus is detected in the community, the City’s initial response will be to 

intensify its efforts to reduce mosquito-breeding sites and increase its levels of 

larviciding in those areas in which WN virus has been found. Reducing the adult 

mosquito population with pesticides (adulticides) approved by the US Environmental 

Protection Agency (EPA) will be done if necessary to prevent human illness. The 
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2006 Comprehensive Mosquito Surveillance and Control Plan 

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decision to spray, either on the ground or by air, will be based on surveillance 

information and the documentation of West Nile virus activity at a level that indicates 

a threat to human health. Adulticiding will be concentrated in areas most at risk for 

disease occurrence. 

Q: What health risks are posed to people and pets from pesticides for adult mosquitoes? 

A: In the amounts used, risks to people and pets are relatively low. However, some 

people may be more sensitive to such pesticides and may want to reduce their chance 

of exposure by following the suggestions below. Anyone experiencing persistent or 

significant adverse reactions to pesticides should seek medical care or call the NYC 

Poison Control Center at (212) POISONS or (212) 764-7667. 

Q. Will the public be notified in advance about spraying activities? 

A: Residents can learn about adulticiding schedules in advance through public service 

announcements, the media, the City's website (nyc.gov/health), and a telephone 

information line (1-877-WNV-4NYC). 

Q: If the City sprays pesticides for adult mosquitoes, what can I do during 

spraying to reduce the risk of exposure to pesticides? 

A: If spraying becomes necessary, the NYC DOHMH recommends that all individuals 

take the following precautions to avoid direct exposure to pesticides and reduce the 

reactions: 

o Some individuals are sensitive to pesticides. Persons with asthma or other 

respiratory conditions are especially encouraged to stay inside during spraying 

since there is a possibility that spraying could worsen these conditions 

o Air conditioners may remain on. But if you wish to reduce the possibility of 

exposure to pesticides, set the air conditioner vent to the closed position, or 

choose the recirculate function 

o If you wish to minimize your exposure to pesticides, you may want to bring 

children's toys, outdoor equipment and clothes from outdoor areas inside 

during spraying. 

o If outdoor equipment and toys are exposed to pesticides, they may be washed 

with soap and water to reduce the possibility of exposure 

o Wash skin and clothing exposed to pesticides with soap and water. 

Anyone experiencing adverse reactions to pesticides should seek medical care or call 

the NYC Poison Control Center at (212) POISONS or (212) 764-7667. 

Q: If I live in an area where birds or mosquitoes with West Nile virus have been 

reported, and a mosquito bites me, am I likely to get sick? 

A: No. Evidence indicates that the chance of human infection and illness resulting from 

West Nile virus is quite low. In addition, the greatest risk is to those over age 50, 

particularly the elderly. These members of the population should take the greatest 
New York City Department of Health and Mental Hygiene 

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care to prevent exposure to mosquito bites. 

Q. I've gotten a mosquito bite. Should I be tested for West Nile virus? 

A: No. Illnesses related to mosquito bites are still uncommon. However, you should see 

a doctor immediately if you develop symptoms such as high fever, confusion, muscle 

weakness, severe headaches, and stiff neck or if your eyes become sensitive to light. 

Patients with mild symptoms should recover completely and do not require any 

specific medication or laboratory testing. 

 

Q: Should I report dead birds to the Health Department? 

A: Yes. DOHMH encourages New York City residents to report all dead bird sightings 

within NYC, especially crows and blue jays. This will assist us in our efforts to 

monitor possible WN virus activity. However, while every report is important to our 

monitoring efforts, we will be collecting only a sample of the dead birds and not

every dead bird reported. If you do not receive a phone call from DOHMH to arrange 

pick up of the dead bird within two business days of making the report, please dispose 

of the dead bird. While there is currently no evidence that West Nile virus can be 

spread directly from birds to people, dead birds can carry other diseases and, 

therefore, should never be handled with bare hands. Use gloves to carefully place 

dead birds in double-plastic bags and then place dead birds in the outdoor trash. 

For more information about West Nile virus, call the New York City Citizen Service 

Center, 24 hours a day, seven days a week, by dialing 311. TTY/TDD is available by 

dialing (212) 504-4115; or check the DOHMH Website at nyc.gov/health. 
New York City Department of Health and Mental Hygiene 

2006 Comprehensive Mosquito Surveillance and Control Plan 

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GLOSSARY 

 

 

adulticide a type of pesticide used to kill adult mosquitoes 

Aedes sollicitans See Ochlerotatus sollicitans 

Altosid brand name of methoprene, a type of larvicide 

arbovirus shortened term for arthropod-borne virus, a virus that is 

carried by arthropods 

arthropod a group of an animal that does not have a backbone and 

have jointed walking appendages, such as insects, spiders 

and lobsters 

Bacillus sphaericus a bacterium; type of biological pesticide used to control 

mosquito larvae in water (mosquito larvae die after 

ingesting this bacteria) 

Bacillus thuringiensis a bacterium; type of biological pesticide used to control

var. israelensis (Bti) mosquito larvae in water (mosquito larvae die after

ingesting this bacterium); bacteria found in Mosquito 

Dunks® 

bridge vector an arthropod (in this case, a specific species of mosquito) 

that serves as a main transmission of virus between the 

reservoir (birds) and humans. 

catch basins grates seen at street corners and in other properties for 

water runoff 

Culex pipiens a species of mosquito, the primary vector for West Nile 

virus, commonly found in urban areas; breeds in fresh, but 

stagnant water, such as backyard containers and storm 

drains 

DEET DEET (chemical name, N,N-diethyl-meta-toluamide) is the 

active ingredient in many insect repellent products 

Eastern equine mosquito-borne viral disease that causes inflammation of

Encephalitis (EEE) the brain; similar to West Nile 

encephalitis inflammation of the brain, which can be caused by 

numerous viruses and bacteria, including West Nile virus 
New York City Department of Health and Mental Hygiene 

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Environmental Impact A document that describes the impact on the environment

Statement (EIS) from a proposed action (in this case, the application of 

pesticides to control adult mosquitoes). 

gravid traps mosquito traps designed to attract pregnant female 

mosquitoes 

Interactive Voice System an automated telephone system by which information can 

be accessed by choosing from a set of options 

larvae immature mosquitoes that live in water; stage which 

hatches from the egg, prior to adult stage 

larvicide a type of pesticide used to control immature or larval 

mosquitoes 

light traps mosquito traps outfitted with a light to attract mosquitoes 

malathion an organophosphate pesticide used to control adult 

mosquitoes; active ingredient in the product Fyfanon® 

meningitis inflammation of the lining of the brain and spinal cord that 

can be caused by a virus or bacteria 

methoprene a type of insect growth regulator used to control larval 

mosquitoes; it prevents mosquito larvae from emerging and 

developing into adult mosquitoes 

mosquito breeding site a location where mosquitoes lay eggs, usually in stagnant 

water with organic material 

mosquito pools a group of mosquitoes of the same species, collected in 

given area and combined at the laboratory for testing for 

the presence of West Nile and related viruses 

naled an organophosphate pesticide used to control adult 

mosquitoes 

neurology the study of the nervous system and its disorders 

Ochlerotatus sollicitans species of mosquito that breeds in salt marshes 

outbreak an unexpected increase in frequency or distribution of a 

disease 

permethrin a synthetic pyrethroid pesticide used to control adult 

mosquitoes; active ingredient in the product Biomist® 
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pesticide substance used to kill pests such as insects, mice and rats; 

an insecticide is a form of pesticide 

piperonyl butoxide An additive to pyrethroid pesticides that improves the 

effectiveness of the active ingredient 

resmethrin a synthetic pyrethroid pesticide used to control adult 

mosquitoes; active ingredient in the product Scourge®

salt marsh areas of vegetation in bodies of salt water that may support 

the breeding of certain types of mosquitoes such as 

Ochlerotatus sollicitans; example of salt marshes is 

Jamaica Bay. 

sentinel an early warning system, in this case, for the presence of 

virus (e. g. , sentinel chickens) 

serologic of, or relating to, serum 

source reduction the removal or reduction of larval mosquito habitats 

St. Louis encephalitis (SLE) mosquito-borne viral disease that causes inflammation of 

the brain; very similar to West Nile virus 

sumithrin a synthetic pyrethroid pesticide used to control adult 

mosquitoes; active ingredient in the product Anvil 10+10®

VectoBac brand name for the larvicide Bacillus thuringiensis var. 

israelensis (Bti)

VectoLex brand name for the larvicide Bacillus sphaericus

vector an organism (an insect in most cases) capable of carrying 

and transmitting a disease-causing agent from one host to 

another 

viral of, or relating to, a virus 

viral encephalitis inflammation of the brain caused by a virus, such as West 

Nile virus