# Presentation: 232695

## Sustaining Surveillance for West Nile Virus in New York City,

**Sustaining Surveillance for West Nile Virus in New York City,**
**1999-2004**
**Annie Fine, MD**
**New York City Department of Health and Mental Hygiene**

**Notes:**
I want to thank you, the audience, and John Roerhig and all the Fort Collins folks for inviting me to speak today.  It is truly a pleasure.  It is a special pleasure for me, since though I’m sure many of you in the audience have heard me talk before at these conferences, this is actually the first time I’ve been ASKED to talk.

## From hysteria

**to humdrum**

**Notes:**
Ok – so what can we learn from what has happened in New York City.  We have gone, in six short years, from WN hysteria, click, and now, click to humdrum

## 1999

**Notes:**
This is an example of what we faced in 1999

## 2004

**Notes:**
And this, in 2004, one of the few articles run by the New York Times last year, read...

## Human Cases of WNND and Number of New York Times Articles on WN virus, NYC, 1999-2004

**Notes:**
This slide shows media coverage from just one newspaper, the NY Times, from 1999 to 2004, with the number of WN human cases – showing a marked increase from 1999 to 2000 and then a steady decrease.  The dip in 2001 is likely due to increased media coverage starting in September of the 9-11 related events and anthrax attacks.  Now, in 2004, we barely can get any coverage of local West Nile, even in community papers.  Most of the 16 articles published in 2004 were national news pieces or features, covering WN outside of New York City.

## Challenges in Sustaining Surveillance and Control as WN becomes endemic

- Decreased funding
- Uneven medical provider awareness and reporting
- Decreased media interest
- Waning public interest/awareness
- Need to balance WN morbidity and mortality with other public health priorities
- WN virus still unpredictable and can cause outbreaks

## Specific Concerns for Large Cities

- Need for rapid response capacity – dense population increases potential risks of outbreak
- Need for fine texture in determining risk to humans
- Need for very judicious use of adulticide
- Avoid exposure of large numbers of people unnecessarily
- Community/environmental sensitivity or opposition
- Diverse population
- Need to “do everything” – public health is local

## Federal Funding to NYC for West Nile Virus Surveillance (ELC $), and human WNNDFiscal Years 1999-2004

**Notes:**
The blue bars in this slide show human cases of West Nile neuroinvasive disease in New York City from 1999 through 2004, and federal support for WN activities in the black line – you can see that our numbers are relatively small compared to some of the subsequent outbreaks in the midwest and west, but that though we had hoped WN would go away, it really hasn’t.  Our “worst” year since 1999 was actually 2003.  Also, what this doesn’t show is that the epicenter of WN has moved around in the City a bit, but certain areas, such as Staten Island and northeastern Queens, do remain at relatively high risk, and WN seems to recur there almost every year.  New York City had no mosquito control program at all in 1999, and spent only emergency funds that year on WN surveillance and control.  In response to that crisis, we received a large amount of federal funding for WN activities in 2000, over 2 million dollars, and used that to establish a comprehensive mosquito surveillance and control program.  But soon after, as our case count fell, and WN appeared elsewhere, so did federal dollars, dropping about 75% in the next 3 years.

## NYC DOHMH expenses for arbovirus surveillance and control*, FY 99-04

***Does not include in kind services for human surveillance and other **
**activities; also does not include non-DOH agency spending.**

**Notes:**
We were very grateful for the federal funding in 2000 that enabled us to quickly build up our program.  Yet the program needs to be sustained, and our expenses have not decreased much since 2000, as you can see here.  This slide depicts expenses just for the arbovirus surveillance and control program, including the lab, from 1999 through 2004 – and does not include many in kind services such as human surveillance and operational support.   So we have needed to use a combination of city funds, some state funds for control, leverage other sources of support, and use creative and strategic operations to continue to do what we need to do to protect the public health.

## Surveillance - Human

- Maintaining provider awareness and reporting is a challenge –
- Still emphasize reporting and testing of hospitalized cases and WNND
- Few requests for grand rounds
- Use health alert system
- Clinical presentation of WN may be subtle, need to “think WN”
- Many hospital-based providers were not here in 1999
- NYC still actively manages suspect cases – still emphasize timely detection
- Offer free testing and free transportation of specimens to City PHL
- Little commercial testing in NYC
- Rolled into general disease surveillance
- Ended active surveillance

**Notes:**
I will touch upon all the various types of surveillance we do.  First human.  The biggest challenge, after 6 years, is maintaining provider awareness and reporting.  Just as background - we still emphasize reporting of hospitalized cases, or neuroinvasive disease.  This is for several reasons.  First, is really habit and circumstance.  in New York City, there was no commercial testing available in 1999 and 2000, so to do good surveillance, and timely detection of human cases, we felt we had to offer free local testing so we didn’t have to send specimens out and wait for results.  So we offered that to the medical community, but asked that they limit it to hospitalized patients so the lab did not get inundated.  Doctors in New York City have gotten used to this and do not order much commercial testing for outpatients.  Also, the resources to investigate non-hospitalized cases if we did encourage identification of them would probably overwhelm us and would not provide data that was timely enough for us to use for control efforts.  (mention that results come back with no patient address, only an MD name).  Now, we get very few requests for talks on West Nile. We primarily use our health alert system to enhance awareness every year and update clinicians on what is going on.  But we do know we are missing cases.  WN may have a very subtle clinical presentation, and physicians need to “think West Nile” in order to diagnose it, just as they did with TB in the 1990’s.  Mention Debby Asnis.  Many hospital based providers in New York City were not here in 1999, and have lower awareness of the illness and its manifestations because of that.  We still actively manage suspect cases, which number anywhere from 400 to 800 per season, because we still desire timely detection.  So we offer free testing and free transport of specimens to our City Public Health Laboratory.  We have no designated funds for human surveillance and have tried to “normalize” it as much as possible, rolling it into our general disease surveillance activities, except that we have maintained a separate database.  We tried active surveillance for a few years but found that it did not add much so have ended it.

## Surveillance – Human (cont.)

- Since WN 1999 we have greatly improved surveillance data for aseptic meningitis and encephalitis, pick up other outbreaks
- Shared database with lab serves as model for other outbreak investigation databases

**Notes:**
A side benefit of WN has been that we now have far improved data on encephalitis and aseptic meningitis, and we are able to pick up other outbreaks, especially of enterovirus.  Lucky us...  Also, our shared database with the lab has served us very well, and is being used as a model for new outbreak investigation databases are currently creating to allow rapid data collection and analysis in a complex or large outbreak.

## Aseptic Meningitis by Month, New York City, 1989-2004

**Notes:**
Aseptic meningitis is reportable in New York City, and this slide, which shows counts of aseptic meningitis from 1989 through 2004, just highlights the dramatic change in our surveillance data for aseptic meningitis since WN arrived in 1999 (point), with much more complete reporting every year now.

## Slide 13

**Notes:**
Same for encephalitis, which was hugely underreported before 1999.

## Surveillance - Mosquitoes

- Dense network of traps (83 permanent trap sites per week, 111 supplemental trap sites) over 321 square miles
- Over 221,000 mosquitoes ID’d in 2004
- 10,687 pools tested in 2004
- 184 pools infected with WN virus
- Probably “best” measure of risk to humans, but still hard to quantify
- Consider sampling strategies

**Notes:**
Turning to mosquito surveillance, which is really the mainstay of our WN surveillance program.   We have a sort of experiment going in New York City, which is to see how many mosquito traps we can set before we catch a human.  No seriously, we have a very dense network of traps – 83 permanent trap sites are set per week during the season, and then these are supplemented – last year at 111 different sites – when we have some evidence of disease activity in an area.  These traps cover a relatively small geographic area, only 321 square miles – so you can see that there is at least 1 trap for every 4 square miles.  So we get reams of mosquitoes, over 221,000 were ID’d last year alone.  And lots to test – 10,687 pools.  And reliably, we always find West Nile.  Last year we had 184 positive pools.  Our mosquito data is probably the best measure we have of risk to humans, but it is still hard to know how to quantify it for real time surveillance purposes, and how to interpret it.  We simply cannot spray every time we get a positive pool.  Also, mosquito surveillance, as you can see, is extremely labor intensive, and so now we are actively considering sampling strategies so that we do not have to ID and test every mosquito.

## West Nile Virus Activity In New York City (2004)

**Brooklyn**

**Queens**

**Staten Island**

**Manhattan**

**Bronx**

**Notes:**
tI have to thank Farida Mahmood for lending me this complicated slide summarizing our surveillance data for 2004 – which I will walk you through a bit.  Just to give you a sense of how complicated it can be to try to interpret the wealth of surveillance data we gather each year and try to understand how we can use it to predict human risk and our target mosquito control efforts.  In red, you can see the positive mosquito pools, with the larger red circles indicating repeatedly positive trap sites – these are most prominent in Staten Island.  The blue stars represent positive dead birds – and are also most prominent in Staten Island, but are present throughout much of Queens and the Bronx.  Yet despite this, we had only one locally acquired neuroinvasive case in 2004, here.  Mystifying how we can have so much virus, and only one case. Maybe we should have a private conference with Yuma County...

## Surveillance – Dead Birds

- Value for targeting control measures unclear
- Early warning system
- In densely populated area, can you use dead bird data to pinpoint areas of higher risk?
- Reported dead bird clusters in space and time - data has not proven extremely helpful in targeting control, though used for enhancing surveillance
- Value of dead bird data may change over time
- Dependent on public reporting (311, website)
- Changing seroprevalence in resident or migrant populations
- Depletion of corvids
- Turn around time is critical to usefulness but NYC discontinued in house bird testing due to costs, ltd lab capacity
- May need to reduce these activities substantially

**Notes:**
Dead bird data is also difficult to interpret, and it’s value for targeting control measures remains unclear.  We do use it as an early warning system, but we hardly need warning any more since we expect that WN is going to appear each year.  The important question is whether we can use dead bird data to pinpoint areas of higher risk.  In addition to looking for positive birds, we have tried using fancy analyses to identify clusters of reported dead birds in space and time.   And disappointingly, the cluster data hav not proven extremely helpful in targeting control, mostly because such large areas of the city are implicated, as you will see in the next slide.  We do use bird clusters to enhance surveillance and larviciding.  Dead bird data may lose its value over time – it is highly dependent on public reporting, and therefore on public interest and awareness (NYC in 2003 instituted a new system for reporting through 311, and despite this, the number of dead bird reports fell dramatically in 2004, probably due to combination of lower WN activity, lower public awareness, and possibly increasing immunity in the bird population.) Also, dead bird reporting may change due to increasing immunity of resident or migrant populations, or depletion of susceptible species.  Turn around time for testing is critical to having bird data be useful to us, but we did try in house testing for one year, but it was cut due to costs and limited lab capacity.  So it is possible we may need to reduce bird surveillance substantially if it does not prove to be more useful in the next couple of years.

## Dead bird reports, positive dead birds, NYC, 2000-2004

**Notes:**
This slide just illustrates a decline in the number of dead bird reports we have received since 2000, and a concomitant decline in the proportion of infected birds among those tested, dropping to only 5.9 percent last year, from 40.7% in 2004.  Hard to know if this means less virus around or if the bird population has changed.  We do not believe the marked drop in 2004 is due to dropping public interest in reporting since reports of standing water, which we also get via the City’s 311 system, did not drop in 2004 at all.

## Slide 18

**Notes:**
This slide shows an example of a mid-season map depicting dead bird clusters in tan and red, with darker colors indicating the number of times a particular area has been included in a dead bird cluster, positive dead birds, in the red dots, and human cases as blue stars, which as you can see, though they do seem to occur in some relationship to the dead bird clusters, are not highly related to the areas with most intense clustering.  Also, the clusters cover a very large area of the city – this area is large enough that we could not justify adulticiding it all, so we just use the clusters now to enhance surveillance, and as an adjunct to other indicators.  Also note the apparent lack of a strong correlation of positive dead birds with human cases.

## Slide 19

## Analysis of Surveillance Data

- Not simple – tried time space cluster detection methods, ROC curves, other complex methods
- Will likely need to look at combinations of indicators rather than a single indicator
- Most critical need is for expert data analysis of the wealth of data we have gathered, both in NYC and in other large cities
- People, like birds, do move around, and in a densely populated area, using human cases as the outcome measure may make risk assessment even more difficult.

**Notes:**
Analysis of our surveillance data is critical.  It is not simple.  We have tried a bunch of sophisticated analytic models, but so far nothing has emerged as a reliable quantitative indicator of risk.  We will likely need to look at combinations of indicators.  There is a critical need for expert data analysis...  

## Mosquito Control

- In urban area, especially where unaccustomed to mosquito control activities, adulticiding needs to be targeted and used judiciously
- Heavy emphasis on larviciding
- Catch basins
- Green areas, cemeteries
- Aerial
- Proactive pesticide resistance management
- When to use adulticide – NOT straight-forward, controversial and difficult to evaluate effectiveness
- Qualitative algorithm
- Still some subjective elements, especially in determining boundaries of spray zones

**Notes:**
Good news is that explicit and prominent opposition by environmentalists has lessened, partly because protests do not draw media attention now, and because the public has become more used to the idea of sporadic spraying.  However, we still spray in small areas, and only once (not repeated over several weeks), and we do not know the effectiveness of this technique in reducing mosquito populations over time.  Effectiveness measured one to several days following adulticides has shown effectiveness in the range of 59%, but is very inconsistent across spray events.

Persistence of positive mosquito pools, population density dynamics of mosquitoes, historical WN activity, positive neighboring trap, human population at risk, mosquito species

## Adult Mosquito Control, NYC, 1999 - 2001

**In 2001**, there were only 6 spray events in 3 boroughs.  Spraying was targeted to areas of WNV detection in birds, mosquitoes, and humans. Different colored areas reflect treatments on different nights from 8/14/01-9/2/01.

**In 2000,** most of the City was treated by ground or by air.  Spraying occurred within a 2 mile radius of WNV positive dead birds. Different colored areas reflect treatments on different nights from 7/19/00-9/24/00.

**In 1999**, the whole City was treated twice by air (outer boroughs) and truck (Manhattan). Parts of northern Queens and southern Bronx were treated 4 times.

- 1999

- 2000

- 2001

## 2004

**Notes:**
Moderated and more consistent approach over subsequent few years – judicious use of adulticide – only spray once, concerns regarding effectiveness of reducing mosquito populations if you do not do repeat applications

## Public Knowledge and Preventive Behaviors

- WN fatigue
- Perception that WN has moved “west”
- Public is used to spraying, environmental activism has died down
- Media does not carry stories
- More challenging to notify the public
- Few resources (and little interest in) for public education campaigns when disease is endemic
- Persistently low levels of knowledge and use of insect repellent – esp. Spanish-speaking

**Notes:**
We performed a street survey of adults ages 50 and up in the spring of 2004.  Over one quarter of Spanish-speaking folks surveyed in the spring of 2004 had not even heard of the West Nile virus, and only 29% knew that the elderly were at highest risk for getting very sick or dying.  Also, only 38% of all those surveyed listed insect repellent as an effective step you could take to reduce your risk of getting West Nile virus, and 71.4% of the elderly over age 70 who were surveyed did NOT use insect repellent at all.  Finally, knowledge of DEET is still very low.  68.7% of all those surveyed who said they used insect repellent did not know whether it contained DEET.

## Public Knowledge and Preventive Behaviors (cont)

- Target education to elderly, during high risk periods
- Have materials in “back pocket”
- Keep message SIMPLE
- Use students – flyers, community groups and elected officials, radio
- Combine the messages – spray notification and high WN activity – use protection
- Offer individuals e-mail notification of spray events
- NOV’s issued for standing water

## Coordination of WN Activities

- Now routine, roles well-defined
- Steering committee meetings once a week during mosquito season, share data
- WN response has served as a learning opportunity and model for DOHMH emergency response system
- $$ currently being used to improve public health emergency response would help in another WN outbreak

**Notes:**
Last, I would like to briefly mention our system for coordinating WN activities.  We have a well-established team, and it is fairly routine for us now.  Our roles are well-defined.  It was interesting hearing about California’s West Nile team going from a cluster of 8 people around a table to over 100 – well in New York we are back to a cluster of 8 around the table.  We hold steering committee meetings once a week during mosquito season and share data.  We have learned a lot from West Nile about how to do emergency response, and though we have faced declining resources, the funds that we have received for BT and emergency response would certainly be used if we had another large WN outbreak

## Balancing West Nile with other Public Health Priorities in NYC

- 2003
- New AIDS diagnoses 			4946
- New HIV diagnoses   			4086
- New TB cases            			1140
- Invasive Pneumococcal Disease 	  944
- Primary and Secondary Syphilis	  531
- West Nile				   30

## Cause-specific Death Rate in NYC, 2000

**0.03**

**Cause-specific Death Rate in NYC, 2000**

**Notes:**
Getting the attention of our public health officials is even challenging now.

## Conclusions

**WN virus has not “gone away.”  Indeed, certain focal areas seem to remain at higher risk (Queens, Staten Island) from year to year**
**As WN becomes endemic, public health needs to oppose dismantling of basic mosquito control programs and be cautious regarding decreasing resources for prevention (TB as a lesson)**
**WN is still unpredictable and difficult to forecast**
**Decisions about adulticiding require more quantitative risk assessment data**
**Local and state HD’s need to be strategic about using designated funds, and leveraging other resources for WN prevention and control**

**Notes:**
We need to critically evaluate the data we have collected and make a determined effort to understand which pieces of surveillance data are the most useful in measuring potential risk to humans, and then focus on those when making decisions about mosquito control and public warning.  This effort should be made over the next few years – in NYC we have collected a wealth of data and would welcome your ideas about ways we can use that to inform the practice of WN prevention.

## Next year in Hawaii

## Acknowledgments

- Waheed Bajwa
- Edgar Butts
- Barbara Edwin
- Jessica Hartman
- Jacqueline Kellachan
- Farida Mahmood
- Farzad Mostashari
- Iqbal Poshni
- Ann Marie Reagan
- Huimin Shen

## 1915 NYC Board of Health Report: "The city can have as much reduction of preventable disease as it wishes to pay for. Public health is purchasable; within natural limitations a city can determine its own death rate." 

## Slide 33

## Slide 34

## Correlation between positive mosquito pools and number of human cases

## μ

**Infected Mosquito Pools Per Site**

**Infected Mosquito Pools (184)**

**Legend**

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**Infected Birds (43)**

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- WNV Infected Birds

**Human Cases (5)**

- 3 Cases, Imported, Arizona.

- 2 Case, New York City.

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**Adulticide Events (14)**

- WNV Infected Mosquitoes

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- August 18, 2004

- September 21, 2004

- September 29, 2004

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- September 14, 2004

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- August 26, 2004

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- 12/06/2004

- West Nile Virus Surveillance

**West Nile Virus Activity and Adult Mosquito Control **

**New York City 2004**

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- July 21, 2004

- August 16, 2004

## Human West Nile Virus in New York City Reported Suspected and Confirmed Cases and RatesJune 1 – Oct 31, 2001-2004*

|  | 2001 | 2002 | 2003 | 2004 |
| --- | --- | --- | --- | --- |
| Total Reports | 511 | 695 | 629 | 836 |
| Suspect WN (meeting criteria*) | 349 
(4.4 per 100,000) | 540 
(7.0 per 100,000) | 479 
(6.2 per 100,000) | 625*
(7.8 per 100,000) |
|    Encephalitis | 148 
(1.8 per 100,000) | 219 
(2.7 per 100,000) | 150 
(1.9 per 100,000) | 134
(1.7 per 100,000) |
|    Aseptic men | 192
(2.4 per 100,000) | 270 
(2.5 per 100,000) | 251 
(3.1 per 100,000) | 429*
(5.4 per 100,000) |
|    Other/Unknown | 11 | 60 | 80 | 80 |
| West Nile Neuroinvasive Disease | 7 
(0.9 per million) | 29
(3.5 per million) | 30
(3.7 per million) | 2
(0.2 per million) |

- *2001-2003:Suspected Case of WN virus = encephalitis and/or unexplained motor weakness compatible with WN viral disease (any age) or aseptic meningitis (> 16 years of age); 2004: Same definition except aseptic meningitis cases of all ages are included.

## Slide 38

** **

## Slide 40