Washington County Arbovirus Management Program 2008 Year End Report Page 1 of 12 

# WASHINGTON COUNTY

OREGON

Department of Health and Human Services Environmental Health Division

A RBOVIRUS 

### M ANAGEMENT 

### P ROGRAM 

### 2008 Year End Report

BACKGROUND

The Washington County Arbovirus Management Program was initiated in 2003 in anticipation of the arrival of West Nile Virus (WNV) in Oregon. The current program is a cooperative effort between Washington County and Clean Water Services (CWS), Tualatin Hills Park and Recreation District (THPRD), Beaverton School Dist rict, and local cities. Efforts are formalized through Intergovernmental Agreements (IGA). Participating cities include Beaverton, Cornelius, Forest Grove, Hillsboro, Tigard, Tualatin, a nd Sherwood. The Washington County program focuses on education, surveillance, and controlling mosquito larvae capable of vectoring disease to humans. Washington County will only consider managing adult mosquito populations through adulticide applications in the event of a public health emergency.

SURVEILLANCE IN 2008

The Washington County Arbovirus Management Program conducted active larval and adult mosquito surveillance in 2008. Washington Count y field workers and IGA field staff inspects over 1300 potential mosquito habitats (see map 1). Field workers collected mosquito samples for identification and encephalitis testing, documented potential habitat breeding locations, presence of mosquitoes at sites and evaluated habitat risk for mosquito production. Larval and adult mosquitoes were collected on a weekly basis from selected sites in Washington County using aquatic dippers and Gravid or Encephalitis Virus Surveillance (EVS) CO2 traps. Washington County program staff identified and tested mosquitoes for WNV. Species known to be capable of transmitting WNV were pooled into all female, single species, single site samples and tested for WNV by the County utilizing the Rapid Analyte Measurement Platform (RAMP) (see table 1). Washington County tested 31 mosquito pools (5,999 individual female adults); all mosquito pools tested were negative. 93% of the adult and 79% of the larval samples collected were species considered either “most” capable or “moderately” capable of transmitting WNV.AVIAN SURVEILLANCE IN 2008

Washington County also conducted passive avian surveillance. Avian specimens collected for testing were first tested for WNV by the County utilizing RAMP testing equipment. Confirmation testing was done through Polymera se Chain Reaction (PCR) testing conducted by the Oregon State University (OSU) Veterinary Diagnostic Laboratory (VDL).

Washington County collected 25 dead birds in 2008 (see map 2). Ten of these birds were subsequently submitted to Oregon State University Veterinary Diagnostic Laboratory for confirmation testing. No bird tested positiv e for WNV by PCR confirmation testing by OSU VDL. 56% of the birds collected were crows (see table 2).

PUBLIC REQUESTS FOR INFORMATION IN 2008

Washington County answers public inquiries as pa rt of their community outreach program. In 2008, the County received more than 50 calls from the public concerned about mosquitoes and/or WNV (see map 3): 3⁄4 11 complaint calls related to the sighting of sick/dead birds 3⁄4 37 calls related to larval and adult mosquito nuisances or the presence of standing water 3⁄4 In addition calls related to sick/dead birds and other vector inquiries were also received

LARVAL MOSQUITO CONTROL IN 2008

Mosquito control efforts in Washington County focused on larval breeding in catch basins located within the 118 square mile urban growth boundary. Larval mosquito surveillance over the past three years has shown that catch basins are a significant source of mosquitoes in urban areas of Washington County. Washington County and IGA field staff coordinated efforts to control mosquito populations by treating public catch basins once during the mosquito season. In 2008, Washington and IGA field staff treated 21,975 sumped catch basins with Altosid XR Briquets (see table 3 and map 4).

In 2008, Washington County’s program continued to identify and treat high-risk natural habitats for mosquito larvae. Surveillance was conducted at these sites and treated, as needed, by Washington County staff (see map 5). Surveillance and treatment efforts in high-risk natural areas have been increased.

Washington County Arbovirus Management Pr ogram 2008 Year End Report Page 2 of 12EDUCATION EFFORTS IN 2008

The following educational program activities took place in Washington County’s WNV Prevention program in 2008: 3⁄4 Health Fairs - plant nurseries, city events, employers, public and private Schools, public libraries, organizations (Kiwanis, Elks, Boy Scouts, Familias Hispanas, Churches Americans with Disabilities Group) 3⁄4 Speaking engagements: organizations (Boy Scouts, Kiwanis, Adelante Mujeres, Centro Cultural, Citizen Participation Groups), long term care facilities 3⁄4 OMSI 3⁄4 Washington County Fair 3⁄4 Migrant camps 3⁄4 Children’s Clean Water Festival 3⁄4 Farmer’s markets 3⁄4 Parks and Recreation facilities

Materials, which included bookmarks, brochures a nd promotional items, were distributed at the above and below listed events/locations. 3⁄4 Public Libraries 3⁄4 Pharmacies and Homeowner Associations 3⁄4 County Public Services Building Foyer 3⁄4 Beaverton Resource Center 3⁄4 Beaverton Health Clinic 3⁄4 Hillsboro Health Clinic

GAMBUSIA AFFINIS DISTRIBUTED TO PUBLIC IN 2008

In 2008, Washington County distributed Gambusia a ffinis (Mosquito fish) to county residents to help mitigate mosquito production in aquaria sites. 537 mosquito fish were distributed to 31 County residents (see map 6).

ADDITIONAL PROGRAM ACTIVITIES IN 2008

Improvements in 2008, to Washington County’s Mosquito program include:

3⁄4 Creation of a more robust and complete mosquito surveillance program by expanding adult trap locations

3⁄4 Washington County also took steps to begin tr eating private catch basins by identification and treatment of public common areas such as strip malls, business parks, colleges, etc. This activity will continue for the 2009 treatment season.

Washington County Arbovirus Management Pr ogram 2008 Year End Report Page 3 of 12Washington County Arbovirus Management Pr ogram 2008 Year End Report Page 4 of 12TABLE 1: Mosquito Species Collected in Washington County 2008

Species breakdown of mosquito larvae and adults collected

Larval Mosquito Totals Adult Mosquito Totals Species Total Species Total Ae vexans 42 Ae vexans 924 An freeborni 1 An punctipennis 55 An punctipennis 25 An freeborni 12 Cs impatiens 1 Cq perturbans 8 Cs incidens 500 Cs incidens 68 Cs inornata 9 Cx erythrothorax 13 Cs minnesotae 40 Cs particeps 9 Cs particeps 12 Cs inornata 20 Cx boharti 118 Cs minnesotae 367 Cx erythrothorax 21 Cs impatiens 2 Cx pipiens 3155 Oc washinoi 1 Cx stigmatosoma 35 Cx pipiens 6029 Cx tarsalis 250 Cx tarsalis 406
Cx territans 127 7914 Unknown 61
4397

Washington County Arbovirus Management Pr ogram 2008 Year End Report Page 5 of 12Washington County Arbovirus Management Pr ogram 2008 Year End Report Page 6 of 12TABLE 2: Birds Tested in Washington County 2008

Type of birds collected, confirmed test results, a nd specimen location in Washington County by zip code.

Bird Type Test Result Zip Code of Tested Specimen

Crow Negative 97224

Crow Negative 97008

Crow Negative 97124

Other Negative 97123

Robin Negative 97062

Crow Negative 97223

Crow Negative 97223 Jay Negative 97007 Jay Negative 97229

Unknown Negative 97007

Washington County Arbovirus Management Pr ogram 2008 Year End Report Page 7 of 12Washington County Arbovirus Management Pr ogram 2008 Year End Report Page 8 of 12TABLE 3 : Sumped Catch Basins Treated in Washington County 2008

Number of catch basins treated by Washington County and IGA field partners in Washington County.

Sumped Catch Basin Treatment in Washington County for 2008

Agency that treated sumped catch basins in 2008 Number of Sumped catch basins treated City of Beaverton 2,716 City of Forest Grove 541 City of Sherwood 1,673 City of Tigard 2,230 City of Tualatin 1,300 Clean Water Services 6,871
Cornelius Public Works 998
Beaverton School District 501
Hillsboro Public Works 4,311
Hillsboro Parks 550

Tualatin Hills Parks and Recreation District 80 Washington County WNV Program+ WC Facilities 1506
TOTAL SUMPED CATCH BASINS TREATED 23,277

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