1. Mosquito-borne Diseases Western equine encephalitis and St. Louis encephalitis Both have occurred...

Mosquito-borne DiseasesMosquito-borne Diseases

Western equine encephalitis and St. Louis encephalitis

Both have occurred in Washington but no reported cases since early 1980’s

West Nile virus – Detected in 1999 in New York City– Detected in Washington and 43 other

states in 2003– Continued surveillance effort in

Washington

22

Mosquito-borne Disease Mosquito-borne Disease SurveillanceSurveillance

Pre-1960’s No record of state activity

1960’s First statewide mosquito survey published in 1966

1960’s Mosquito Control Districts formed in Eastern Washington

1970’s Sentinel flocks used in Benton County and Grant County

33

Mosquito-borne Disease Mosquito-borne Disease SurveillanceSurveillance

1980’s Last confirmed human and horse cases of mosquito-borne

encephalitis

1990’s Zoonotic Disease program established in DOH

2001 DOH initiates WNV surveillance

44

Yakima Valley Encephalitis Yakima Valley Encephalitis OutbreaksOutbreaks

1939 31 cases

1940 58 cases 13 fatal



(Reported in August 1945 Journal of American Medical Association)

55

Spokane

San JuanIsland

Pierce

King

Snohomish

Skagit

Whatcom

Clallam

Jefferson

GraysHarbor

Thurston

Kitsap

Clark

Cowlitz

Lewis

Skamania

Wahkiakum

Mason

Yakima7 Cases ( 6 WEE, 1 SLE)

Chelan

Okanogan

Ferry Steven

s

PendOreille

Lincoln

Kittitas

Whitman

Klickitat

Benton

Walla Walla

Columbia

Garfield

Asotin

Franklin

Adams

Grant

Douglas

Pacific

Reported Human Cases of Mosquito-borne Reported Human Cases of Mosquito-borne Disease (1970-1982) Disease (1970-1982)

Western Equine EncephalitisSt. Louis Encephalitis

Total cases = 12 66

Spokane

San JuanIsland

Pierce

King

Snohomish

Skagit

Whatcom

Clallam

Jefferson

GraysHarbor

Thurston

Kitsap

Clark

Cowlitz

Lewis

Skamania

Wahkiakum

Mason

Yakima

Chelan

Okanogan

Ferry Stevens

Pend Oreille

Lincoln

Kittitas

Whitman

Klickitat

Benton

Walla Walla

Columbia

Garfield

Asotin

Franklin

AdamsGrant

Douglas

Pacific

Western Equine Encephalitis Horse CasesWestern Equine Encephalitis Horse Cases(1953-1983)(1953-1983)

Suspect casesSuspect cases

Confirmed casesConfirmed cases77

West Nile VirusWest Nile VirusIn the United StatesIn the United States

88

WNV BackgroundWNV Background

• First isolated in the West Nile District of Uganda, 1937

• Recognized as a cause of inflammation of the spinal cord and brain with outbreak in elderly patients, Israel, 1957

• Equine disease noted in Egypt and France in the early 1960s

• 1999 “Old World” virus arrives in the “New World”

99

West Nile OutbreaksWest Nile Outbreaks

Israel Israel 1951-1954, 1957, 2000-20021951-1954, 1957, 2000-2002France France 1962, 20001962, 2000South Africa South Africa 19741974Romania Romania 1996-19971996-1997Italy Italy 19971997Czech Republic Czech Republic 1998 1998 Republic of the Congo 1998 Republic of the Congo 1998 Russia Russia 19991999United States United States 1999-20021999-2002

1010

Outbreak TimelineOutbreak Timeline

Israel 1957

Uganda 1937

Israel 1951-

54

France 1962

South Africa 1974

Romania 1996 Italy 1997 Czech Rep. 1998 Congo 1998 Russia 1999 US 1999-2002 Israel 2000-2002 France 2000

Encephalitis Condition Identified

Equine Disease Identified

1111

Incidental infections

Bird reservoir hosts

Incidental infections

West Nile Virus Transmission CycleWest Nile Virus Transmission Cycle

Mosquito vector

1212

WNV in the US WNV in the US Speculated Pathways of IntroductionSpeculated Pathways of Introduction

• Human-transported birdHuman-transported bird• LegalLegal• IllegalIllegal

• Human-transported mosquitoesHuman-transported mosquitoes• Storm-transported birdStorm-transported bird• Intentional introduction (terrorist event)-Intentional introduction (terrorist event)-

not likelynot likely• Infected human traveler-not likelyInfected human traveler-not likely

1414

The incubation period for West Nile Virus is generally 3-14 days following a bite from an infected mosquito.

WNV SymptomsWNV Symptoms

• High Fever• Headache and body aches• Skin rash• Swollen lymph glands• Neck stiffness• Disorientation• Convulsions

1515

States with WNV (0)States with WNV (0)

Distribution of WNV Before 1999Distribution of WNV Before 19991616

States with WNV (4)States with WNV (4)

Distribution of WNV as of November 1999Distribution of WNV as of November 1999

1717

States with WNV (12 + DC)States with WNV (12 + DC)


1818



1919



2020

WNV 1999-2002 by CountyWNV 1999-2002 by County2121

Distribution by County December 7, 2002Distribution by County December 7, 2002

Source: Dr. Henry Huang, Washington U. School of Medicine Source: Dr. Henry Huang, Washington U. School of Medicine

2222

San Juan Island

Clallam

Jefferson

GraysHarbor

Kitsap

Lewis

Skamania

Pacific

Mason

Ferry

Stevens

Lincoln

Kittitas

Klickitat

Columbia

Garfield

Asotin

Okanogan

Snohomish

Douglas

Chelan

Spokane

Yakima

Whatcom

Pierce

Franklin

Benton

Whitman

Walla Walla

Clark

Cowlitz

Thurston

Wahkiakum

PendOreille

Grant

Adams

King

Counties Detecting West Nile Virus 2002Counties Detecting West Nile Virus 2002

Skagit

2323

Case Summary 1999-2002Case Summary 1999-2002

YearHumans (deaths)

Horses (deaths)

2002 4,161 (277) 14,717

2001 66 (9) 470 (156)

2000 21 (2) 60 (23)

1999 62 (7) 25 (8)

2727

*As of Dec 19

1999-2000 2001 2002*

Cases 83 66 3,852

Age Median 65 68 55

Age Range 5-90 yr 19-90 yr 1 mn-99 yr

Males 54% 65% 54%

Fatality Rate 11% 14% 6%

Fatality Age 78 (24-99 yr)

WNV Case-Patient Demographics & WNV Case-Patient Demographics & Mortality United States, 1999-2002*Mortality United States, 1999-2002*

2828

Date of Symptom Onset, West Nile VirusDate of Symptom Onset, West Nile VirusUnited States, 1999-2001United States, 1999-2001

0

5

10

15

20

25

30

7/7

8/4

9/1

9/29

10/2

711

/24

12/2

3

Week ending

Nu

mb

er

of

ca

se

s

2001

2000

1999

2929

Protecting Public HealthProtecting Public Health

• Surveillance

• Personal Protection and Education

• Mosquito Control

3030

WNV SurveillanceWNV Surveillance

• Mosquitoes • Dead birds (especially crows, jays,

ravens and magpies)• Veterinary surveillance• Human surveillance

3131

Mosquito SurveillanceMosquito Surveillance

• Review information on species in your jurisdiction

• Establish system for recording “mosquito complaints”

• Identify and map breeding locations• Conduct larval/adult surveillance

(May-Sep)

3232

Dead Bird SurveillanceDead Bird Surveillance

• Establish system for recording dead bird reports

• Message to public on reporting sightings

• Submit corvids for analysis (May-Oct)

• Response protocol for positive birds

3333

Horse Case SurveillanceHorse Case Surveillance

• Encourage reporting by local veterinarians

• Identify major stables, training facilities and establish contact

• Track cases as they occur• Response protocol for sick, dead

horses

3434

Human Case SurveillanceHuman Case Surveillance

• Enhanced passive surveillance May-Sep

• Active surveillance when cases result

• Case investigation to help define probable exposure

• Response protocol for illness or death in humans

3535

Mosquito ControlMosquito Control

• Assessment of local capability• Designation of lead agency, person

(where, when, how)• Develop local action plan• Training and licensing of personnel

to use mosquito control compounds• Keep community involved and

informed in the decision process, especially if adulticiding is considered

3636

WNV Mosquito Species in WNV Mosquito Species in WashingtonWashington

Aedes cinereusAedes vexans Culex pipiens Culex restuansCulex tarsalisAnopheles punctipennisCoquilletidia perturbansOchlerotatus canadensisOchlerotatus japonicus

Counties (39)222728 1352610 5 1

3737

Human cases

Veterinary cases

Mosquitoes

Dead birds

Time

Dis

ease

Act

ivit

y

Sentinel hosts

Estimated Sensitivity of WNV Estimated Sensitivity of WNV Surveillance MethodsSurveillance Methods

3838

Personal ProtectionPersonal Protection

• Wear long sleeves & pants in mosquito-infested areas

• Use repellant containing DEET (N,N-diethyl-3-methylbenzamide) and follow directions carefully

• Limit outdoor activities at dawn and early evening

• Repair holes in door & window screens

3939

Habitat ReductionHabitat Reduction

• Eliminate standing water (flower pots; tires; wheelbarrows; wading pools)

• Change the water in birdbaths at least weekly

• Aerate and chlorinate swimming pools and hot tubs; cover if possible

• Consider mosquito-eating fish for your pond

• Keep gutters clean to prevent standing water

• Spread the word: educate your friends and neighbors

4040

Washington State

Washington State Department of Health

response to threats of arbovirus, such as

West Nile virus transmitted to humans

by mosquitoes.

November 2002

M osquito-borne Disease Response P lan

4141

Want More?Want More?

www.doh.wa.gov/wnv www.cdc.gov www.cfe.cornell.edu/erap/WNV/ www.mrsc.org/subjects/governance/spd/

mosquito.aspx Your local health department

4242

1. Mosquito-borne Diseases Western equine encephalitis and St. Louis encephalitis Both have occurred...

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