1. Mosquito-borne Diseases Western equine encephalitis and St. Louis encephalitis Both have occurred...
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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
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Yakima Valley Encephalitis Yakima Valley Encephalitis OutbreaksOutbreaks
1939 31 cases
1940 58 cases 13 fatal
1941 26 cases 3 fatal
1942 28 cases 2 fatal
(Reported in August 1945 Journal of American Medical Association)
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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”
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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
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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
1313
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
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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)
Distribution of WNV as of November 2000Distribution of WNV as of November 2000
1818
States with WNV (27 + DC)States with WNV (27 + DC)
Distribution of WNV as of November 2001Distribution of WNV as of November 2001
1919
States with WNV (44 + DC)States with WNV (44 + DC)
Distribution of WNV as of November 2002Distribution of WNV as of November 2002
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
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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
2424
2525
2626
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