Mosquito borne Diseases

Mosquito-borne Diseases: 

Mosquito-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

Mosquito-borne Disease Surveillance: 

Mosquito-borne Disease Surveillance 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 and Grant County

Mosquito-borne Disease Surveillance: 

Mosquito-borne Disease Surveillance 1980’s Last confirmed human and horse cases of encephalitis 1990’s Zoonotic Disease program established in DOH 2001 DOH initiates WNV surveillance

Yakima Valley Encephalitis Outbreaks: 

Yakima Valley Encephalitis Outbreaks 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)

Slide6: 

Spokane San Juan Island Pierce King Snohomish Skagit Whatcom Clallam Jefferson Grays Harbor Thurston Kitsap Clark Cowlitz Lewis Skamania Wahkiakum Mason Yakima 7 Cases ( 6 WEE, 1 SLE) Chelan Okanogan Ferry Stevens Pend Oreille Lincoln Kittitas Whitman Klickitat Benton Walla Walla Columbia Garfield Asotin Franklin Adams Grant Douglas Pacific Reported Human Cases of Mosquito-borne Disease (1970-1982) Western Equine Encephalitis St. Louis Encephalitis Total cases = 12

Slide7: 

Spokane San Juan Island Pierce King Snohomish Skagit Whatcom Clallam Jefferson Grays Harbor 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 Adams Grant Douglas Pacific Western Equine Encephalitis Horse Cases (1953-1983) Suspect cases Confirmed cases

West Nile VirusIn the United States: 

West Nile Virus In the United States

WNV Background: 

WNV 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”

West Nile Outbreaks: 

West Nile Outbreaks Israel 1951-1954, 1957, 2000-2002 France 1962, 2000 South Africa 1974 Romania 1996-1997 Italy 1997 Czech Republic 1998 Republic of the Congo 1998 Russia 1999 United States 1999-2002

Outbreak Timeline: 

Outbreak 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

West Nile Virus Transmission Cycle: 

Incidental infections Bird reservoir hosts Incidental infections West Nile Virus Transmission Cycle Mosquito vector

WNV in the US Speculated Pathways of Introduction: 

WNV in the US Speculated Pathways of Introduction Human-transported bird Legal Illegal Human-transported mosquitoes Storm-transported bird Intentional introduction (terrorist event)-not likely Infected human traveler-not likely

WNV Symptoms: 

The incubation period for West Nile Virus is generally 3-14 days following a bite from an infected mosquito. WNV Symptoms High Fever Headache and body aches Skin rash Swollen lymph glands Neck stiffness Disorientation Convulsions

Distribution of WNV Before 1999: 

States with WNV (0) Distribution of WNV Before 1999

Distribution of WNV as of November 1999: 

States with WNV (4) Distribution of WNV as of November 1999

Distribution of WNV as of November 2000: 

States with WNV (12 + DC) Distribution of WNV as of November 2000

Distribution of WNV as of November 2001: 

States with WNV (27 + DC) Distribution of WNV as of November 2001

Distribution of WNV as of November 2002: 

States with WNV (44 + DC) Distribution of WNV as of November 2002

Distribution by County October 7, 2002: 

Distribution by County October 7, 2002

Case Summary 1999-2002: 

Case Summary 1999-2002 As of December 31, 2002 **As of December 1, 2002

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

*As of Dec 19 WNV Case-Patient Demographics & Mortality United States, 1999-2002*

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

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

Protecting Public Health: 

Protecting Public Health Surveillance Personal Protection and Education Mosquito Control

WNV Surveillance: 

WNV Surveillance Dead birds (especially crows, jays, ravens and magpies) Mosquitoes Captive sentinels (e.g. chickens) Veterinary surveillance Human surveillance

WNV Mosquito Species in Washington: 

WNV Mosquito Species in Washington Aedes cinereus Aedes vexans Culex pipiens Culex restuans Culex tarsalis Anopheles punctipennis Coquilletidia perturbans Ochlerotatus canadensis Ochlerotatus japonicus Counties (39) 22 27 28 1 35 26 10 5 1

Estimated Sensitivity of WNV Surveillance Methods: 

Human cases Veterinary cases Mosquitoes Dead birds Time Disease Activity Sentinel hosts Estimated Sensitivity of WNV Surveillance Methods

Personal Protection: 

Personal 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

Habitat Reduction: 

Habitat 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

Want More?: 

Want More? www.doh.wa.gov www.cdc.gov www.cfe.cornell.edu/erap/WNV/ Your local health department