Number of South Dakota counties with West Nile detections reaches 50 The state Health Department today reported the number of counties with West Nile detections has reached 50. First detections of the virus were reported in Campbell and Corson counties, both in horses, and in a blue jay in Hutchinson County.
West Nile has now been reported in a total of 61 birds, 186 horses, and a sampling of mosquitoes from Brookings County. There have been three human cases, one each in Miner, Lyman and Potter counties. Nationally, there have been 453 human cases reported and 21 deaths.
Positive birds have been detected in the following counties: Beadle, Brookings, Brown, Brule, Charles Mix, Clay, Codington, Davison, Day, Grant, Hamlin, Hughes, Hutchinson, Lake, McCook, McPherson, Miner, Minnehaha, Moody, Roberts, Spink, Stanley, Sully, and Walworth.
Counties reporting WNV positive horses include: Beadle, Bennett, Bon Homme, Brookings, Brown, Butte, Charles Mix, Campbell, Clark, Clay, Codington, Corson, Day, Deuel, Dewey, Davison, Douglas, Faulk, Grant, Gregory, Haakon, Hamlin, Hand, Hanson, Harding, Hughes, Jackson, Jones, Kingsbury, Lake, Lincoln, Lyman, McCook, Marshall, Meade, Minnehaha, Pennington, Perkins, Roberts, Spink, Stanley, Sully, Turner, Union, Walworth, and Yankton.
West Nile is primarily a bird disease, and crows are especially susceptible. Mosquitoes become infected by feeding on an infected bird and can pass the virus to humans, horses or other hosts when they bite. Dr. Lon Kightlinger, State Epidemiologist for the Department of Health, said although most people who become infected do not become ill, the risk of human illness increases as the intensity of animal infection intensifies. Some may develop mild flu-like symptoms such as fever, headache, body aches, and occasionally swollen lymph glands or a rash. In rare cases West Nile may cause encephalitis, or inflammation of the brain. Individuals with severe or unusual headaches should seek medical care as soon as possible.
"The last reported human cases of mosquito-borne viral encephalitis in South Dakota were in 1988 (1 case) and 1984 (2 cases) of Western Equine Encephalitis. In the 1970s there were also human cases of St. Louis Encephalitis in the state. Since 1988 there have been no reported cases of mosquito-borne encephalitis in South Dakota," said Dr. Kightlinger.
The spread of WNV across South Dakota does increase the potential risk to humans. Dr. Kightlinger emphasized that the risk of West Nile is still low but encouraged people to take precautions to protect against mosquito bites:
* Get rid of old tires and other containers where water can accumulate and serve as a breeding ground for mosquitoes.
* Avoid outdoor activities at dusk and dawn when mosquitoes are most active.
* Wear long-sleeved shirts and long pants when in mosquito infested areas.
* Use mosquito repellents containing DEET, making sure to follow the directions on the container.
* Use bug lights and screen doors and windows.
* Communities in affected areas should consider adult mosquito control. On Aug. 29, the SDSU Cooperative Extension Service will offer another session of its mosquito control training for local officials. West Nile Virus Update: Mosquito Management in South Dakota is scheduled for 1-5 p.m. over the Dakota Digital Network and Extension's V-tel Network. Questions should be directed to the Extension Service at 688-4596.
South Dakota physicians are asked to be vigilant for patients who may be suffering from West Nile encephalitis. Human testing is available at the State Public Health Laboratory in Pierre.
Horse vaccination is recommended. Horse owners should see their veterinarians. Samples from horses suspected of infection with West Nile can be tested at SDSU's Animal Disease Research and Diagnostic Laboratory.
More information about West Nile can be found on the Department of Health Web site at www.state.sd.us/doh/West Nile/ and on the Animal Industry Board Web site at www.state.sd.us/aib/.