West Nile Virus Information for Whatcom County
West Nile virus is a bird disease spread by mosquitoes, which sometimes affects humans and certain animals, such as horses. Since 1999, when the West Nile Virus (WNV) was first documented in New York, it has steadily moved westward across the country. It reached Whatcom County in the fall of 2002 when test results from a symptomatic horse in rural Whatcom County confirmed positive for WNV. Since that time, there have been few human cases of WNV in our state. There has been a single human case of WNV in Whatcom County, in 2009, but the virus was acquired in Yakima County. So far, there have been no human cases that acquired the virus in Whatcom County. It is important to know that not all mosquitoes will carry the virus, and only a few of the 20+ different species of mosquitoes found in the state are competent vectors of the disease. Most people who do become infected with the virus will not have any type of illness.
What is the health risk from the West Nile Virus?
Although the chances of a person getting WNV are small, all residents in areas where the virus is active are at risk. Only about 1 in 5 people who become infected will develop WNV symptoms, usually 3 to 14 days after exposure. However, persons over 50 years of age and/or with immune system deficiency are more at risk for getting symptoms than children or pets. Mild symptoms may include fever, headache and body aches, occasionally with a skin rash on the trunk of the body and swollen lymph glands. Chances of developing severe symptoms are about 1 in 150 cases. The symptoms of a severe infection include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. In 2005, 3,000 cases of the illness were reported across the United States, and of these cases, 119 involved fatalities. Though the number of fatalities is low compared to the number of reported cases of WNV, precautions should be taken to reduce your risk.
Residents can help reduce risk from the WNV
There are some simple steps you can take to reduce your risk. The best way to minimize the threat of WNV is to control mosquito populations and prevent exposure to mosquitoes. To help control the mosquito population, decrease mosquito habitat by emptying old tires, buckets, plastic covers, toys and other containers around your home where water can accumulate and serve as a breeding ground for mosquitoes. Change water in birdbaths, fountains, wading pools and animal troughs weekly. To protect yourself from mosquito bites, wear loose fitting, long sleeved shirts, long pants and other protective clothing when in mosquito-infested areas. You may also consider using a mosquito repellant.
For more information on preventing mosquito bites, visit the following WSU link:
West Nile Virus - Guidelines for Preventing Mosquito Bites
Why should I worry about old tires and birdbaths, when there is a wetland in my neighborhood?
One type of mosquito, the Culex pipiens (AKA "the house mosquito"), is of most concern due to their efficiency of transmitting WNV when infected. Culex larvae grow in water filled containers found around most homes. Tires are a particular problem because they always hold water and the black color provides warmth. Any object that holds stagnant water, except a chlorinated pool, can produce thousands of mosquitoes. Healthy wetlands provide minimal habitat for mosquitoes, because there are native fish, frogs, toads, newts, salamanders and other predators of mosquitoes. For more information on reducing mosquitoes at home, visit the following WSU link:
Guidelines for Reducing Mosquitoes at Home
Mosquito surveillance efforts of the Whatcom County Health Department
Due to a relative lack of West Nile Virus activity in our county, the health department is no longer actively monitoring mosquito populations. Dead birds are still being tested in summer months when mosquitoes are active. In previous years, surveillance techniques were used to locate mosquito breeding sites and areas of severe adult mosquito activity. Mosquito collecting techniques included larvae dipping, and dry ice baited adult mosquito trapping. These efforts contributed to local, state and national databases by identifying the species of mosquitoes in Whatcom County and documented the presence or absence of virus in collected mosquitoes. There was no presence of the virus in all mosquitoes collected in Whatcom County for testing. The Whatcom County Health Department continues to work with other local agencies and businesses in the county. Dead bird monitoring is the primary means for assessing WNV activity in Whatcom County and dead birds may be reported using the Washington State Department of Health's Dead Bird Report form online. For additional Whatcom County West Nile virus information, visit Cooperative Extension's West Nile virus home page.
If I see a dead bird, what should I do?
It has been shown that the best indicator of West Nile Virus in a community is a die off of certain birds, particularly crows, jays, ravens, magpies and raptors. Although most birds can be a reservoir of the virus, these birds are most affected by the disease. WNV is not transmitted directly from the dead bird to humans, but caution and proper personal protection should be used if handling a dead bird. We are interested in collecting information about dead birds as part of our surveillance efforts to identify the presence of WNV in Whatcom County.
If you find one or more dead bird(s) in Whatcom County:
If the bird is not needed for testing you can dispose of the bird in the trash. When handling any dead bird, use gloves and wash your hands when finished.
What is being done about Mosquito Control?
While the Health Department has no specific authority to control mosquitoes, we will encourage public and private landowners to evaluate their mosquito situation. If there has been a history of mosquito problems in certain areas, landowners in that area may need to take steps to control mosquito larva. State permits are required to apply pesticides to water. Therefore, some advanced preparation is needed before pesticides can be applied. A streamlined permitting process has been established by the Washington State Department of Ecology and can be found with additional at the following link:
Washington Department of Ecology - Aquatic Mosquito Control General Permit
For more information about WNV visit the following links:
CDC - West Nile Virus Questions and Answers
Washington State Department of Health - West Nile Virus in Washington