In this issue:
WEST NILE VIRUS IN ROCK CREEK NATIONAL PARK
West Nile Virus is a mosquito-borne virus first discovered in Africa in 1937. We don't know how the virus arrived in the United States, first detected in the New York City area in 1999. Since then, the virus has spread into the northeast, the Midwest, and the southeast. The virus was found in dead birds and a few mosquitoes in late 2001 in the Washington, D.C. area; and numerous dead birds, virus-carrying mosquitoes, and human cases have been found in the metro area in 2002.
Rock Creek Park as a whole does not provide much natural habitat for mosquitoes since very little standing/stagnant water is present. Mosquitoes do not lay eggs in moving water, so the creek and its tributaries are not sources of mosquitoes. The small vernal (seasonal) pools that exist in the floodplain do provide habitat for mosquitoes, but they are normally dry during the peak of mosquito season in late August and early September. However, Rock Creek Park does have manmade, artificial habitats. Buildings such as the Maintenance Yard and the horse stables provide potential habitat in rain gutters, spare tires, buckets, trashcans, and tarps, and virus-carrying mosquitoes have been found in these areas.
The Rock Creek Park staff checks the areas around all buildings and visitor use areas on a weekly basis. Mosquito traps are set in visitor use areas, and the catches are submitted for testing. Artificial habitats are eliminated and/or repaired so that water drains. Where the water cannot be removed, a biological control (that can be purchased from local garden centers) that is specific to mosquito larvae is applied, thus killing the larvae before they can emerge as adults. Storm water catch basins are treated using this method.
The elimination of mosquito habitat is the number one way to control mosquito populations. Removing standing water in yards that has collected in plastic wading pools, wheelbarrows, potted plant saucers, tarps, etc., is a must. Garbage cans should be covered with the lids facing down. Roof gutters should be free of leaves, allowing water to drain. Water in birdbaths should be changed once per week. Pet food and water dishes should be stored inside when not in use. Dripping spigots should be repaired, and drain puddles under air conditioners should be eliminated. Swimming pools should be cleaned and chlorinated. Garden ponds should be aerated. If citizens follow these simple steps, they can significantly reduce mosquito numbers in their neighborhoods.
To protect from bites, wear long-sleeved shirts and long pants outdoors. Stay inside at dawn and dusk when most mosquitoes are active. There are many mosquito repellents on the market. The most effective repellents contain the active ingredient DEET. Be sure to read the label closely before applying the repellent. Products should contain no more than 35 percent DEET for adults and less than 10 percent for children.
The presence of West Nile Virus should not keep you from
enjoying the outdoors during the warm weather. Taking precautions to avoid
bites and infested areas should greatly reduce the risk of contacting
the virus. The Center for Disease Control has a good web site (http://www.cdc.gov)
for more information on West Nile Virus. Most state and county health
departments also have web sites addressing West Nile Virus and what they
are doing to control it.
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