(Washington, DC) - District of Columbia Department of Health (DOH) Director Gregg A. Pane, MD announced today that two mosquito pools in the District tested positive for the West Nile Virus (WNV).
The first pool of mosquitoes consisted of 12 female Culex pipiens and was collected from the 4400 block of Harrison Street, N.W. on July 22. The second mosquito pool was collected from the 500 block of LaBaum Street, S.E. on the same day and consisted of 25 female Culex pipiens. The pools tested positive on August 5 and were confirmed to be positive in follow-up tests on August 8. The District of Columbia Public Health Laboratory conducts all mosquito pool testing by using the Real-Time Polymerase Chain Reaction (RT-PCR) method.
In response to the positive test results, DOH staff larvicided and distributed literature at the locations and the surrounding eight-block areas, as well as at other locations throughout the District, said Dr. Pane. We are at the height of West Nile virus season. As part of our 2005 West Nile Virus and Arbovirus Surveillance Plan, we are continuing our efforts to conduct surveillance and to control the mosquito population.
In 2005, DOH has larvicided 3136 catch basins throughout the District and collected and tested, in conjunction with the US Army, 402 mosquito pools, consisting of 4,956 individual mosquitoes. DOH conducts mosquito surveillance and mosquito control in partnership with the US Army. Traps are set in all wards of the District in a grid pattern to serve all areas of the District.
Residents are asked to guard themselves against mosquito bites. Everyone must fight the bite and keep in mind that protection and prevention are the keys to reducing human risk. To reduce risk, thoroughly rid areas of standing water to eliminate areas where mosquitoes can breed, avoid mosquito bites by wearing long-sleeved shirts and long pants and apply approved insect repellant when outdoors, added Dr. Pane.
The DOH no longer collects and tests dead birds because WNV is considered endemic in the District. However, the department does track and record dead birds and requests that the public call the DOH WNV Call Center at (202) 535-2323 to file a report. If you find a dead bird, please dispose of the bird yourself. To properly dispose of the bird, please follow this procedure:
- Wear protective gloves or use a plastic bag as a glove
- Place or wrap the dead bird in a plastic bag and tie the bag securely
- Dispose of the bag in an outdoor trash receptacle
- Wash your hands with soap and water
Remember, the WNV is not transmitted directly from birds to humans. To date in 2005, there have been no human cases of WNV in the District. Last year forty-two (42) mosquito pools and two (2) humans tested positive for WNV in the District.
DOH, in cooperation with other District agencies, is asking residents and businesses to help reduce the risk of the WNV by eliminating mosquito-breeding sites around their homes and businesses. WNV is mainly an infection of birds, but on rare occasions an infected mosquito may spread it to a human. In human infections, the virus generally causes no symptoms, or may cause mild flu-like symptoms and is rarely severe. Several types of mosquitoes thrive in the District and surrounding areas including the Northern house mosquito (Culex pipiens), which bites from early evening to dawn. The Culex mosquito is known to transmit WNV, particularly to birds such as crows, blue jays, and hawks. The Asian tiger mosquito (Aedes albopictus), which bites both day and night, is also prevalent in the area.
The risk of acquiring WNV infection is low. Even in areas where transmission of WNV is known to be occurring, only a small proportion of mosquitoes are likely to be infected. Even if an infected mosquito bites a person, the chance of developing illness is low. DOH has initiated the application of larvicide to areas where Culex mosquitoes breed, especially in catch basins and small cavities where water can sit for several days. There are no current plans to spray with adulticides.
Senior citizens and those with suppressed immune symptoms are more vulnerable. These residents are encouraged to stay indoors when mosquitoes are active. If persons must be outdoors, they should wear long-sleeved shirts and long pants and apply insect repellent with DEET or other mosquito repellents to exposed skin according to manufacturers directions. For children, use a product with DEET concentration of less than 30%.
DOH encourages all residents and businesses to reduce mosquito-breeding areas on their respective properties. Several types of mosquitoes can breed in stagnant water; therefore it is important to correct any drainage problems. Other mosquito prevention tips include the following:
- Dispose of cans, bottles and open containers properly
- Store items for recycling in covered containers
- Remove discarded tires. Drill drainage holes in tires used on playground equipment
- Cover tires stored outside before each rain and uncover them promptly afterwards to prevent water from standing on the tarps
- Clean roof gutters and downspouts regularly
- Eliminate standing water from flat roofs
- Turn over plastic wading pools, wheelbarrows, and canoes when not in use
- Cover waste containers with tight-fitting lids; never allow lids or cans to accumulate water
- Flush bird baths and potted plant trays twice each week
- Adjust tarps over grills, firewood piles, boats or swimming pools to eliminate small pockets of water from standing several days
- Re-grade low areas where water stands; clean debris in ditches to eliminate standing water in low spots
- Maintain swimming pools, clean and chlorinate them as needed, aerate garden ponds and treat with mosquito dunks found at hardware stores
- Fix dripping water faucets outside and eliminate puddles from air conditioners
- Store pet food and water bowls inside when not in use
By following these tips, we will reduce the mosquito population and the associated disease risks in all District neighborhoods. We all must work together to effectively fight the bite, added Dr. Pane.
For more information about this topic, please visit http://doh.dc.gov, http://www.cdc.gov, or call the WNV Call Center at (202) 535-2323.