Standing water can attract mosquitoes and residents should make sure there is none around their homes. That means making sure trash cans aren't filled with rain water, checking for clogged gutters and fixing leaky faucets.
"A little frisbee turned upside down with a half inch of water is a breeding ground," said Peter Beilenson, Howard County's health officer.
Beilenson said these methods are better than spraying. It's impossible to spray every area in the state, he said. And spraying doesn't get every mosquito as it falls to the ground, he added.
People should watch for symptoms of the disease.
"If you have been bitten by a mosquito and have severe symptoms you should see your health care provider," Beilenson said.
The state has released few details about the 21 cases of West Nile this year. Eight of the incidents were people who lived in the Baltimore region, seven on the Eastern Shore, five in the Washington suburbs and one in Western Maryland.
There is no specific treatment for West Nile. Milder symptoms such as fever and aches will pass on their own. People with more severe cases usually have to go to the hospital for supportive treatment such as help with breathing and to get intravenous fluids.
State officials expect more cases before mosquito season ends this fall. It takes three to 14 days for symptoms to develop, so there might be a delay in reporting.
"We expect to see more, but I can't say how much more," Feldman said. "Do I expect to see one or two more, or 10 or 20? I can't say."
West Nile Virus this year
U.S. confirmed cases: 1,993
U.S. confirmed deaths: 87
Maryland confirmed cases: 21
Maryland confirmed deaths: 1
Source: Centers for Disease Control, Maryland Department of Health and Mental Hygiene
Tips for preventing West Nile Virus
•Avoid areas of high mosquito activity.
•Avoid unnecessary outdoor activities at dawn and dusk when mosquitoes are most active.
•Wear long pants, long-sleeved shirts and hats when concerned about mosquito exposure.
•Use an EPA-registered insect repellent.
•Clean rain gutters to allow water to flow freely.
•Remove old tires or drill drainage holes in tires used as playground equipment.
•Turn over wading pools, wheelbarrows, wagons and carts when not in use. Flush water from bottom of plant holders twice a week.
•Replace water in birdbaths at least twice a week.
•Turn garbage can lids upside down and make sure trash receptacles are empty of water.
•Fix dripping faucets.
•Aerate ornamental pools and water gardens or stock with fish and use a circulating filter system.
Source: Maryland Department of Health and Mental Hygiene
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