Campaigns slash West Nile cases

Health officials said yesterday that awareness campaigns that include telling residents how to eliminate breeding grounds for mosquitoes have been a major factor in reducing the number of West Nile virus cases.

“We’re hoping that just the fact that we put out brochures and press releases and fact sheets will make people … learn how to protect themselves,” said Kim Mitchell, an epidemiologist for the Maryland Department of Health and Mental Hygiene.

The emergence of the West Nile disease alarmed health scientists and spread fear of an epidemic when it emerged in the United States several years ago, infecting as many as 9,862 persons and killing 264 in 2003.

The number of human cases decreased in 2004 to 2,539, with 100 deaths. As of July 26, the number of human cases in the country this year was 109, with two reported deaths, according to the U.S. Geological Survey and the Centers for Disease Control and Prevention.

The number of mosquito-borne West Nile cases in the region has also decreased.

Maryland officials report no cases of infected humans or infected mosquitos, compared with 16 human and 31 mosquito cases in 2004. The state had 36 cases of human infection and 46 of mosquito infection in 2003.

Virginia has eight cases of mosquito infection this year, compared with last year’s numbers of two human cases and 432 mosquito cases. The state had 14 human and 431 mosquito infections in 2003. Arlington officials said yesterday infected mosquitoes have been found in two of the county’s mosquito traps for the first time this year, but no people or birds have tested positive for the virus. Mosquitoes in Fairfax County tested positive last month.

The District did not return calls about the numbers of cases. However, federal officials said the city has had no reported cases this year.

Among the most important advice offered to residents is to stay indoors during peak mosquito hours and to drain standing water from such backyard breeding grounds as baby pools, birdbaths and abandoned tires.

Most people bitten by infected mosquitoes do not get sick, but the virus can lead to fatal illnesses, particularly in people 50 and older.

Health officials have also attributed the low number of cases this year to a cool spring and the large amount of rain, which has flushed sewer systems, major breeding areas for mosquitoes.

“If it’s very cold, it takes a long time for a mosquito to be infected,” said David Gaines, a public health entomologist for the Virginia Department of Health. “If it’s hot, they become infected in a matter of two or three days.”

Another mosquito-borne disease, Eastern equine encephalitis, known as EEE, was also a significant health concern over the past few years, but now is much less prevalent than the West Nile virus. For example, the first case in Virginia was reported in 1975. However, there have been five cases since then, with the last being in 2003. There are no such cases right now in either Maryland or Virginia.

Ned Hayes, a medical epidemiologist for the CDC, said so many factors contribute to the West Nile problem, including humidity, rainfall and community response, that it is “impossible to predict which years will be the worst.”

He pointed out the number of cases has increased in Western states, which means West Nile continues to be a major health concern. “The situation hasn’t improved,” he said. “It continues to be a health problem across the U.S. It’s still important for people to recognize the risk is there.”

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