Epidemiologist who specializes in animal-related diseases at Colorado

One again state health officials have confirmed the first two human cases of West Nile virus for the 2008 season. The cases were reported from Boulder and Logan counties. Both patients are recovering from their illnesses.

According to John Pape, an epidemiologist who specializes in animal-related diseases at the Colorado Department of Public Health and Environment, “West Nile virus can be avoided by eliminating mosquito breeding grounds in back yards, wearing insect repellent and using other methods to avoid mosquito bites when outdoors.”

The cooperative surveillance conducted by state and local health departments, started on June 1, has shown Culex mosquito populations are still low but increasing. Historically, populations of Culex mosquitoes, which transmit West Nile virus, start to rapidly increase in July as temperatures begin to rise. Each season, this virus will be present and circulating around the state. The severity of the season will depend on the weather.

Last year, Colorado reported 576 cases with 7 deaths. Ninety-nine cases, or 17 percent, had meningitis or encephalitis, indicating the virus had entered the central nervous system. In reviewing statewide surveillance data from 2003 to 2006, Pape said patterns of human infections have emerged. “Approximately 85 percent of people who became ill with West Nile virus were infected when bitten by an infected mosquito during a six-week period from July 1 through the second week of August. Therefore, we are entering the peak season of West Nile virus transmission,” explained Pape.

Infected mosquitoes continue to feed through September and early October, depending on the weather, but fewer than 10 percent of human cases are contracted after Labor Day, Pape added. “July and August are the highest-risk months of being infected, and people should be extra diligent during this time and use whatever methods available to avoid mosquito bites. This is particularly important one hour before sunset through around midnight, when Culex mosquitoes are most actively feeding,” he said.

Pape said that individuals can reduce the number of mosquitoes by cleaning out gutters and other places around their homes where there are pools of standing water that are good breeding places for mosquitoes. Such breeding grounds include empty flowerpots, plastic swimming pools or old tires.

“If you have a birdbath, remember to change the water at least weekly. This also is a good time to repair torn window and door screens,” he said.

Additional precautions to take against West Nile virus include the following:

Use precautions or avoid outdoor activities, such as gardening at dawn and after dusk when mosquitoes are most active.
If outside at dawn or after dusk, cover up by wearing light, loose-fitting pants and long-sleeved shirts, shoes and socks.

Use approved mosquito repellents containing DEET, picaridin or oil of lemon eucalyptus. DEET products generally provide the longest protection. The other repellents work but must be applied more frequently. Follow the product label for correct use. Products with 10 percent or less DEET are recommended for children.

Prevention tips and additional information about West Nile virus is available online at www.FightTheBiteColorado.com. and the information via BerthoudRecorder.com