The West Nile virus is here and Colorado residents are being urged to take precautions.
The first two cases of West Nile this season were reported Friday by state health officials. The two patients, in Boulder and Logan counties, are recovering from the virus, officials said.
Culex mosquito populations are still low but increasing, officials warned. Populations of Culex mosquitoes, which transmit West Nile virus, rapidly increase this time of year as temperatures rise.
Within the next couple weeks, officials will have an idea of how severe or mild the West Nile season will be, said epidemiologist John Pape.
“Now is the time to take precautions,” he said.
Pape said 2007 was the second most active season for West Nile virus cases following the 2003 epidemic. Last year, Colorado reported 576 cases with 7 deaths. Ninety-nine cases, or 17 percent, had meningitis orencephalitis, 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,” said 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, he said.
“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.
Howard Pankratz: 303-954-1939 or hpankratz@denverpost.com
