Despite the cooling temperature, the mosquitoes could still bite.
Richard Duhrkopf, associate professor and chair of the Institutional Animal Care and Use Committee at Baylor, said the number of positive West Nile virus cases will decrease over time because some mosquitoes will die off due to cooler temperatures. However, the West Nile virus will continue to spread because not all mosquitoes will die from the cooler temperatures.
“Because their development is closely tied to the temperature, there will be very few once it gets cold,” Duhrkopf said. “It will persist in the winter because some mosquitos can reproduce better in this weather.”
According to the Center-for Disease Control and Prevention, West Nile virus is a seasonal epidemic that flares up during the summer and continues into the fall. The virus is commonly spread by mosquitoes that feed on infected birds. The infected mosquitoes then spread the disease to humans when they feed on their blood.
“There will be infected birds during the winter,” Duhrkopf said. “There will be mosquitoes circulating the virus from bird to bird throughout the winter. Those that feed off birds prefer colder temperatures.”
Duhrkopf said while most of mosquitoes in the area will die off due to the cooling temperatures, others will take action to prevent being killed by the cold.
“Different mosquitoes do different things,” he said. “Some will seek a shelter. Others will lay eggs that will pass through the winter.”
According to the CDC West Nile virus website, 1,634 positive cases of the virus have been reported this year in Texas. Of those cases, the CDC has reported that 41 cases of West Nile virus have occurred in McLennan County. Kelly Craine, the spokeswoman for the Waco-McLennan County Public Health Department, said the facility has not received word of any new cases of West Nile virus.
“Well, we haven’t had any new cases since October 2,” she said. “We’re seeing less active cases. The cool weather is slowing them down but not killing them. It’s less mosquito activity, but they are still there.”
Despite the lack of new cases, Craine said the Waco-McLennan County Public Health Department continues to watch for any new positive cases of the virus.
“We’re always monitoring the West Nile virus number,” she said. “Our health authority, Dr. Farley Verner, is always looking for patients that are showing symptoms and that have the virus. We’re staying aware if they have symptoms or not.”
According to the CDC, one out of 150 people infected with the virus will develop severe illness, while up to 30 people who have the virus will experience milder symptoms. Approximately 80 percent, or four out of five, people infected with West Nile virus will be asymptomatic, or not experience any symptoms. For the 20 percent who are infected with West Nile virus, symptoms will develop between three and 14 days after a person is bitten by an infected mosquito.
Craine said people still need to be alert about the virus. “Be vigilant, be aware,” she said. “Anything could happen. It’s nature.”