Seeing Mosquitoes Everywhere? It’s Not Your Imagination

If it feels like mosquitoes are everywhere right now, it’s not your imagination. But experts say the species thriving in recent rains aren’t known for carrying the West Nile virus.

Dr. Michael Merchant, an entomologist with the Texas A&M AgriLife Extension, says the mosquitoes most people are seeing are floodwater mosquitoes.

“They’re very aggressive and they have a pretty painful bite as far as mosquitoes go,” explained Merchant. “They’re the ones that come out after really heavy rains because they lay their eggs in low spots in the ground.”

The mosquitoes can spread heartworm disease to dogs, but don’t transmit the West Nile virus.

The aedes and culex types of mosquitoes that spread West Nile prefer stagnant water. Merchant says their breeding grounds are disrupted by fresh, heavy rains at a time when cooler temperatures signal a slowdown in activity.

“The West Nile virus mosquitoes do not like this kind of weather. It washes out their dirty stinky breeding holes and causes them to go away a little while,” said Merchant.

Even so, he says people shouldn’t let their guard down.

Last week, Plano reported a second human case of West Nile virus and announced plans for targeted mosquito spraying Monday night.

Dallas County’s Health Department says the typical mosquito-borne season is from April through November. The health department expects to see additional West Nile virus activity this fall as recent rains will provide extra water sources for future breeding.

The department recommends people drain standing water in their yards and continue to take West Nile precautions. They include using repellent with DEET, wearing long sleeves and pants outside and avoiding the outdoors at dusk and dawn when mosquitoes are more active.

Merchant points out the mosquitoes that carry Zika and Denge remain active. But, locally transmitted cases have not been reported.

Texas reports three Zika cases so far in 2018 and all were transmitted during travel outside the U.S.

Dallas County’s Health Department says the risk extends to travelers. The departments warns travelers who return from regions of the globe where Zika exists use an EPA approved mosquito repellent for 3 weeks after returning to the U.S. to avoid infecting local mosquitoes.

Methodist Health System Infectious Disease Physician Dr. Shantala Samart says West Nile is the primary concern. Although human cases haven’t reached high levels this year, she asks patients to take precautions no matter what the mosquito conditions.

“This year so far we’ve been somewhat lucky compared to prior years and hopefully that trend continues,” said Samart. “With these new rains, we’ll have to wait and see.”

“The majority of patients who are bitten by a mosquito that’s carrying West Nile will have a mild viral illness,” Samart added. “It’s the small proportion of patients, usually those who are older and who have underlying medical illnesses, who develop the more aggressive disease which is the West Nile neuroinvasive disease. That’s the one we worry about.”

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