Rainandheat provide breeding ground for mosquitoes

Jul. 15—With so many blood-sucking insects about to buzz, what is the risk of mosquito-borne diseases?

"We've been monitoring mosquitoes in the state for over 20 years and our wetter warmer years are bad years for mosquitoes overall," said Phillip Armstrong a mosquito entomologist at the Connecticut Agriculture Experiment Station. "With the rainfall we've been having now and the hot weather coming up, those are the perfect conditions for a large numbers of mosquitoes."

But whether that weather means more mosquito-borne disease is more complicated. While mosquito population booms can synchronize in large areas, not all species react to weather the same way. Culex pipiens, also knows as the "house mosquito" for example, thrives in urban areas and can carry West Nile Virus. But it's normal breeding grounds might be flushed out in storm events.

"When you get a major flooding event they get washed out," said Armstrong, explaining that they love breeding in storm drains. "So too much rain is bad for some species, but there are some exceptions to that, so it's hard to say how it'll play out."

There are 54 species of mosquitoes in Connecticut according to the Connecticut Mosquito Management Program. Roughly less than half of these species feed on humans or livestock, which means they can transmit disease. Over a dozen species can transmit West Nile according to a report published by the Connecticut Agricultural Experimentation Station.

And recently the U.S. Centers for Disease Control and Prevention issued a health alert for locally-acquired malaria in Florida and Texas. This is the first time such a warning has been issued in this country over the past 20 years.

"Malaria is a parasitic infection," said Dr. Asha Shah, director of infectious diseases at Stamford Hospital. "Malaria is spread by vector. A mosquito will contract malaria from a person when it bites a person with malaria."

Locally-acquired malaria means that a mosquito had to have picked up malaria parasites from a human who was infected, and then bite someone else, Shah said. The disease did not come from a mosquito bite abroad. That's worrying because the malaria-carrying mosquito genus, Anopheles still lives all over the U.S., including Connecticut, she said.

"After COVID nobody was travelling," said Dr. Shah. "But this year they're travelling everywhere ... I think this contributes to some of this because someone can unknowingly contract malaria and it comes back with them to the United States to get transmitted to someone else."

It can sometimes take weeks before symptoms of malaria erupt, medical experts say.

Dr. Shah advises that anyone who has been travelling to take symptoms of unusual fever seriously and see a doctor. She also recommends that anyone experiencing periodic fever who hasn't been travelling to also seek medical help.

"If someone has an unexplained fever without a known cause and you can't figure it out — maybe that's locally acquired malaria," she said

Dr. Shah said there are treatments for malaria, which can be fatal in severe cases. It's best to seek treatment if you think you're infected, she said.

With climate change, malaria and other mosquito-borne diseases are likely to have an easier time moving through Connecticut, scientists say. It's not just that the state is becoming warmer. Globally, places where malaria already occurs are becoming warmer too, allowing mosquitoes to thrive and move.

"Global climate change can affect areas where there is malaria and spread it to other areas where maybe there isn't malaria, or expanding the area where it's more prevalent," said Dr. Shah. "Then people go travelling ... and it's kind of this vicious cycle."

While it's unlikely that malaria will become endemic locally in the near future, that doesn't mean people shouldn't be cautious of mosquitoes, Armstrong explained.

"Globalization, climate change and poverty are the trifecta," said Armstrong. "They are the major factors that lead to increased risk of these diseases."

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Armstrong recommends residents dump any standing water in buckets or containers near their homes, use mosquito repellant while outside, and make sure your window screens are in good repair.

"The measure of last defense is going after the adults and spraying chemical insecticides in the event of an outbreak," said Armstrong. "But in general the first line is what we can do individually, covering up, wearing repellant and limiting time outdoors when mosquitoes are most active."

Connecticut used to have it a lot worse with respect to mosquito-borne diseases. Armstrong explained that the American Anopheles mosquitoes carried malaria as far north as Boston.

"Thus, we see since the early settlement of the State, there is scarcely a year in which there are not a few sporadic cases," wrote Dr. C.W. Chamberlain, secretary of the state board of health for Connecticut in an 1881 report.

It was actually one of the founding imperatives of the CDC to eliminate malaria as a public health risk in the United States back in 1946, and the primary reason the agency is based in Atlanta, Ga., as the South was the epicenter of malaria transmission.