The Salt Lake City Mosquito Control District plays an important public health role as climate change extends the season in which mosquitoes can infect people with dangerous viruses.
It’s midday in the Salt Lake City Mosquito Abatement District, and a colony of Sabethes cyaneus—also known as the paddle-legged beauty for its feathery limbs and iridescent coloring—is making its way to Ella Branham.
“They’re not very aggressive and they’re pretty picky eaters,” said Branham, a technician, as she exhaled into a glass tank to attract the insects with the carbon dioxide in her breath. “So I’ll feed her with my arm.”
Branham had volunteered to let the South American mosquitoes feed on their blood so they could produce eggs and maintain the colony for education and research at the Salt Lake City District Laboratory. It is one of many mosquito control areas across the United States trying to keep one of the world’s deadliest animals at bay – an animal that may be thriving as climate change favors a warmer, wetter environment.
Mosquitoes can transmit viruses such as dengue fever, yellow fever, chikungunya, and zika. They pose a particular threat to public health in Asia and Africa, but are also closely monitored in the United States. According to the US Centers for Disease Control, local authorities reported more than 1,100 cases of West Nile virus in 2022.
Most people who contract West Nile do not show any symptoms. However, some may develop vomiting, fever, and, rarely, seizures or meningitis. Over the past 25 years or so, nearly 3,000 deaths and more than 25,000 hospitalizations related to West Nile have been reported across the United States – most of them in August.
West Nile deaths have been reported this year in states including Texas and Colorado, and mosquitoes are believed to be the source of “locally acquired” malaria infections in people in Maryland, Florida and Texas.
Ary Faraji, an entomologist and executive director of the Salt Lake City Mosquito Control District, said monitoring shows mosquito season is starting earlier and lasting longer as the climate has warmed. The district used to be closed in mid-September every year, but this has become later and later. Last year, county workers were busy setting and checking traps until Thanksgiving.
And this year — in which an unusually snowy winter and a very rainy spring left more water in the landscape for mosquitoes to breed — his staff estimated that there were five times as many mosquitoes in May as the average year.
This is where the health risk comes into play. While both males and females feed on sugar or nectar throughout their lives, females require blood meals to nourish and develop their eggs.
“They are the real vixens,” said Faraji. “Some can be so beautiful and yet some can be so deadly.”
Faraji’s staff – made up of scientists as well as undergraduate and graduate students – catch, sort and test mosquitoes for viruses using drones, boats and all-terrain vehicles. Their work considers how trends ranging from weather patterns to population growth affect disease transmission.
“The more people you put in close proximity to the mosquitoes, the higher the chance of pathogen transmission,” he said, citing the challenges of the wetlands surrounding Utah’s Great Salt Lake.
Although dangerous, mosquitoes are also crucial to ecosystems around the world, with several species serving as pollinators or food sources for fish, birds, and frogs.
“We are trying to maintain a balance and suppress them to the point where they no longer negatively impact communities,” Faraji said. “Taking them away would definitely have a negative impact on our entire ecosystem.”
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