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It’s summer, and with those longer days come backyard cookouts, outdoor activities and—ouch!—bug bites. Mosquitoes love Northern Virginia’s infamous hot and humid summers. And as the world’s deadliest animal, according to the Centers for Disease Control and Prevention, they’re more than just a nuisance at the family barbeque: They’re a health hazard.

But in partnership with Prince William County, ��������’s (BRL) is working to prevent outbreaks of mosquito-borne diseases.

Since 2016, in response to the Zika virus outbreak, the county and the university partner each year to collect mosquito samples and test them for diseases like West Nile virus.

“West Nile is endemic in the United States, and infections can be lethal,” explained , MS Biology ’15, PhD Biosciences ’19 , associate director of the BRL. Alem has led the mosquito testing program since 2019.

“Eighty percent of people will have no symptoms,” he said, “but about one in every 150 cases of West Nile is severe.” It’s a neuroinvasive disease, meaning severe cases can damage the nervous system, resulting in high mortality rates and a high likelihood of disability if survived. Even those with non-neuroinvasive West Nile virus, though most likely to make a full recovery, could experience symptoms for weeks or months.  

“We want to prevent the spread as much as possible,” Alem said.

Testing season starts in late spring and runs through the fall. Each week, samples are collected at more than 60 sites across Prince William County, and the mosquitoes are sorted by species. Vector species—meaning those that carry disease—are sent to the BRL for testing. Researchers extract RNA from the mosquitos and check for the markers of West Nile virus. They then send their report to county officials. If mosquitoes are positive for West Nile virus, the county will follow their larvicide and adulticide spraying protocols to eliminate the threat at the site where the mosquitoes were trapped.

“It allows us to more precisely target areas before they become a concern for the local community,” said Eli Hosen, environmental project manager for the mosquito and forest pest management branch of Prince William County Department of Public Works. “The lab provides us with a quick turnaround so we can respond as soon as possible.”

The program has been effective, Alem said, in reducing the number of West Nile carriers in the region. "Spraying is definitely working to control the spread."

Alem is in conversation with other counties in Northern Virginia to see if there’s interest in expanding the surveillance program. The BRL is also hoping to learn best practices on mosquito trapping from Prince William County to implement in other areas of research.

George Mason epidemiologist is looking into the possibility of a similar surveillance program in India for dengue fever, for example. And if deployed, researchers hope what they learn in India can be useful to their research here as well.

With almost 10 years’ worth of data from the ongoing testing, Alem is hoping the lab can one day look at trends in disease occurrence and correlating environmental factors.

“It's leading to new avenues of research for us,” said Alem.