Warmer weather means graduation parties, pool time, and summer fun in the sun. It also means mosquito season is here. Time to prepare and take precautions.
The Prince William County Department of Public Works recently announced that it has confirmed the area’s first positive sample of West Nile virus found in a collection of mosquitoes on May 18.
The virus was detected in a mosquito sample taken in Woodbridge, according to a press release. The location “[i]s not a new area. In the past, West Nile virus has been active throughout Prince William County, but we see our most consistent activity along the I-95 corridor,” said Nathaniel Nagle, environmental program manager for Prince William County Department of Public Works.
“Mosquitoes testing positive for West Nile virus is a relatively common occurrence that happens every year [in the county]. We can see as few as 10 positive mosquito pools in a low year and as many as 200+ positive mosquito pools in the most active years,” Nagle said.
Nagle explained that the virus was detected in a pool of Culex pipiens-restuans mosquitoes – two similar, but different mosquito species known to carry West Nile Virus. Culex pipiens is native to Africa but is now widely found around the world. Culex restuans is more common is the eastern and central portions of North America and can be found from Canada to Mexico.
West Nile virus is the leading cause of mosquito-borne disease in the continental United States and is most commonly spread to people by the bite of an infected mosquito, according to the Centers for Disease Control and Prevention.
Most people infected with the virus will not develop symptoms, but about 20% will “develop a fever with other symptoms such as headache, body aches, joint pains, vomiting, diarrhea, or rash,” and very rarely the virus can be fatal.
The CDC website reports two cases of West Nile virus disease in humans in Virginia as of May 25. The county press release did not indicate any human cases of West Nile virus present in Prince William County at this time.
The county’s Mosquito and Forest Pest Management Branch’s mission is to reduce populations of mosquitoes and monitor West Nile virus activity throughout the county. To achieve this goal, the branch engages in a multi-faceted approach to detect and prevent human transmission of the virus.
Field technicians check thousands of areas of standing water throughout the county to determine whether mosquito larvae are present. Technicians kill mosquito larvae by applying a larvicide, which is an EPA-approved microbial insecticide.
Technicians also use a variety of traps to capture adult mosquitoes at defined areas in the county. Once trapped, adult mosquitoes are counted, identified and tested for West Nile virus. Homing in on areas of known virus activity helps the county concentrate control efforts on affected areas.
If adult mosquito populations are great or there is a high concentration of West Nile virus activity in the area, the county deploys chemicals to control the adult mosquitoes known as “adulticide.”
“We typically spray an approximate half-mile radius around the trap site that collected the positive mosquitoes. We perform ultra-low volume (ULV) spraying using a truck-mounted sprayer at a rate of 1 fluid ounce per acre,” Nagle said.
The Department of Public Works applied insecticide targeting adult mosquitoes at the identified site in Woodbridge on June 1 and will continue to monitor the area throughout mosquito season.
Educating residents on mosquito control is also part of the Mosquito and Forest Pest Management Branch’s mission.
“We perform outreach through the County’s social media accounts, at in-person events like farmers markets, and through publications. We schedule door-to-door outreach in targeted neighborhoods where we determine there is a higher than normal mosquito population or heavy virus activity,” said Nagle.
The county encourages residents to help control the mosquito population. “Residents can reduce mosquitoes around the home by eliminating objects that can hold water such as flowerpot rims, tarps, tires, children’s toys, gutters, etc.,” Nagle said, adding: “Residents can also protect themselves and their families by using an EPA-registered insect repellent and wearing long-sleeved shirts and pants.”
Residents may also contact staff at the PWC Mosquito and Forest Pest Management Branch at 703-792-6279 or firstname.lastname@example.org with questions or for more information on mosquito control.
Reach Cher Muzyk at email@example.com