By Derrick Perkins

City scientists detected West Nile Virus in area mosquitoes last month, but say it’s a regular occurrence and not at a level they find concerning.

Those tasked with keeping tabs on the local mosquito population found signs of West Nile Virus on July 8. First spotted in the U.S. in 1999, the virus has since spread across the country and Canada, according to the Centers for Disease Control and Prevention.

In Alexandria, officials have found mosquitoes positive for West Nile Virus for years. Like clockwork, mosquitoes carrying the virus are identified beginning in July or early August, said Daniel Sherwood, a biologist with the city’s environmental health division.

“West Nile is endemic to the area, meaning that we do see it on an annual returning basis. That has been recognized for some time now,” he said. “We’ve been monitoring it for over 10 years now and have identified it every year. We anticipate continuing to identify it.”

In the early days, health officials tested birds for the presence of the virus. Since most local birds carry West Nile — and they do not transmit it to humans — scientists have since begun tracking its presence in the mosquito population.

After leaving traps out for 24 hours, officials collect captured mosquitoes, separate them by genus and species and test for West Nile. Then, using statistical analysis tools, scientists get a rough idea of the virus’ prevalence locally.

They also have an idea of when West Nile will peak and when it will taper off, Sherwood said. After being detected, the virus usually is most prevalent in September and almost completely gone by late October.

Sherwood said the virus’ trajectory this year has not reached a level where scientists would begin taking any action other than informing the community of its presence and urging residents to take basic precautions.

“We’re continuing to monitor and, as the season progresses, we will keep the city informed of any new developments,” he said.

While West Nile can lead to meningitis, inflammation of the brain or febrile illness, the CDC estimates 70 to 80 percent of people infected will not show any signs of the virus. About one in five will suffer symptoms like a fever, vomiting, diarrhea, rash, headaches, body aches and/or joint pain. Most recover, though feelings of fatigue and weakness can last for weeks and even months.

A small group of people — less than 1 percent of those infected — will suffer from one of the aforementioned neurological illnesses. Of them, about 10 percent will die, according to the CDC.

Though there are no treatments or vaccines for West Nile, national health experts recommend over-the-counter medications for the virus’ milder symptoms. Those suffering from a more serious case likely will need hospital care, according to the CDC.

Given the lack of available treatments, officials at the local and national level suggest precautions such as using bug spray, wearing long-sleeved shirts and pants, and eliminating sources of standing water, like flower pots or gutters.

“The real big thing is always empty any standing water around your house,” Sherwood said. “That’s kind of the must-have in there. You get rid of the source of mosquitoes and you get rid of the problem.”