PHOTO: SHUTTERSTOCK

Mosquitos testing positive for West Nile Virus have been found in several Pittsburgh neighborhoods, and health department officials are urging people to be cautious around the insects this summer.

“Generally, the species of mosquitoes that carry West Nile Virus are active from dusk to dawn,” said Allegheny County Health Department Vector Control Specialist Nicholas Baldauf in a statement. “Residents can deter mosquito bites by using insect repellent on exposed skin or choosing to wear long sleeves and pants. Both methods are effective at reducing or eliminating the possibility of getting a mosquito bite.”

Mosquito samples collected in Brighton Heights, California-Kirkbride, Elliott, Sheraden, Esplen, and Marshall-Shadeland tested positive for West Nile Virus earlier in the month, and the health department sprayed areas with a low-risk insecticide to lower the mosquito population. The same is planned this week for Highland Park, Homewood, Point Breeze and Wilkinsburg, where samples also tested positive.

West Nile Virus is the leading mosquito-borne disease in the United States; it’s caused when an infected mosquito bites a human. According to the health department, most people infected with West Nile Virus do not feel sick. Common symptoms include fever, headache, body aches, joint pains, vomiting, diarrhea or a rash, but only 1 in 5 people infected with the virus develop symptoms. Less than 1 percent of infected people develop a serious illness.

The last reported human case of West Nile Virus occurred in September 2023, however, Dr. Ernesto Marques, an associate professor in the University of Pittsburgh School of Public Health’s Department of Infectious Disease and Microbiology, cautions that West Nile cases are likely underreported. 

“Diagnosing WNF [West Nile Fever] is often missed,” Marques said in an email. “A large fraction of cases is mild and can go unnoticed by the patient, and the symptoms are common with other more frequent diseases.” 

Marques notes the risk of neurological complications increases with age. People aged 50 and older are 10 times more likely to experience them, and people aged 80 and older are 43 times more likely. 

“The neurological symptoms can be confused with other diseases, like Parkinson’s disease and Guillain-Barré syndrome,” Marques says, therefore the number of West Nile Virus-related complications may be underestimated.

There is no vaccine for West Nile Virus, only treatment focused on alleviating symptoms. For neurological complications, hospitalization and close monitoring are required, he says.

Marques notes mosquitos breed in stagnant water, such as in plant vases, plastic containers, and water reservoirs, either inside or outside. He too recommends using mosquito repellents and reducing areas of exposed skin.

The health department noted mosquitoes can breed in as little as a half inch of stagnant water.

“Residents should pay close attention to potential breeding sites like stagnant water in tires, unused swimming pools, buckets, corrugated piping, and clogged gutters,” the statement said.