BALTIMORE, MD—The Maryland Department of Health on Thursday announced that an adult living in the Baltimore Metropolitan area has tested positive for the West Nile virus – the first confirmed human case of the virus in Maryland this year.

The West Nile virus is transmitted to humans by mosquitoes who have been infected by feeding on birds that have the virus. In rare instances, the virus may be spread from person to person through organ donation, blood transfusion, breastfeeding, or from pregnant mother to fetus.

The disease affects the nervous system, and up to 80% of people who are infected will not display any signs of illness at all. Those who have underlying health conditions, however, could become seriously ill.

“We are in the season when we start to see West Nile virus spread in Maryland,” said MDH Deputy Secretary for Public Health Services Dr. Jinline Chan. “We urge people to be vigilant and take steps to avoid infection. Disease surveillance teams are closely monitoring for any signs of increased numbers of infected mosquitoes that may turn up in areas across the state.”

West Nile virus was detected in the United States for the first time in 1999, and the number of Marylanders infected with the virus fluctuates each season. In 2019, there were seven people who were confirmed positive in the state, one in 2020, and in 2021 two people in Maryland were known to have contracted the virus.

While most people do not develop symptoms from this virus, some people who develop illness may experience mild symptoms such as fever, headache, and body aches; occasionally, a skin rash and swollen lymph glands may be noticed. These symptoms may last a few days or as long as several weeks. People who are older than 50 years or have immunocompromised conditions can become seriously ill.

People who are concerned about mosquitoes should cover up exposed skin and use an EPA-registered insect repellent according to package directions. Residents are also urged to monitor their own yards and gardens for areas of high mosquito activity, especially standing water that can serve as a breeding ground for mosquitoes. Small amounts of water in a discarded can or container will support dozens of mosquitoes, as will clogged rain gutters or drain pipes.

Although birds are not routinely tested for West Nile virus in Maryland, sick or injured birds can be reported to an appropriate local wildlife rehabilitator. Residents can call 1-877-463-6497 for a list of licensed rehabilitators or visit the Maryland Department of Natural Resources web site at DNR Wildlife pages.

For more information on West Nile virus, including data and educational materials, visit the MDH Center for Zoonotic and Vector-borne Diseases or the Centers for Disease Control and Prevention West Nile virus information page.

Photo by Jimmy Chan from Pexels