The first human case of West Nile virus in 2019 has been reported in Philadelphia, health officials announced Tuesday.

West Nile activity in mosquitoes has also been reported in 57 of 67 Pennsylvania counties to date including all counties in the southeastern part of the state, the Philadelphia Department of Public Health stated.

The mosquito-borne disease, which can cause inflammation of the brain and lead to death in severe cases, is usually spread in summer and fall. There is no vaccine or medications to treat the illness.

This is the first reported case in Pennsylvania so far this year. New Jersey has one reported case in Hunterdon County, according to the U.S. Centers for Disease Control and Prevention.

Nationally, there have been 326 reported human cases of West Nile virus as of Sept. 4. People at greatest risk for serious infections from the virus are those who are over age 50 or immunocompromised. Symptoms include unexplained headaches, weakness, and fatigue, according to the CDC, though most people who become infected do not develop symptoms.

In 2017, only three cases of the virus were reported in humans in Philadelphia. In 2018, that figure rose to 17 cases, according to city health officials.

The best way to prevent the spread of West Nile virus is to control mosquitoes.

“We all have a role in preventing the spread of West Nile virus," said Thomas Farley, Philadelphia health commissioner. Farley suggested people wear mosquito repellent to help prevent bites.

Tips for mosquito-proofing your home and neighborhood include:

  • Anything that can hold water can breed mosquitoes, including flower pots, buckets, old tires, inflatable swimming pools, or even soda bottle caps. Check your property for these sources of standing water and dump them out.

  • Keep gutters clean.

  • Stock ornamental ponds with fish or aerate them.

  • Keep well-fitted screens on windows and doors.

To report mosquito problems in Philadelphia, contact the Public Health Department’s mosquito complaint hotline at 215-685-9000.