First Probable Human Case Of West Nile Virus Detected In Philadelphia

On September 17, Pennsylvania’s first probable human case of West Nile Virus infection in 2019 has been detected in a Philadelphia resident. Samples are being sent to the Centers for Disease Control and Prevention for confirmatory testing. 

The Departments of Health and Environmental Protection strongly recommend that all residents minimize their exposure to mosquitoes.

“While we encourage Pennsylvanians to enjoy the outdoors, we also want them to take proper precautions from mosquitoes while outside,” Secretary of Health Dr. Rachel Levine said. “With the first human case of West Nile Virus detected, we want people to protect themselves. Several simple steps can help protect yourself and loved ones from mosquito-related diseases.”

Although mosquitoes can bite at any time of the day or night, the mosquitoes that transmit WNV are most active at dawn and dusk. When outdoors, people can avoid mosquito bites by properly and consistently using DEET-containing insect repellants and covering exposed skin with lightweight clothing. 

To keep mosquitoes from entering a home, make sure window and door screens are in place and are in good condition.

The Department of Environmental Protection conducts regular surveillance and control to manage mosquito populations around the state. So far, DEP has detected WNV-infected mosquitoes in 32 counties.

“Today’s announcement should be a reminder to all Pennsylvanians to use a personal insect repellant or stay indoors during dawn and dusk will help prevent exposure to the mosquitoes that can carry West Nile Virus,” said DEP Secretary Patrick McDonnell. “DEP monitors mosquito populations across Pennsylvania for the presence of disease.”

The mosquitoes that transmit WNV breed in areas with standing and stagnant water. These areas can include urban catch basins, clogged gutters, discarded tires, poorly maintained swimming pools, flower pots and other types of plastic containers.

Individuals can take a number of precautionary measures around their homes to help eliminate mosquito-breeding areas, including:

-- Dispose of cans, buckets, plastic containers, ceramic pots, or similar containers that hold water.

-- Properly dispose of discarded tires that can collect water. Stagnant water is where most mosquitoes breed.

-- Drill holes in the bottom of outdoor recycling containers.

-- Have clogged roof gutters cleaned every year as the leaves from surrounding trees have a tendency to plug drains.

-- Turn over plastic wading pools when not in use.

-- Turn over wheelbarrows and don't let water stagnate in birdbaths.

-- Aerate ornamental pools or stock them with fish.

-- Clean and chlorinate swimming pools not in use and remove any water that may collect on pool covers.

If a resident has stagnant pools of water on their property, they can buy Bti (short for Bacillus thuringiensis subspecies israelensis) products at lawn and garden, outdoor supply, home improvement and other stores. This naturally occurring bacterium kills mosquito larvae, but is safe for people, pets, aquatic life and plants.

Additionally, these simple precautions can prevent mosquito bites, particularly for people who are most at risk:

-- Make sure screens fit tightly over doors and windows to keep mosquitoes out of homes.

-- Consider wearing long-sleeved shirts, long pants and socks when outdoors, particularly when mosquitoes are most active at dawn and dusk, or in areas known for having large numbers of mosquitoes.

-- When possible, reduce outdoor exposure at dawn and dusk during peak mosquito periods, usually April through October.

-- Use insect repellents according to the manufacturer's instructions. An effective repellent will contain DEET, picardin, or lemon eucalyptus oil. Consult with a pediatrician or family physician for questions about the use of repellent on children, as repellent is not recommended for children under the age of two months.

For more information about West Nile virus and the state's surveillance and control program, please visit the West Nile Virus website.  Click Here for a Department of Health fact sheet on West Nile Virus.