Mosquito Season Brings West Nile Risk to Humans, Horses

Wear Insect Repellant, Eliminate Standing Water to keep Mosquitoes Away

Pennsylvania state officials recently reminded residents to take precautions against West Nile virus during the upcoming mosquito season.

"It's that time of the year again for people to take steps to reduce their risk of becoming infected with West Nile virus," says Pennsylvania Health Secretary Dr. Calvin B. Johnson. "If you are going to be outside, remember to use insect repellant containing DEET - especially during dawn and dusk - and wear long sleeves and light-colored clothing."

While most people infected do not get sick, a small percentage of those infected will experience a fever, rash, headache, meningitis (inflammation of the tissue surrounding the brain), encephalitis (inflammation of the brain) or even death, according to the Centers for Disease Control and Prevention.

Anyone is at risk, but older adults and people with compromised immune systems have the highest risk of developing severe illness because their bodies have a harder time fighting off disease.

West Nile virus cases occur primarily in the late summer or early fall, although mosquito season is usually April through October. The Department of Environmental Protection is coordinating the mosquito surveillance and control portion of the multi-agency effort.

"DEP staff is working with county coordinators to keep the mosquitoes under control, but you can take some simple steps in your backyard to help," said Environmental Protection Secretary Kathleen A. McGinty. "Remember: dump it if it has water in it; drain it if it can be drained; and treat it if it has standing water. Do these simple things and you can go a long way to protect yourself and your family."

Last year in Pennsylvania, 266 mosquito pools tested positive for the virus from many areas of the commonwealth. In 2004, there where 164 West Nile virus-positive pools.

DEP and county West Nile coordinators will be looking for immature (larvae and pupae) and adult mosquitoes to determine if they are the species known to carry the virus. They also will be noting their number and geographic distribution. If sufficient numbers of these mosquitoes are detected, they will be controlled using a powdered form of naturally occurring bacteria or a mosquito growth hormone, both of which are harmless to humans and other aquatic life.

"Similar to people, animals become infected with the West Nile virus only after being bitten by an infected mosquito," Agriculture Secretary Dennis C. Wolff said. "Horses are most susceptible to illness after exposure, and we will continue to work with veterinarians and horse owners across the state to monitor horse populations."

Wolff also noted that people can take a few simple steps in their own backyards to reduce their risk of contracting the West Nile virus. Mosquitoes will develop in any puddle that lasts for more than four days. Tips to eliminate standing water:

  • Dispose of tin cans, plastic containers, ceramic pots or similar water-holding containers that have accumulated on your property. Pay
    special attention to discarded tires that may have accumulated on your property
  • Drill holes in the bottom of containers that are left outdoors. Drainage holes that are located on a container's sides allow them to collect enough water for mosquitoes to breed
  • Clean clogged roof gutters on an annual basis
    Turn over plastic wading pools, wheelbarrows and birdbaths when not in use
    Aerate ornamental pools or stock them with fish;
    Clean and chlorinate swimming pools that are not being used. Mosquitoes may even breed in water that collects on swimming pool covers
  •  Use landscaping to eliminate standing water that collects on your

West Nile virus is common in parts of the Middle East, Africa and West Asia. The virus was first detected in the U.S. in 1999 in New York.

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