Eastern Equine Encephalitis confirmed in three PA counties

closeup of horse grazing

HARRISBURG, Pa. — The Pennsylvania Departments of Agriculture and Health warned Pennsylvanians Sept. 21 to take precautionary measures against mosquito bites for themselves and their animals — specifically horses — as the rare, mosquito-transmitted, viral infection Eastern Equine Encephalitis has been confirmed in Erie, Carbon and Monroe counties.

The disease is a virus carried by birds. If a mosquito bites an infected bird it can then transmit the potentially fatal virus to humans, horses and other birds. Because of the high mortality rate in horses and humans, EEE is regarded as one of the most serious mosquito-borne diseases in the United States.

Through mid-September, there have been 18 cases reported to the Center for Disease Control and Prevention from across the country in 2019, with the majority of the cases in northeastern or Mid-Atlantic states. Several cases have been fatal.

Avoiding mosquitoes

When outdoors, people can avoid mosquito bites by properly and consistently using insect repellents 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.

Homeowners should eliminate standing water around their property to reduce mosquito populations. Here are some simple steps you can take:

  • Remove tin cans, plastic containers, ceramic pots, discarded tires or any object that could collect standing water.
  • Drill holes in the bottom of recycling containers left outdoors.
  • Have roof gutters cleaned annually, particularly if leaves from nearby trees have a tendency to clog the drains.
  • Turn over plastic wading pools and wheelbarrows when not in use.
  • Do not let water stagnate in bird baths.
  • Aerate ornamental pools or stock them with fish.
  • Clean and chlorinate swimming pools and remove standing water from pool covers.
  • Use landscaping to eliminate standing water that collects on your property.
  • Treat standing water that cannot be eliminated with Bti products, which are sold at outdoor supply, home improvement and other stores. Bti is a natural product that kills mosquito larvae, but is safe for people, pets, aquatic life and plants.

Human symptoms

The symptoms of EEE are a high fever, stiff neck, headache and lack of energy. These symptoms typically show up three to 10 days after being bitten by an infected mosquito. Inflammation and swelling of the brain, called encephalitis, can develop.

The disease gets worse quickly, and some patients end up in a coma within a week. This disease can also be fatal. Three out of every 10 people who get the disease die from it.

Equine symptoms

In addition to eliminating standing water on their properties, horse owners can vaccinate against both EEE and West Nile Virus, keep animals indoors at night and spray for mosquitoes. Vaccines for Western, Venezuelan and Eastern Equine Encephalitis are available from veterinarians.

Symptoms in horses start with a fever that may reach as high as 106 degrees Fahrenheit for one to two days. Additional symptoms can include abnormal gait, aimless wandering, circling, difficulty breathing, drooping ears, drowsiness, head pressing, hyperactivity, inability to swallow, paralysis, restlessness, sensitivity to sound and death.

Pennsylvania’s recently confirmed cases include a wild turkey, pheasants and horses. Pennsylvanians should immediately contact their physician or veterinarian if symptoms present.

For more information visit www.health.pa.gov or www.agriculture.pa.gov.


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