HARRISBURG, Pa. - Eastern Equine Encephalitis — a rare mosquito-transmitted illness considered worse than West Nile Virus — has been found in three Pennsylvania counties, officials announced Saturday.
The illness, referred to more succinctly as Triple E, was discovered in Erie, Carbon and Monroe counties.
The number of U.S. deaths and illnesses from a rare mosquito-borne virus are higher than usual this year, health officials report.
Eastern equine encephalitis has been diagnosed in 21 people in six states, and five people have died. The infection is only being seen in certain counties within a small number of states.
The U.S. each year has seen seven illnesses and three deaths, on average.
- Mosquito-transmitted Triple E illness confirmed in Delaware
- Uptick seen in rare mosquito-borne illness leaves 5 dead
- Eastern Equine Encephalitis confirmed in New Jersey
It's not clear why numbers are up this year, but for some reason cases seem to spike once every several years, according to Dr. Mark Fischer, an expert at the U.S. Centers for Disease Control and Prevention.
The virus is spread to people through mosquitoes that mostly feed on infected birds but sometimes bite humans. Few people who are infected get sick but those who do can develop a dangerous infection of the brain, spinal cord or surrounding tissues.
Cases are generally confined to New England and states along the Gulf of Mexico or Great Lakes, usually in or near swamps.
The uptick in cases has prompted health warnings in some places and even calls to cancel outdoor events scheduled for dusk - when mosquitoes are most active. Precautions include using mosquito repellent and wearing long sleeved shirts and long pants outdoors.
Scientists first recognized eastern equine encephalitis as a horse disease in Massachusetts. There's a vaccine for horses, but not people.
The Associated Press contributed to this report.