PITTSBURGH (KDKA)– Doctors across the country are trying to figure out why so many people are getting sick with a deadly virus that’s spread by mosquitoes.

Cases are coming up in several states including Pennsylvania.

Eastern Equine Encephalitis (EEE) is on the rise. According to experts at the University of Pittsburgh, it can be extremely dangerous. Someone showing symptoms has a 30%-40% chance of dying.

“Which is extremely high for this kind of virus. They are usually below one percent,” Dr. William Klimstra from the university said.

If someone does survive, it can cause long-term issues.


“It’s a severe infection that has a tragic impact on people, and also extremely expensive to treat,” Dr. Klimstra said at one of Pitt’s Biomedical Towers in Oakland.

He has studied the virus for about 10 years and similar viruses for almost three decades. It’s so dangerous, medical researchers have to use HAZMAT suits to study it.

It’s deadly because people don’t know they are sick until it hits their brain. At that point, it causes extreme illness.

So far this year, there have been 30 cases in people nationwide, 11 deadly. According to the CDC, the last six years combined for about 40 cases.

“This is quite a bit higher than typical, but it’s not unprecedented,” Dr. Klimstra said.

He told KDKA the virus is cyclical and has peak years, 2019 being one of them.

This year is hitting levels not seen since the 1950s. Dr. Klimstra blames the recent wet weather and extended warm temperatures for giving mosquitoes more time to spread the virus.

“The cases start to show up in horses in June, maybe humans in July,” he said. “They peak through August, September, and the first killing frost it just goes away, and if it takes longer to get to that, there will be more cases.”

There is no vaccine for the deadly virus. Dr. Klimstra said there is not a high enough demand.

“The historic ways vaccines come into the market, just not enough people get the virus to have a market to bring a vaccine in,” he said.

So far in Pennsylvania, there are no cases in people. It’s been seen in animals in Erie and Mercer Counties. There have been other cases on the eastern side of the state.

The PA Department of Environmental Protection is spraying for mosquitoes in that area. They said those mosquitoes carrying the virus are not prevalent in Southwest Pennsylvania, so they are not spraying around there.

Dr. Klimstra said this threat of the virus should not stop you from going outside.

“It’s a very rare infection still.”