BERKELEY HEIGHTS, N.J. (CBSNewYork) – New Jersey health officials say two new cases of a deadly mosquito-borne virus have been diagnosed in the state.

There are now three confirmed human cases of Eastern Equine Encephalitis in New Jersey. The first case was found back in August.

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EEE is rare and serious illness transmitted to humans by a mosquito bite and has already killed at least three people in the U.S. this year.

The CDC says on average, seven people contract EEE in the U.S. each year.

So far this year there are at least 20 human cases reported across six states – including Connecticut and New Jersey. Deaths have been reported in Michigan, Massachusetts, and Rhode Island.

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The Connecticut Department of Public Health says mosquitoes in 12 towns have also tested positive for Eastern Equine Encephalitis.

Health officials add that there is also no human vaccine for EEE, making it even more dangerous.

In severe cases, the virus can cause swelling in the brain, leading to death.

Common symptoms include fever, chills, and muscle and joint pain.

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According to the CDC, about a third of infected patients die and many who survive experience ongoing neurological problems.