The Wolf administration on Saturday warned Pennsylvanians that a rare but dangerous mosquito-borne brain disease has been confirmed in three counties — Erie, Carbon, and Monroe.

Eastern equine encephalitis, or Triple E, is a virus transmitted to humans and horses by the bite of an infected mosquito. Mosquitoes pick up the virus from birds. Triple E kills three of every 10 people who get it and leaves most survivors with brain damage, according to state officials.

New Jersey officials said Thursday that three cases of the disease — in Atlantic, Somerset, and Union Counties — had been recorded. The disease was found in 65 mosquito samples in the state.

Nationwide, health officials have reported 18 cases to the federal Centers for Disease Control and Prevention, compared with six last year. Fatal cases were reported in Connecticut and Massachusetts this month.

Pennsylvania’s confirmed cases include a wild turkey, pheasants, and horses, officials said.

In humans, severe cases of disease, which include inflammation of the brain, begin with high fever, chills, headache, and vomiting four to 10 days after a mosquito bite. In a more advanced state, the illness may cause disorientation, seizures, or coma.