(CNN) A rare virus spread by ticks has caused a fatality in New York, health officials in Ulster County said Thursday.

A resident of Gardiner, New York, became the first diagnosis of Powassan virus in the state this year. The victim of the virus did have an underlying condition, the health department said.

Though rare, the virus -- which cannot be treated with antibiotics -- is often serious, according to the Ulster County Health Department.

Authorities in Ulster County are urging residents to be on alert for ticks that could carry Powassan.

"It is imperative that all residents take every precaution necessary against tick-borne illnesses, especially during outdoor activities. Residents should vigilantly check themselves and their pets for ticks and tick bites," Dr. Carol M. Smith, Ulster County Commissioner of Health and Mental Health, said in a statement.

Read More