TRENTON, N.J. (AP) — New Jersey has its first probable case of the rare monkeypox virus.

The state’s Department of Health announced Monday that a test confirmed the presence of orthopoxvirus in a person in northern New Jersey on Saturday. A further test to confirm the virus will be performed by the U.S. Centers for Disease Control and Prevention.

The affected person is isolating at home and contact tracing is being performed to determine others who may have been exposed. Monkeypox has been identified in 20 states and the District of Columbia.

It can spread through close, prolonged contact with an affected person or animal.