Days after unusual clusters of the rare monkeypox virus emerged in Europe, New York City health authorities announced on Thursday that they were investigating a possible case of the rare disease.

The authorities said little about the patient, who is currently in isolation at Bellevue Hospital, according to a statement from the city health department. The patient arrived to the hospital Thursday, according to one official.

Patient samples will be sent to the city’s public health lab for a preliminary test, and if that comes back positive, samples will be sent to the Centers for Disease Control and Prevention to confirm whether the illness is in fact monkeypox, according to the health authorities.

News of the possible case comes a day after a man in Massachusetts was diagnosed with the disease. He had recently traveled to Canada, which is currently investigating more than 15 suspected cases in and around Montreal.

Clusters of monkeypox cases have recently been identified in Britain and Portugal, while Spain is investigating suspected cases of the virus. Sweden and Italy reported cases on Thursday. The patients in Britain and those in Canada are mostly men who have sex with men.

Monkeypox, according to the C.D.C., can spread through respiratory droplets from an infected person, as well through contact with body fluids and the sores that the virus is known for. It can also spread via contaminated objects.

The viral disease is related to smallpox, but it’s milder and less infectious. It usually does not cause large outbreaks.

The first outbreak in the United States occurred nearly 20 years ago and most likely infected some 47 people. It is believed to have begun with the importation of infected squirrels and other rodents from Ghana. They in turn infected prairie dogs that were subsequently sold as pets.

Infected people usually experience fever and body aches before developing the disease’s characteristic rash. Red bumps turn to pus-filled blisters that crust over. The illness can be treated with an antiviral drug.

The city’s health authorities on Thursday said that investigators will try to locate people who were recently in contact with the patient at Bellevue.