LONDON (AP) — Scientists who have monitored numerous monkeypox outbreaks in Africa say they are baffled by the disease's recent spread in Europe and North America.

Cases of the smallpox-related disease haven't previously been seen among people with no links to central and West Africa.

But in the past week, Britain, Spain, Portugal, Italy, the United States, Sweden, and Canada have all reported infections, mostly in young men who hadn't traveled to Africa.

On Wednesday, health officials in Massachusetts reported a case of monkeypox in a man who recently traveled to Canada.

They said the Massachusetts resident's case poses no risk to the public.

Health officials said the man was hospitalized but was in good condition.

On Friday, France, Germany, Belgium, and Australia all confirmed their first cases of monkeypox.

One of the theories British health officials are exploring is whether the disease is being sexually transmitted.

Monkeypox and smallpox are part of the same family of viruses.