A Massachusetts Man Is Infected With Monkeypox

A man who had traveled to Canada has been diagnosed with the monkeypox virus, a rare and potentially fatal disease, the Massachusetts Department of Public Health reported on Wednesday.

This is the first report of monkeypox this year in the United States. Officials in Texas and Maryland recorded one case each last year. But the new case follows a series of unusual clusters in other countries that have begun to alarm public health officials.

In the past few weeks, Britain has identified nine monkeypox cases. Only one patient had recently traveled — to Nigeria, where a strain of the monkeypox virus has been commonly seen — while the remaining British patients, who did not travel, may have acquired the infection through community transmission. Three patients shared a household.

Spain has 23 suspected cases. Portugal has confirmed five cases and is investigating another 15. Canadian health officials are investigating at least 15 possible cases in Montreal, according to an infectious disease specialist who was familiar with the effort but was not authorized to discuss the matter publicly.