The World Health Organization on Friday said it was stepping up efforts to understand and combat monkeypox as nearly a dozen countries are investigating a “atypical” outbreaks. The organization said the ongoing situation is being discussed at several meetings.

“There are about 80 confirmed cases so far, and 50 pending investigations. More cases are likely to be reported as surveillance expands,” the health agency said in a news release.

The spike in monkeypox cases in Europe and North America has perplexed public health professionals because the rare disease is typically found in central and west Africa — and human-to-human transmission is usually considered uncommon. 

The U.S. has recorded one case of monkeypox, in Massachusetts on Wednesday, and a suspected case in New York City on Thursday.

The list of countries with at least one monkeypox case also includes: Australia, Belgium, Canada, France, Germany, Italy, Portugal, Spain, Sweden and the United Kingdom.

Those at highest risk are people who closely interact with someone infected with the generally mild disease.  

“This includes health workers, household members and sexual partners,” WHO said.

But experts say the outbreak is not likely to evolve into a global health crisis because the disease is not easily transmitted and reported cases remain relatively low. 

“It doesn’t have that great a transmission ability,” said Dr. Seth Blumberg, an infectious disease specialist at the University of California, San Francisco.

WATCH:Case of monkeypox reported in Massachusetts

“Monkeypox usually does not occur globally,” Dr. Anne W. Rimoin, a professor of epidemiology at the UCLA Fielding School of Public Health, told USA TODAY. Rimoin, who has extensively studied monkeypox and other infectious diseases in Central Africa, said such outbreaks are “rare and unusual occurrence.”