Belgium introduced a compulsory 21-day monkeypox quarantine after three cases of the disease were discovered in the small European nation last week.

Fourteen nations now have recorded cases of the smallpox-like disease, according to the Daily Mail.

The Belgian cases were linked to a festival for gay men that took place in Antwerp.

"There's reason to assume that the virus has been brought in by visitors from abroad to the festival after recent cases in other countries," organizers of The Darklands Festival posted on its website, according to Newsweek.

On Saturday, the microbiologist Emmanuel André said a fourth person in Belgium had been found with monkeypox, according to Politico.

WHO Regional Director for Europe Dr. Hans Kluge said Friday that the virus may keep spreading during summer festivals and parties, Newsweek reported.

As of Saturday, there were 92 confirmed cases and 28 suspected cases of monkeypox in 12 nations where the disease is not normally found, the Daily Mail reported.

Monkeypox results in lesions on the skin, as well as a fever, sore muscles and a headache.

Professor David Heymann of The London School of Hygiene & Tropical Medicine said the disease is spreading in a new way.

"What seems to be happening now is that it has got into the population as a sexual form, as a genital form, and is being spread as are sexually transmitted infections, which has amplified its transmission around the world," he said.

Dr. Claire Dewsnap, the president of the British Association for Sexual Health and HIV, told The Express that cases are only going to grow.

“There is going to be more diagnoses over the next week,” she said. “How many is hard to say. What worries me the most is there are infections across Europe, so this has already spread.”

“It's already circulating in the general population. Getting on top of all those people's contacts is a massive job,” she explained.

The disease has already reached the United States.

One monkeypox infection has been confirmed in Massachusetts, and at least one of two New York City cases is suspected of being monkeypox, according to CNN.

One expert said the spread is a surprise, according to the Associated Press.

“I’m stunned by this. Every day I wake up, and there are more countries infected,” said Oyewale Tomori, a virologist and former head of the Nigerian Academy of Science.

“This is not the kind of spread we’ve seen in West Africa, so there may be something new happening in the West,” he said.

“We’ve never seen anything like what’s happening in Europe,” said Christian Happi, director of the African Centre of Excellence for Genomics of Infectious Diseases. “We haven’t seen anything to say that the transmission patterns of monkeypox have been changing in Africa. So if something different is happening in Europe, then Europe needs to investigate that.”

This article appeared originally on The Western Journal.