Israel's Health Ministry said late Saturday the man was in a Tel Aviv hospital in good condition. It called on anyone returning from abroad with fever and lesions to see a doctor.

Sharon Alroy-Preis, the head of public health services at the ministry, told Israeli Army Radio Sunday that medical teams were investigating other suspected monkeypox cases. Israel's case appeared to be the first identified in the Middle East.

The World Health Organisation has identified about 80 cases globally, and roughly 50 more suspected cases.

Cases of the smallpox-related disease have previously been seen only among people with links to central and West Africa. But Britain, Spain, Portugal, Italy, the US, Sweden and Canada all reported infections, mostly in young men who hadn't previously travelled to Africa. France, Germany, Belgium and Australia have also identified cases.

The virus originates in primates and other wild animals, and causes fever, body aches, chills and fatigue in most patients. People with severe cases can develop a rash and lesions on the face, hands and other parts of the body.

Some of the?scientists who have monitored numerous outbreaks in Africa say they are baffled by the unusual disease's spread in the West.

“I'm stunned by this. Every day I wake up and there are more countries infected,” said Oyewale Tomori, a virologist who formerly headed the Nigerian Academy of Science and who sits on several World Health Organization advisory boards.

“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.

One of the theories British health officials are exploring is whether the disease is being sexually transmitted. Health officials have asked doctors and nurses to be on alert for potential cases. Tomori hoped the appearance of monkeypox cases across Europe and other Western countries would further scientific understanding of the disease.

The World Health Organization's lead on emergency response, Dr. Ibrahima Soce Fall, acknowledged this week that there were still “so many unknowns in terms of the dynamics of transmission, the clinical features (and) the epidemiology”.

British officials have so far reported nine cases of monkeypox, noting that the most recent cases have all been in young men who had no history of travel to Africa and were gay, bisexual, or had sex with men.

Authorities in Spain and Portugal also said their cases were in young men who mostly had sex with other men and said those cases were picked up when the men turned up with lesions at sexual health clinics. Experts have stressed they do not know if the disease is being spread through sex, or other close contact related to sex.

In Germany, Health Minister Karl Lauterbach said the government was confident the outbreak could be contained. He said the virus was being sequenced to see if there were any genetic changes that might have made it more infectious. Scientists said that while it's possible the outbreak's first patient caught the disease while in Africa, what's happening now is exceptional.

“We've never seen anything like what's happening in Europe,” Christian Happi, director of the African Centre of Excellence for Genomics of Infectious Diseases, said. “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.”

Shabir Mahdi, a professor of vaccinology at the University of Witwatersrand in Johannesburg, said a detailed investigation of the outbreak in Europe, including determining who the first patients were, was now critical.

“We need to really understand how this first started and why the virus is now gaining traction,” he said. “In Africa, there have been very controlled and infrequent outbreaks of monkeypox. If that's now changing, we really need to understand why.”

(with inputs from AP)