Monkeypox virus has sparked concerns in at least nine European nations - Belgium, France, Germany, Italy, the Netherlands, Portugal, Spain, Sweden and the United Kingdom - with cases having been reported from the United States, Canada and Australia too.
While the WHO held an emergency meeting on Friday, a top health official has sounded a warning that cases could "accelerate". "As we enter the summer season... with mass gatherings, festivals and parties, I am concerned that transmission could accelerate," WHO regional director for Europe Hans Kluge has been quoted as saying by news agency AFP.
The spread, Kluge has said, seems "atypical". "All but one of the recent cases have no relevant travel history to areas where monkeypox is endemic," he added.
Nearly 100 cases are confirmed or suspected in Europe.
In Spain, 24 new cases were recorded on Friday, taking the total count past 30. A sauna in Madrid has been forced to close over a suspected link to the outbreak. "The Paraiso sauna will remain closed for the next few days, a precautionary measure in the face of the alert... over the emergence of so-called monkeypox infections in the Madrid region," a Twitter post read.
"This is the largest and most widespread outbreak of monkeypox ever seen in Europe," Germany's armed forces' medical service was quoted as saying by news agency Reuters. The European nation reported its first case in the country on Friday.
"Monkeypox is a sylvatic zoonosis with incidental human infections that usually occur in forested parts of Central and West Africa. It is caused by the monkeypox virus which belongs to the orthopoxvirus family," the WHO says.
The transmission usually occurs "by droplet exposure via exhaled large droplets and by contact with infected skin lesions or contaminated materials. The incubation period of monkeypox is usually from 6 to 13 days but can range from 5 to 21 days. The disease is often self-limiting with symptoms usually resolving spontaneously within 14 to 21 days," says the world health body.
There seems to be "low public risk" at this time, a senior US administration official has said.
Transmission may have been going on for some time, health officials suspect, while it is also being studied further that most cases are being spread due to intimate contact.
The monkeypox virus, which has been largely reported from African nations so far, is not likely to spread like Covid.
"However, it is very unlikely that this epidemic will last long. The cases can be well isolated via contact tracing and there are also drugs and effective vaccines that can be used if necessary," Fabian Leendertz from the Robert Koch Institute was quoted as saying by news agency Reuters.