As multiple cases of monkeypox are identified in Europe and North America, several scientists who have tracked many outbreaks in Africa say the strange disease’s spread in developed countries bewilders them.
Cases of the smallpox-related disease have not previously been seen among people with no links to Central and West Africa.
France, Germany, Belgium and Australia confirmed their first cases of monkeypox on Friday.
In the past week, the UK, Spain, Portugal, Italy, US, Sweden and Canada all reported infections, mostly in young men who had not previously traveled to Africa.
“I’m stunned by this,” said Oyewale Tomori, a virologist who formerly headed the Nigerian Academy of Science and who sits on several World Health Organization (WHO) advisory boards.
“Every day I wake up and there are more countries infected,” Tomori said.
“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.
Monkeypox typically causes fever, chills, a rash and lesions on the face or genitals. The WHO estimates the disease is fatal for about one in 10 people, but smallpox vaccines are protective and some antiviral drugs are also being developed.
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, but said the risk to the general population is low.
Outbreaks in Nigeria, which reports about 3,000 monkeypox cases a year, are usually in rural areas, where people have close contact with infected rats and squirrels, according to Tomori. He said the disease is not spread very easily and that many cases are likely missed.
“Unless the person ends up in an advanced health centre, they don’t attract the attention of the surveillance system,” he said.
Tomori hoped the appearance of monkeypox cases across Europe and other countries would further scientific understanding of the disease.
The WHO’s European chief said he was concerned that monkeypox could spread as people gather for parties and festivals over the summer months.
“As we enter the summer season in the European region, with mass gatherings, festivals and parties, I am concerned that transmission could accelerate, as the cases currently being detected are among those engaging in sexual activity, and the symptoms are unfamiliar to many,” WHO regional director for Europe Hans Kluge said on Friday.
The WHO’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”.
On Friday, the UK’s Health Security Agency reported 11 new monkeypox cases, saying that “a notable proportion” of the most recent infections in the UK and Europe have been in young men with no history of travel to Africa who 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.