A senior advisor to the World Health Organization described the unprecedented outbreak of rare monkeypox in developed countries as a “random event” that could be explained by risky sexual behavior in two recent mass events in Europe.
In an interview with the Associated Press, Dr. David Heymann, who formerly headed the WHO’s emergency department, said the main theory to explain the disease’s spread was sexual transmission between gay and bisexual men at two parties in Spain and Belgium. Monkeypox has never before caused a large-scale outbreak outside of Africa, where the animals are endemic.
“We know that monkeypox can spread when there is close contact with the wounds of an infected person, and sexual contact now appears to amplify that transmission,” Heymann said.
This represents a significant departure from the usual pattern of outbreaks in Central and West Africa, where people are primarily infected by animals such as wild rodents and primates, and the outbreak has not spread across borders.
The World Health Organization has so far recorded more than 90 cases of monkeypox in 12 countries, including Britain, Spain, Israel, France, Switzerland, the United States and Australia.
A senior health official in Madrid said, on Monday, that the Spanish capital has recorded 30 confirmed cases of infection so far. Enrique Ruiz Escudero said authorities are investigating possible links between the recent “Guy Pride” event in the Canary Islands, which drew some 80,000 people, and cases in a sauna in Madrid.
Heymann chaired an urgent meeting of the World Health Organization’s advisory group on infectious disease threats on Friday to assess the ongoing epidemic and said there was no evidence to suggest monkeypox may have mutated into a more contagious form.
Monkeypox usually causes fever, chills, rash, and lesions on the face or genitals. It can be spread through close contact with an infected person or their clothing or bed linen, but sexual transmission has not been documented. Most people recover from the disease within several weeks without requiring hospitalization. Vaccines against smallpox, a related disease, are also effective in preventing monkeypox, and some antiviral drugs are being developed.
In recent years, the disease has been fatal in up to 6% of infections, but no deaths have been reported among the current cases. The World Health Organization said the confirmed cases were so far the least dangerous group of monkeypox viruses in West Africa and appeared to be linked to a virus first detected in cases exported from Nigeria to Britain, Israel and Singapore in 2018-2019.
The UN agency said the outbreak was a “very unusual event” and said the fact that cases had emerged in so many different countries suggested the disease may have been spreading silently for some time. The acting director of Europe has warned that as summer rolls around the continent, mass gatherings, festivals and parties could accelerate the spread of monkeypox.
Other scientists have pointed out that it would be difficult to separate whether it was sex itself or close contact linked to sex that led to the recent spread of monkeypox across Europe.
“By its nature, sexual activity includes intimate contact, which one would expect to increase the likelihood of transmission, regardless of a person’s sexual orientation and regardless of the mode of transmission,” said Mike Skinner, a virologist at Imperial College London.
On Sunday, Britain’s Health Security Agency’s chief medical adviser, Dr Susan Hopkins, said she expected more cases of monkeypox to be discovered in the country “on a daily basis”.
British officials said a “significant proportion” of cases in Britain and Europe were of young men with no history of travel to Africa and of gay, bisexual or male sex. Authorities in Portugal and Spain also said their cases were of men who had mostly sex with other men and their infections were picked up when they sought help at sexual health clinics.
Heyman, who is also a professor of infectious diseases at the London School of Hygiene and Tropical Medicine, said the monkeypox outbreak was likely a random event that could be traced back to a single infection.
Hyman postulated: “It is very likely that someone got an infection, developed lesions on the genitals, hands, or elsewhere, and then spreads it to others when there was physical or sexual contact or close contact.” “And then there were these international events that seeded the spread of the disease all over the world, in the United States and other European countries.”
He stressed that the disease is unlikely to lead to widespread transmission.
“This is not Covid,” he said. “We need to slow it down, but it’s not spreading in the air and we have vaccines to protect against it.” Heymann said studies should be done quickly to determine whether monkeypox can be spread by people who don’t have symptoms and that populations at risk for the disease should take precautions to protect themselves.
Barry Hatton in Lisbon contributed to this report.
Maria Cheng, The Associated Press