Scientists who have tracked numerous outbreaks of monkeypox in Africa say they are confused by the recent spread of the disease in Europe and North America.
Cases of smallpox have previously been observed only among people with ties to Central and West Africa. But last week the UK, Spain, Portugal, Italy, the US, Sweden and Canada reported infections, mostly in young men who had not previously traveled to Africa.
France, Germany, Belgium and Australia confirmed their first cases on Friday.
“I’m stunned by this. Every day I wake up and more and more countries are infected,” said Oyevale Tomori, a virologist who previously headed the Nigerian Academy of Sciences and is a member of several advisory boards of the World Health Organization.
“It’s not the kind of proliferation we’ve seen in West Africa, so something new could happen in the West,” he said.
To date, no one has died from the epidemic. Smallpox usually causes fever, chills, rashes and lesions on the face, hands or genitals. The WHO estimates that the disease is fatal to 1 in 10 people, but smallpox vaccines are protective and some antiviral drugs are being developed.
British health officials are studying whether the disease is sexually transmitted. Health officials asked doctors and nurses to be alert to possible cases, but said the risk to the general population was low. The European Center for Disease Control and Prevention has recommended isolating all suspected cases and offering high-risk vaccines to people at high risk.
Nigeria reports 3,000 cases of monkeypox a year, the WHO said. Outbreaks are common in rural areas when people come into close contact with infected rats and proteins, Tomori said. He said many cases were probably missed.
Dr Ifedayo Adetifa, head of the country’s Centers for Disease Control, said that none of the Nigerian contacts of British patients had symptoms and that the investigation was ongoing.
WHO Director-General for Europe Dr Hans Kluge described the outbreak as “atypical”, saying the outbreak in many countries on the continent indicated that “transmission has been going on for some time”. He said that most European cases are mild.
The British Health Agency on Friday reported 11 new cases of monkeypox, saying a “significant portion” of recent infections in the UK and Europe had come from young people who had not traveled to Africa who had sex with men. The Spanish and Portuguese authorities said their cases were the same.
Experts stressed that they do not know whether the disease is spread through sex or other close contacts related to sex.
Tomori said there was no sexual transmission in Nigeria, but he noted that viruses that were not initially known to be sexually transmitted, such as Ebola, were later shown to occur after larger epidemics showed different distribution patterns.
The same can be said with monkeypox, Tomori said.
In Germany, Health Minister Karl Lauterbach said the government was confident the outbreak could be contained. He said the virus was sequenced to find out if there were any genetic changes that could make it more contagious.
Rolf Gustafson, a professor of infectious diseases, told Swedish TV company SVT that it was “very difficult” to imagine that the situation could get worse.
“We will, of course, find some other cases in Sweden, but I don’t think there will be an epidemic in any way,” Gustafson said. “There is currently no evidence of this.”
Scientists have said that while it is possible that the first patient of the epidemic became infected in Africa, what is happening now is exceptional.
“We have never seen anything like this in Europe,” said Christian Happy, director of the African Center for Excellence in Infectious Genomics. “We haven’t seen anything to say that monkeypox transmission schemes have changed in Africa. So if something else is happening in Europe, then Europe needs to investigate it.”
Hapi also noted that the suspension of smallpox vaccination campaigns after the eradication of the disease in 1980 may inadvertently contribute to the spread of smallpox. Smallpox vaccines also protect against monkeypox, but mass immunization was stopped decades ago.
“Apart from people in West and Central Africa who may have some immunity to smallpox due to previous exposure, the lack of smallpox vaccination means that no one is immune to smallpox,” said Happy.
Shabir Mahdi, a professor of vaccinology at the University of the Witwatersrand in Johannesburg, said a detailed investigation into the outbreak in Europe, including the identification of the first patients, is now crucial.
“We need to really understand how it started and why the virus is gaining momentum,” he said. “There have been very controlled and rare outbreaks of monkeypox in Africa. If that is changing now, we really need to understand why. ”