Monkeypox is a new global threat. African scientists know what the world is facing | Science

While monkeypox fuels fears of returning to a pandemic-weary world, some researchers in Africa are having their own sense of déjà vu. Another neglected tropical disease of the poor only gets attention after it begins to infect people in rich countries. “It’s like your neighbor’s house is on fire and you close the window and say it’s okay,” says Yap Boum, an epidemiologist in Cameroon who works with both the health ministry and Doctors Without Borders.

Now the fire is spreading. The global outbreak of monkeypox, which causes skin lesions similar to smallpox but is usually not fatal, emerged on 7 May in the UK. More than 700 suspected and confirmed cases had been reported as of May 31, from all continents except Antarctica. It is the largest outbreak ever recorded outside of Africa and is concentrated among men who have sex with men, a phenomenon never seen before. Public health officials and scientists are scrambling to understand how the virus spreads and how to stop it, and are paying new attention to Africa’s long experience with the disease.

“We are interdependent,” notes Boum. “What is happening in Africa will certainly have an impact on what is happening in the West and vice versa.”

Monkeypox is endemic in 10 countries in West and Central Africa, with dozens of cases this year in Cameroon, Nigeria and the Central African Republic (CAR). The Democratic Republic of the Congo (DRC) has by far the highest burden, with 1284 cases in 2022 alone. These numbers are almost certainly underestimated. In the Democratic Republic of the Congo, infections most often occur in remote rural areas; in the CAR, armed conflict in several regions has limited surveillance.

The virus got its name after it was first identified in a colony of Asian monkeys in a laboratory in Copenhagen, Denmark in 1958, but has only been isolated once from a wild monkey in Africa. It appears to be more common in squirrel, rat, and shrew species, occasionally pouring into the human population, where it spreads primarily through close contact, but not through respiration. Isolating infected people typically helps to put an end to outbreaks quickly.

Cases have steadily increased in sub-Saharan Africa over the past 3 decades, largely driven by medical triumph. The vaccine against smallpox, a much more lethal and transmissible virus, also protects against monkeypox, but the world stopped using it in the 1970s, just before smallpox was declared eradicated. As a result, “There is a huge, huge number of people who are now susceptible to monkeypox,” says Placide Mbala, a virologist who heads the genomics laboratory at the National Biomedical Research Institute (INRB) in Kinshasa, in the Democratic Republic of the Congo.

Mbala says demographic changes have also fueled the increase. “People are increasingly moving into the forest to find food and build homes, and this increases the contact between wildlife and the population,” she says. Studies in CAR have shown an increase in cases after villagers moved to the forest during the rainy season to collect caterpillars which are sold for food. “When they stay in the bush they easily come into contact with the animal reserve,” says virologist Emmanuel Nakouné, scientific director of the Pasteur Institute in Bangui, who in 2018 launched a program called Afripox with French researchers to better understand and fight smallpox in the monkeys.

Outbreaks outside Africa, including the current one, have all involved the West African strain, which kills about 1% of those it infects. The Congo Basin strain, found in the Democratic Republic of the Congo and the Central African Republic, is 10 times more lethal, but despite the relatively high disease burden in the Democratic Republic of the Congo, it has never left Africa. But it has never caused a serious outbreak even in a Congolese city, which underlines the isolation of the areas where it is endemic. “It’s kind of a self-quarantine,” Mbala says. “Those people are not moving from the Democratic Republic of the Congo to other countries.”


The monkeypox virus infects squirrel, rat and shrew species in at least 10 countries in West and Central Africa and occasionally leaps into the human population. So far this year, five countries have reported human cases.

(Graphic) K. Franklin /Science; (Data) World Health Organization

It is unclear where the current epidemic began and how long ago. “It’s kind of like we’ve tuned in to a new TV series and we don’t know what episode we ended up in,” says Anne Rimoin, an epidemiologist at the University of California, Los Angeles, who worked on monkeypox in the Democratic Republic of the Congo for 20 years. The first patient with an identified case traveled from Nigeria to the UK on May 4, but does not appear to have infected anyone else. Two patients diagnosed later, one in the United States and the other in the United Arab Emirates, had also recently traveled to Africa and possibly imported the virus separately. But none of the other cases identified in recent weeks have links to infected travelers or animals from endemic countries. Instead, many of the earliest cases were linked to transmission at gay festivals and saunas in Spain, Belgium and Canada.

Some suspect the virus may have been imported from Nigeria, the most populous country in Africa, which has good infrastructure linking rural areas to large cities and two of Africa’s busiest airports. But this is “highly speculative,” points out Christian Happi, who runs Nigeria’s African Center of Excellence for Infectious Disease Genomics. Happi urges people in other countries to “not point fingers”, but to cooperate.

Epidemiologist Ifedayo Adetifa, head of the Nigerian Center for Disease Control, says the country receives undue attention because it does more surveillance than its neighbors and shares what it finds. “There is too much emphasis, for whatever reason, in Western capitals and the news media on trying to hold someone responsible for a particular outbreak,” he says. “We don’t think those narratives are useful.” Adetifa says that although Nigeria has recently seen “an increase in cases”, he is confident that a large number is not missing. “We are literally shaking the bushes to see what comes out of it.”

Viruses on the rise

In the 4 decades since the world stopped vaccinating against smallpox, suspected and confirmed cases of monkeypox in Africa have steadily increased.

(Graphic) K. Franklin /Science; (Data) EM Bunge et al., PLOS has neglected tropical diseases16 (2): e0010141 (2022)

The ability of African countries to deal with monkeypox was improving even before the current epidemic. The DRC has stepped up its surveillance across the vast country, which is key to isolating infected people and tracking the virus’ moves. The INRB and a lab in Goma can now diagnose samples using the polymerase chain reaction test, and the researchers eventually hope to develop rapid tests for use in clinics nationwide. The INRB and labs in Nigeria can also sequence the entire genome of the virus, and Nigeria plans to make the genomes of several recent monkeypox isolates public, Adetifa says. Those and other sequences from Africa could help researchers pinpoint the source of the international outbreak by building viral family trees.

For now, there is a lack of medicines in Africa to prevent and treat monkeypox. In the UK and US, high-risk case contacts are offered a vaccine manufactured by Bavarian Nordic that was approved for monkeypox by the US Food and Drug Administration in 2019, but is not available anywhere in Africa. . The US Centers for Disease Control and Prevention and collaborators in the Democratic Republic of the Congo are testing the vaccine in healthcare workers; the 2019 approval was based on animal studies.

In CAR, 14 people with monkeypox received an investigational drug, tecovirimat, as part of a trial launched by the University of Oxford in July 2021. “We’ve had excellent results,” says Nakouné, who says he expects the data to be published in the coming weeks. The manufacturer of the drug, SIGA, has pledged to provide up to 500 treatment courses in the country.

Although the international epidemic has, once again, highlighted global health inequalities, it has also brought much-needed attention to the smoldering disease in Africa. “It was really hard to get the resources to do the kind of background work that really needs to be done and that’s not a problem, in the context of an emergency,” says Rimoin. “We can’t keep hitting the snooze button. Now the stakes are really high. “

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