Science

Monkeypox is a new global threat. African scientists know what the world is up against

As monkeypox stokes here-we-go-again fears in a pandemic-weary world, some researchers in Africa are having their own sense of déjà vu. Another neglected tropical disease of the poor gets attention only after it starts to infect people in wealthy countries. “It’s as if your neighbor’s house is burning and you just close your window and say it’s fine,” 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 smallpoxlike skin lesions but is not usually fatal, surfaced on 7 May in the United Kingdom. More than 700 suspected and confirmed cases had been reported as of 31 May, from every continent other than Antarctica. It is the largest ever outbreak 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 they are paying new attention to Africa’s long experience with the disease.

“We are interdependent,” Boum notes. “What is happening in Africa will definitely impact 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. Those numbers are almost certainly underestimates. In the DRC, infections most often happen 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 Copenhagen, Denmark, laboratory in 1958, but it has only been isolated from a wild monkey—in Africa—once. It appears to be more common in squirrel, rat, and shrew species, occasionally spilling over into the human population, where it spreads mainly through close contact, but not through breathing. Isolating infected people typically helps outbreaks end quickly.

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

Mbala says demographic shifts have fueled the rise as well. “People are more and more moving to the forest to find food and to build houses, and this increases the contact between the wildlife and the population,” he says. Studies in the CAR showed cases spike after villagers move into the forest during the rainy season to collect caterpillars that are sold for food. “When they stay in the bush they get in contact easily with the animal reservoir,” says virologist Emmanuel Nakouné, scientific director at the Pasteur Institute of Bangui, which in 2018 launched a program named Afripox with French investigators to better understand and fight monkeypox.

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 DRC and the CAR, is 10 times more lethal, yet despite the relatively high disease burden in the DRC, it has never left Africa. But it has never caused a serious outbreak in a Congolese city either, which underscores the isolation of the areas where it is endemic. “It’s kind of a self-quarantine,” Mbala says. “Those people don’t move from DRC to other countries.”

Spilling over

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

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

Just where the current outbreak started, and how long ago, is unclear. “It’s a little bit like we’ve tuned into a new TV series and we don’t know which episode we’ve landed on,” says Anne Rimoin, an epidemiologist at the University of California, Los Angeles, who has worked on monkeypox in the DRC for 20 years. The first patient with an identified case traveled from Nigeria to the United Kingdom on 4 May, 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 recently traveled to Africa as well, and perhaps imported the virus separately. But none of the other cases identified in recent weeks has links to infected travelers or animals from endemic countries. Instead, many early 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, Africa’s most populous country, which has good infrastructure connecting rural areas to large cities and two airports that are among the busiest in Africa. But this is “highly speculative,” stresses Christian Happi, who runs Nigeria’s African Centre of Excellence for Genomics of Infectious Diseases. Happi urges people in other countries “not to point fingers,” but to collaborate.

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

Virus 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.

Monkeypox is a new global threat. African scientists know what the world is up against
(Graphic) K. Franklin/Science; (Data) E.M. Bunge et al., PLOS Neglected Tropical Diseases, 16(2): e0010141 (2022)

African countries’ ability to deal with monkeypox was improving even before the current outbreak. The DRC has stepped up its surveillance across the vast country, which is key to isolating infected people and tracking the virus’ moves. INRB and a lab in Goma can now diagnose samples using the polymerase chain reaction assay, and researchers ultimately hope to develop rapid tests for use in clinics nationwide. INRB and labs in Nigeria can also sequence the full genome of the virus, and Nigeria plans to make public genomes of several recent monkeypox isolates, 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, Africa lacks medicines to prevent and treat monkeypox. In the United Kingdom and the United States, high-risk contacts of cases are being offered a vaccine produced by Bavarian Nordic that was approved for monkeypox by the U.S. Food and Drug Administration in 2019, but it’s not available anywhere in Africa. The U.S. Centers for Disease Control and Prevention and collaborators in the DRC are testing the vaccine in health care workers; the 2019 approval was based on animal studies.

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

Although the international outbreak has—again—highlighted global health inequities, it has also brought much-needed attention to the smoldering disease in Africa. “It’s been really hard to get the resources to do the kind of background work that really needs to be done and that isn’t hair-on-fire, in the context of an emergency,” Rimoin says. “We cannot keep hitting the snooze button. Now, the stakes are really high.”

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