Health

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

As monkeypox stokes fears of the back-and-forth in a pandemic-weary world, some researchers in Africa are having their own sense of deja vu. Another neglected tropical disease of the poor only gains attention after it begins to infect people in rich countries. “It’s like your neighbor’s house is on fire and you just close your window and say everything is fine,” says Yap Boum, an epidemiologist in Cameroon who works with both the Ministry of Health and Doctors Without Borders. .

Now the fire is spreading. The global outbreak of monkeypox, which causes smallpox-like skin lesions but is not usually fatal, surfaced on May 7 in the UK. More than 700 suspected and confirmed cases had been reported as of May 31, on all continents other than Antarctica. This is the largest outbreak ever seen outside of Africa and it 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’re paying new attention to Africa’s long experience with the disease.

“We are interdependent,” notes Boom. “What happens in Africa will definitely impact what happens 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 Congo (DRC) has by far the highest burden, with 1,284 cases in 2022 alone. These numbers are almost certainly an underestimate. In the DRC, infections most often occur in remote rural areas; in the CAR, armed conflict in several regions has limited oversight.

The virus gets its name after it was first identified in a colony of Asian monkeys in a laboratory in Copenhagen, Denmark, in 1958, but was isolated only once from a wild monkey, in Africa. . It appears to be most common in squirrel, rat, and shrew species, occasionally spilling over into the human population, where it is spread primarily through close contact, but not through respiration. Isolating infected people generally helps end outbreaks quickly.

Cases have steadily increased in sub-Saharan Africa over the past 3 decades, largely due to medical triumph. The vaccine against smallpox, a much 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 is 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 for Biomedical Research (INRB) in Kinshasa, DRC. .

Mbala says demographic changes have also fueled the rise. “People are increasingly moving into the forest to find food and build homes, which increases contact between wildlife and people,” he says. Studies in CAR have shown that cases increase after villagers move into 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 reservoir,” explains virologist Emmanuel Nakouné, scientific director of the Pasteur Institute in Bangui, which launched a program called Afripox in 2018 with French researchers to better understand and combat 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, present in the DRC and CAR, is 10 times more deadly, but despite the relatively high disease burden in the DRC, it has never left Africa. But it has never caused a serious epidemic in a Congolese city either, which underlines the isolation of the areas where it is endemic. “It’s a kind of self-quarantine,” Mbala says. “These people are not moving from the DRC to other countries.

Overflow

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.

map of african countries with cases of monkeypox
(Graphic) K.Franklin/Science; (Data) World Health Organization

It is unclear exactly where the current outbreak began and for how long. “It’s a bit like we’re listening to a new TV series and we don’t know which episode we 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 UK on May 4, but does not appear to have infected anyone else. Two patients later diagnosed, one in the United States and the other in the United Arab Emirates, had also recently traveled to Africa and may have imported the virus separately. But none of the other cases identified in recent weeks are linked to travelers or infected 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 linking rural areas to major cities and two of Africa’s busiest airports. But that’s “highly speculative,” said Christian Happi, who heads the Nigerian African Center 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 Center for Disease Control, says the country is getting excessive attention because it does more surveillance than its neighbors and shares what it finds. “There is too much emphasis for any reason in Western capitals and the news media about trying to hold someone accountable for a particular outbreak,” he says. “We don’t think these stories are helpful.” Adetifa says that although Nigeria has recently seen “an increase in the number of cases”, he is confident that it is not missing a large number. “We are literally shaking 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.

(Graphic) K.Franklin/Science; (Data) EM Bunge et al., PLOS Neglected Tropical Diseases16(2): e0010141 (2022)

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

For now, Africa lacks drugs to prevent and treat monkeypox. In the UK and US, high-risk contacts of cases are being offered a vaccine produced by Bavarian Nordic which was approved for monkeypox by the US Food and Drug Administration in 2019, but it is not is available anywhere in Africa. The US Centers for Disease Control and Prevention and collaborators in the DRC are testing the vaccine on health workers; the 2019 approval was based on animal studies.

In CAR, 14 people with monkeypox received an experimental drug, tecovirimat, in a trial launched by Oxford University in July 2021. “We had very good results,” says Nakouné, who said to expect the data to appear in the coming weeks. The drug’s manufacturer, SIGA, has pledged to provide up to 500 treatments in the country.

While the international epidemic has once again brought into sharp focus the inequities in global health, it has also drawn much-needed attention to the disease smoldering in Africa. “It’s been really difficult to get the resources to do the kind of groundwork that really needs to be done and isn’t very hot, in the context of an emergency,” Rimoin says. “We can’t keep hitting the snooze button. Now the stakes are really high.

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