As the smallpox of the monkey feeds fears again in a world tired of the pandemic, some researchers in Africa have their own feeling of déjà vu. Another neglected tropical disease of the poor only draws attention after it begins to infect people in rich countries. “It’s like your neighbor’s house is burning and you close the window and say it’s okay,” said Yap Boum, a Cameroonian epidemiologist who works with both the health ministry and Médecins Sans Frontières.
Now, the fire is spreading. The global outbreak of monkeypox, which causes smallpox-like skin lesions but is not usually fatal, arose on May 7 in the UK. As of May 31, more than 700 suspected and confirmed cases had been reported from all continents except Antarctica. It is the largest outbreak in history outside of Africa and is concentrated among men who have sex with men, a phenomenon never seen before. Public health officials and scientists are struggling 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’re interdependent,” Boum points out. “What is happening in Africa will certainly affect what is happening in the West and vice versa.”
Smallpox 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 the largest burden, by far, with 1,284 cases in 2022 alone. These figures are almost certainly underestimated. In the DRC, infections occur more frequently 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 from a wild monkey in Africa. once. It seems to be more common in species of squirrels, rats and shrews, occasionally pouring into the human population, where it spreads mainly by close contact, but not by respiration. Isolating infected people usually helps the outbreaks to end quickly.
Cases have steadily increased in sub-Saharan Africa over the past 3 decades, driven largely by a medical triumph. The smallpox vaccine, a much more deadly and transmissible virus, also protects against smallpox, but the world stopped using it in the 1970s, shortly before smallpox was declared eradicated. As a result, “There are a large 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). Kinshasa, DRC.
Mbala says demographic changes have also fueled the rise. “People are moving more and more into the forest to find food and build houses, and this increases the contact between wildlife and the population,” he says. Studies at the CAR showed that the number of cases increased after the villagers moved to the forest during the rainy season to collect caterpillars that are sold for food. “When they stay in the bush they easily come into contact with the animal reservoir,” says virologist Emmanuel Nakouné, scientific director of the Pasteur Institute in Bangui, who in 2018 launched a program called Afripox with French researchers to understand and better fight the smallpox of the monkey.
Outbreaks outside of Africa, including the current one, have all involved the West African strain, which kills around 1% of those infected. The Congo Basin strain, which is found in the DRC and the Central African Republic, is 10 times more lethal, but despite the relatively high disease burden in the DRC, it has never left Africa. But it has also never caused a serious outbreak in a Congolese city, which highlights the isolation of 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.”
Pouring
The monkeypox virus infects squirrel, rat and shrew species in at least 10 countries in West and Central Africa and occasionally infects the human population. So far this year, five countries have reported human cases.
(Chart) K. Franklin / Science; (Data) World Health Organization
It is unclear where the current outbreak 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 got into,” 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 diagnosed later, 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 have links to infected travelers or animals from endemic countries. In contrast, many of the early cases were related to transmission to gay festivals and saunas in Spain, Belgium, and Canada.
Some suspect that the virus may have been imported from Nigeria, the most populous country in Africa, which has a good infrastructure that connects rural areas with large cities and two airports that are among the busiest in Africa. But that is “highly speculative,” said Christian Happi, who heads Nigeria’s African Center of Excellence for the Genomics of Infectious Diseases. Happi urges people in other countries “not to point the finger,” but to cooperate.
Epidemiologist Ifedayo Adetifa, head of Nigeria’s Disease Control Center, says the country is receiving undue attention because it is more vigilant than its neighbors and shares what it finds. “There is too much emphasis for any reason in Western capitals and the media on trying to hold responsible for a particular outbreak,” he says. “We don’t think these stories are useful.” Adetifa says that while Nigeria has recently seen “an increase in cases”, it is confident that a large number will not be lost. “We’re literally ringing the bushes to see what comes out.”
Virus on the rise
In the 4 decades since the world stopped smallpox vaccination, suspected and confirmed cases of smallpox in Africa have steadily increased.
(Chart) K. Franklin / Science; (Data) EM Bunge et al., PLOS Neglected Tropical Diseases, 16 (2): e0010141 (2022)
The ability of African countries to cope with smallpox was improving even before the current outbreak. The DRC has stepped up its surveillance across the large country, which is key to isolating infected people and tracking virus movements. The INRB and a Rubber Lab can now diagnose samples by polymerase chain reaction testing, and researchers are finally hoping to develop rapid tests for use in clinics across the country. The INRB and Nigerian laboratories can also sequence the entire genome of the virus, and Nigeria plans to make public the genomes of several recent smallpox isolates, according to Adetifa. These and other African sequences could help researchers identify the source of the international outbreak by building viral family trees.
At present, Africa has no drugs to prevent and treat monkeypox. In the United Kingdom and the United States, high-risk contacts are offered a vaccine produced by Bavarian Nordic that was approved for monkeypox by the U.S. Food and Drug Administration in 2019, but not available anywhere in Africa. The U.S. Centers for Disease Control and Prevention and DRC collaborators are testing the vaccine on health care workers; the 2019 approval was based on animal studies.
At the CAR, 14 people with monkeypox have received an experimental drug, tecovirimat, as part of a trial launched by Oxford University in July 2021. “We have had very good results,” says Nakouné, who ensures that it is waiting for the data. which will be published in the coming weeks. The manufacturer of the drug, SIGA, has promised to offer up to 500 courses of treatment in the country.
While the international epidemic has once again highlighted global health inequalities, it has also drawn much-needed attention to the disease that is being smoked in Africa. “It has been very difficult to get the resources to do the kind of background work that really needs to be done and that is not a hair in the fire, in the context of an emergency,” Rimoin says. “We can’t keep pressing the repeat button. Now the bet is very high.”