Scientists zero in on the source of the monkeypox outbreak

When the first monkeypox cases were detected in early May, European health officials were shocked. The virus was not known to spread easily among humans, dozens – and soon infected hundreds of young people.

The source of the outbreak is now becoming clear. Genetic analysis shows that although the monkeypox virus is spreading rapidly in public, it has been quietly spreading among humans for years.

Health officials have already identified two versions of the monkeypox in American patients, suggesting at least two separate chain infections. Researchers in several countries have found cases where there is no known source of infection, indicating the spread of undiagnosed communities. And a research team argued last month that monkeypox has already exceeded a threshold for person-to-person transmission.

Genetic information found so far Informed Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, says that at some point in the last few years, the virus has become better at spreading to humans.

“Genomic patterns would suggest that this happened in 2018,” Dr. Bedford said.

If the virus adapts to include people as hosts, the outbreak of monkeypox may become more frequent and more difficult to control. It carries the risk that monkeypox could spread from infected individuals to animals – possibly rats – in countries outside Africa, who have been battling the problem for decades. The virus can be present in infected animals, sparsely initiating new infections in humans.

“We can also send it back to animals that can spread the disease to wildlife and humans,” said Sagan Fryant, an anthropologist at Pennsylvania State University, who has been studying human-animal interactions in Nigeria for nearly 15 years.

The longer it takes for the virus to take hold, the more likely it is that humans or animals will find a permanent new home. Freent says.

As of Wednesday, the United States had identified 156 cases in 23 states and the District of Columbia. Worldwide tolls have surpassed 3,400 confirmed cases and another 3,500 cases are being assessed, tripling the number from two weeks ago.

In Africa, more than 1,500 suspected cases and 72 deaths have been reported in eight countries as of June 10, most of them in the Democratic Republic of Congo.

Monkeypox is a large double-stranded DNA virus, about seven times larger than the coronavirus. DNA-based viruses can correct their own defects when replicating their genetic material. They can collect only one or two mutations a year, compared to 20 to 30 mutations for an RNA virus, such as a coronavirus.

However, the monkeypox virus appears to have collected an unexpectedly high number of mutations – about 50 more than a version released in 2018, according to preliminary analysis.

Of the 47 mutations identified in one analysis, 42 bear the unique signature of an enzyme called Apobec3. The enzyme, first discovered by researchers studying HIV, is a so-called host defense factor – an immune-system weapon used by animals and humans to disarm viruses like monkeypox.

Enzymes basically force viruses to make mistakes when they try to replicate, resulting in their self-destruction. Rats carry only one version of this enzyme, while humans carry seven. Features of the enzyme since 2018, the rapid accumulation of mutations indicate that the monkeypox then changed to host people in the vicinity, Dr. Bedford says.

It is not clear how mutations can alter the virus. According to the UK Health Security Agency, of the 48 mutations identified in the UK, 21 could affect how the disease spreads, its severity and how well it responds to a treatment called tacovirimet.

But since the mutations introduced by the enzyme Apobec3 are meant to harm the virus, not only are their amounts alarming, says Michael Malim, a virologist at King’s College London who discovered Apobec3 in 2002. The effects of mutations are “more likely to be enabled,” he said. Comparing current versions of the virus with samples from the past few years may help explain how it evolved, but little is known about it. Nigeria did not have the ability to sequence genetic material until 2017. .

Since then, scientists have been analyzing the sequence of events in about 50 monkeypox, according to Dr. Ifedayo Adetifa, director of the Nigeria Center for Disease Control. But scientists have not yet been able to complete their work without the special tools or skills needed for rapid analysis, he said.

Although researchers have made several requests for data from outside Nigeria, Dr Adetifa said they would wait for their work to be published to prevent teams with more resources from competing with them and seizing credit.

“I’m open to sharing data and for all of this,” he said. “The question is, who benefits?”

Some experts have been warning for years that the eradication of smallpox in 1980 left the world vulnerable to a larger family of poxviruses and increased the chances of monkeypox developing into a successful human pathogen.

In West Africa, the incidence of monkeypox has increased at least twentyfold since 1986. In African countries in general, Dr. Adetifa said, “we suspect some less reporting because there was relatively less awareness and probably less perceived risk.” Nigeria is stepping up surveillance on monkeypox and the number of cases could increase as more people become aware of the virus, he added.

Although monkeypox has a distinct rash that can be seen on the palms of the hands and the soles of the feet, it is often confused with chickenpox. Many men with the current outbreak have genital sores, but they can be mistaken for sexually transmitted infections such as syphilis, gonorrhea and chlamydia.

Researchers in Italy and Germany have reported finding monkeypox DNA in semen, but it is unclear whether the virus spreads that way or is only present in semen and vaginal discharge.

It was seen at least once before it spread among young people with genital ulcers. In 2017, 228 suspected cases of monkeypox were recorded in Nigeria and 60 were confirmed. The virus initially spread to young men who had genital ulcers.

Experience in the UK shows how difficult it can be to identify a virus that can be sexually transmitted, especially in cases where infected people have multiple anonymous partners. In a preliminary analysis of a subset of cases, officials said they were able to get names for less than one-third of the 78 reported sexual encounters.

In many parts of Africa the use of animal products has been found in contact with wildlife or for medicinal or cultural practice.

As deforestation and urbanization bring humans and animals closer together, more viruses can spread to human hosts. Monkeys are most likely to jump from rats to humans. There are about 2,000 species of rats worldwide, making up 40 percent of all mammal species. The African rope squirrel is a leading candidate as the primary reservoir of the monkeypox, but there are other competitors, including striped rats and dormice, giant bagged rats, rusty-nosed rats, and brush-tailed porcupines.

During an outbreak in the United States in 2003, a consignment of Gambian pouched rats imported from Africa sent monkeypox to prairie dogs, which then infected 71 Americans. However, after the outbreak of the case, the authorities did not find any signs of the virus in the animals in the United States.

There is no guarantee that fate will hold this time. “These spillovers of other species, and what they mean and what the trajectory is – it’s very unexpected,” he said. Malim says 6 “And it’s happening more and more.”

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