The origin of the outbreak of monkeypox is revealed to scientists

European health officials were confused when the first case of monkeypox was identified in early May. The virus was not known to spread easily among people, much less to infect dozens, and even hundreds, of young men.

The cause of the outbreak is now becoming clear. Genetic analysis suggests that the monkeypox virus is rapidly spreading in the field, but has been quietly prevalent in people for many years.

Health officials have already identified two versions of monkeypox among American patients, suggesting at least two separate transmission routes. Researchers in several countries have found cases with no known source of infection. This shows the spread of undetected communities. And one research team last month claimed that monkeypox had already exceeded the limits of sustainable human-to-human transmission.

Genetic information available so far Shown Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, said that at some point in the past few years, the virus had become better spread among people.

“The genomic pattern suggests that this happened around 2018,” Dr. Bedford said.

If the virus is adapted to include humans as a host, monkeypox will occur more frequently and may be more difficult to contain. It carries the risk of spreading monkeypox from infected people to animals (probably rodents). Countries other than Africa have been suffering from the problem for decades. The virus can persist in infected animals and sporadically cause new infections in people.

Sagan Friant, an anthropologist at Pennsylvania State University, who has been studying human-animal interactions in Nigeria for almost 15 years, said:

The longer it takes to contain the virus, the more likely it is that humans and animals will find a permanent new home, Dr. Friant said.

As of Wednesday, the United States has identified 156 cases in 23 states and the District of Columbia. Global tolls have exceeded 3,400 confirmed cases, and an additional 3,500 cases have been evaluated, three times the number two weeks ago.

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

Monkeypox is a double-stranded DNA virus that is about seven times as large as the coronavirus. DNA-based viruses can correct their own errors when replicating genetic material. Compared to 20 to 30 mutations in RNA viruses such as coronavirus, they may collect only one or two mutations per year.

However, preliminary analysis suggests that the monkeypox virus has unexpectedly accumulated many mutations. It will be close to 50 compared to the version that was popular in 2018.

Of the 47 mutations identified in one analysis, 42 have distinct characteristics of an enzyme called Apobec3. This enzyme was first discovered by researchers studying HIV and is a so-called host defense factor. This is the weapon of the immune system that animals and people use to disarm viruses such as monkeypox.

Enzymes essentially make mistakes when the virus tries to replicate, causing the virus to self-destruct. Mice have only one version of this enzyme, while humans have seven. The rapid accumulation of mutations that is characteristic of enzymes since 2018 suggests that monkeypox may have switched to people as hosts at that time, Dr. Bedford said.

It is unclear how mutations change the virus. Of the 48 mutations identified in the United Kingdom, 21 can affect the spread, severity, and response to a treatment called tecovirimat, according to the UK Health and Safety Agency.

But the mutations introduced by the enzyme Apobec3 are intended to harm the virus, so don’t worry about the amount alone, says Michael Malim, a virologist at King’s College London, who discovered Apobec3 in 2002. I am. , “He said. Comparing the current version of the virus with samples from the last few years may help to understand how the virus has evolved, but there is little information about it in Nigeria. Was incapable of sequencing genetic material until 2017.

Since then, scientists have analyzed the sequence of about 50 monkeypox cases, according to Dr. Ifedayo Adettifa, director of the Nigerian Disease Control Center. But without the specialized equipment and expertise needed for rapid analysis, scientists have not yet completed their work, he said.

Researchers have submitted some requests for data from outside Nigeria, but Dr. Adettifa reveals their work to prevent teams with more resources from defeating them and gaining credit. I said I’d wait to do it.

“I’m all in favor of open data sharing and all of it,” he said. “The question is, who will benefit?”

Some experts said that the eradication of smallpox in 1980 made the world vulnerable to a wider family of poxviruses, increasing the likelihood that monkeypox would evolve into a successful human pathogen. I have warned that for many years.

In West Africa, the incidence of monkeypox has increased at least 20-fold since 1986. In African countries, Dr. Adettifa generally states that “underreporting is suspected because of the relatively low awareness of monkeypox and probably the low risk of monkeypox.” Nigeria has increased surveillance of monkeypox, he added, which could increase the number of cases as more people become aware of the virus.

Monkeypox has a unique rash that appears on the palms and soles of the feet, but is often confused with chickenpox. Many of the men who are currently affected have genital lesions, which can be mistaken for sexually transmitted diseases such as syphilis, gonorrhea, and chlamydia.

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

The spread of genital ulcers among young men was observed at least once. In 2017, Nigeria recorded 228 suspected monkeypox cases and confirmed 60 cases. The virus spread primarily to young men with genital ulcers.

UK experience shows how complex it is to track contact with a potentially sexually transmitted virus, especially if the infected person has multiple anonymous partners. In the initial analysis of a subset of cases, officials said they were able to obtain names for less than one-third of the 78 reported sexual contacts.

Many cases in Africa date back to contact with wildlife or the use of animal products for medical and cultural practices.

As deforestation and urbanization drive humans and animals closer together, more viruses can fly to human hosts. Monkeypox is most likely to leap to people from rodents. There are about 2,000 rodent species worldwide, accounting for 40 percent of all mammal species. The giant pouched rat is a strong candidate for a major reservoir for monkeypox, but there are other candidates such as striped rats and dormouses, giant pouched rats, rusty nose rats, and porcupines.

In the 2003 US outbreak, the shipment of Gambian bagged rats imported from Africa infected monkeypox with prairie dogs and 71 Americans. However, after a series of incidents, authorities did not find any signs of the virus in US animals.

There is no guarantee that luck will continue this time. “These spillover effects from other species, and what they mean and what the orbit is-it’s very unpredictable,” Dr. Marim said. “And it’s happening more and more.”

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