Genetic data point to at least two separate outbreaks of monkeypox, suggesting further spread


Genetic data point to at least two separate outbreaks of monkeypox, suggesting further spread

TThe Centers for Disease Control and Prevention said Friday that new genetic sequencing data suggests at least two separate monkeypox outbreaks are underway outside of Africa — a surprising finding that an official said the international spread is wider and longer than before recognized occurrence.

Three out of 10 viruses the CDC has sequenced from recent cases of monkeypox in the United States — two from 2021 and eight from 2022 — are different from the viruses sequenced from several countries involved in the major outbreak are involved, which is spreading in and from Europe. This outbreak is currently being driven by infections among gay, bisexual and other men who have sex with men.

While the three distinct viruses are clearly related and share a common ancestor, they are also more distinct from each other than the other viruses, Inger Damon, director of the CDC Division of Pathogens and High Consequence Pathology, told STAT in an interview.


The people infected in those three cases have contracted the virus from a surprising number of locations – one in Nigeria, one elsewhere in West Africa and the third in either the Middle East or East Africa. This apparently widespread distribution of a related virus — one distinct from the European outbreak strain — suggests that monkeypox outbreaks outside of countries where the virus is thought to be endemic may have simmered longer than previously thought, Damon acknowledged.

“I think that’s a very plausible explanation,” she said.


“We believe this indicates that there have likely been multiple introductions from Nigeria in the recent past and that additional transmission events are likely to occur globally,” Damon said.

“It begs the question… are there reservoirs and human infections occurring over a larger area? And I think it’s really a wider understanding of the Middle East and East Africa as potential areas where the virus has been introduced.”

Health officials have already raised concerns about stopping the spread of monkeypox, with Hans Kluge, the director of the World Health Organisation’s European office, acknowledging earlier this week that it is currently unclear whether the outbreak will be contained.

When asked if she thought the spread of monkeypox could be stopped, Damon dodged the question.

“Everyone is working really hard trying to understand what’s happening and … thinking about what public health tools can be used to prevent further spread, including looking at the use of vaccines and the use of therapeutics that are.” are not available in unlimited supply,” she said. “I think just with the close monitoring and looking at what’s happening, we’ll understand if this is something that can be contained.”

The CDC previously uploaded four genetic sequences from 2022 US cases to an internationally shared database. As of Thursday, 21 cases have been reported from 11 states since the current outbreak became known.

On Friday, the CDC uploaded four more sequences from that year, plus two from independent introductions that took place in 2021. Those cases of 2021, detected in July and November, were people who had traveled to Nigeria and returned to Texas and Maryland, respectively.

All recent US cases were infected with the West African monkeypox clade, which is also responsible for the European outbreak. The West African group causes a milder disease than the Congo Basin group, which has been shown to kill up to one in 10 infected people in the Central African countries where it is found. The West African group has a lower mortality rate, estimated at around 1%. No deaths have been reported outside of Africa this year.

Since mid-May, when health officials in the UK alerted the world to the transmission of monkeypox in that country, some 40 countries in Europe, America, the Middle East and Australia have reported nearly 800 confirmed cases.

Damon said the seven other viruses the CDC has sequenced are very similar to the viruses that scientists have published in Europe. “These really cluster so tightly that we really think they’re all linked to the same outbreak,” she said.

Damon said the new findings suggest medical professionals should keep monkeypox in mind when confronted with patients who have unusual sores or a sexually transmitted infection.

“If you see an unusual rash disease or see something that looks like an STD to you, looks like syphilis, looks like herpes, we probably need to think about testing for monkeypox,” she said.

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