The monkeypox outbreak that health authorities first noticed in Europe in May is getting worse. According to the latest report from the World Health Organization, there are more than 2,100 confirmed cases and at least one person has died.
Now geneticists finally have enough data to begin to understand exactly how the outbreak started and where it might be headed.
It is not good news. Monkeypox, a viral disease that causes fever and rash and can be fatal in a small percentage of cases, is endemic in Africa. And now it’s unleashed on all other permanently inhabited continents and changing rapidly. While health officials have all the tools they need to contain it, primarily contact tracing and vaccines, the virus is currently moving faster than us and adapting.
The current strain of monkeypox may have been circulating, undetected, month before finally diagnosing the first case outside of Africa. And because there are so many more copies of the virus than expected, each mutated separately, this new strain of smallpox could be evolving into dangerous new forms at an alarming rate.
“Our data reveal additional clues about ongoing viral evolution and potential human adaptation,” wrote a team led by Joana Isidro, a geneticist at the National Institute of Health, Dr. Ricardo Jorge in Spain, in the new peer-reviewed study published Friday in natural medicine.
Monkeypox jumped from apes or rodents to humans in the Democratic Republic of Congo in 1970 and broke out frequently in Africa in the decades that followed. There are two main strains, one in West Africa and one in Central Africa. The milder West African strain can be fatal in up to 1% of cases. The most dangerous Central African strain can kill up to 10% of the people it infects.
Smallpox is mainly spread by close physical contact, especially sexual contact. This is not a sexually transmitted disease, however. He’s just enjoying the skin-to-skin contact that comes with sex. The virus can also travel short distances with spit, but probably not far enough to qualify as “airborne.”
Monkeypox sometimes spreads to places where it is not already endemic. In 2003, 47 people in the United States fell ill with the West African strain after being exposed to a shipment of pet rodents from Ghana to Texas. A quick response from state and federal health authorities — and a few doses of the smallpox vaccine, which also works on monkeypox — prevented anyone from dying and temporarily eliminated the virus in the United States.
“Because there are so many more copies of the virus than expected, each mutated separately, this new strain of smallpox could evolve into dangerous new forms at an alarming rate.”
Officials first noticed the current outbreak, also of the West African strain, after diagnosing a British traveler returning from Nigeria in early May. While hitchhiking in Europe, the virus spread rapidly through physical contact. David Heymann, who previously headed the World Health Organization’s emergency department, said men attending raves in Spain and Belgium had “amplified” the outbreak, apparently through close, sometimes sexual, contact. with other men.
After that, the virus accompanied travelers on planes to distant countries. Doctors diagnosed the first US case on May 27. As of Thursday, the US Centers for Disease Control had tallied about 3,500 cases in 44 countries, including 172 in the United States.
Only one person has died of smallpox in the current outbreak, in Nigeria. But serious illness and death can delay an actual diagnosis for weeks, so many more deaths may occur.
Worse still, on June 3, the CDC announced that it had found genetic evidence of smallpox cases in the United States that preceded the first cases in Europe from May. Doctors may not have noticed or reported these earlier cases, at first, due to the similarity between the symptoms of smallpox and the symptoms of some common sexually transmitted diseases such as herpes.
There was speculation that the earlier US cases were part of an entirely separate outbreak that overlapped with the outbreak in May. Isidro and his team sequenced 15 samples taken from current smallpox patients and concluded that no, there was only one large outbreak. “All epidemic MPX strains sequenced so far cluster closely, suggesting that the ongoing outbreak has a single origin,” they wrote, using the scientific acronym monkeypox.
It’s less clear exactly when the current epidemic has really begun. According to Isidro and company, the virus may have been circulating outside of endemic countries long before authorities finally noticed the infections and sounded the alarm. The virus potentially traveled beyond Africa in animals such as pet rodents and spread from animal to animal before eventually jumping onto a human host and sparking the current outbreak somewhere. time before May, the geneticists wrote.
Most likely, however, monkeypox spread in the usual way from person to person – and recently, Isidro’s team concluded. “Current data points for a scenario of more than one introduction from a single origin, with superspreading events (e.g. saunas used for sexual encounters) and foreign travel likely triggering the rapid global spread.”
In other words, someone – or several people – touched an infected person in Africa, then flew to Europe or the United States and transmitted the virus to others through direct contact. The “single origin” is the infected human population in Africa. “More than one introduction” means multiple travelers contracted the same strain of smallpox and spread it beyond Africa at around the same time.
All that to say. May’s case in the UK was the first infection authorities noticed, but chances are it wasn’t the infection that started the outbreak.
“When you start looking for something, you find it.”
— Michael Wiley, University of Nebraska Medical Center
A particularly troubling possibility is that smallpox is often or even usually circulating to some extent in non-endemic countries, but we rarely notice this unless there is a sharp rise in infections that forces doctors to take a closer look at symptoms that could easily be mistaken for something else. Say, herpes. “When you start looking for something, you find it,” Michael Wiley, a public health expert at the University of Nebraska Medical Center who wasn’t involved in the new study, told The Daily Beast.
Either way, undetected or overlapping vectors of transmission are alarming, and not just because they could mean faster viral spread to more places before authorities hopefully eventually contain an epidemic. No, multiple introductions also represent an opportunity for a virus to mutate more or faster than usual.
When it comes to viral diseases, each infected person is a kind of living laboratory, a place where the virus can interact with the antibodies and T cells of the human immune system and develop countermeasures. The more we transmit smallpox in separate chains of transmission, the more likely the virus is to mutate along those vectors in a way that advantages that and it hurts we. For example, developing resistance to our vaccines and antibodies.
Isidro’s team found 50 single nucleotide polymorphisms, or SNPs, in the monkeypox strain causing the current outbreak. Each SNP is a change in the basic DNA of a particular organism. Fifty SNPs “is much more (about 6 to 12 times more) than you would expect,” the geneticists wrote. “Such a divergent branch could represent accelerated evolution.”
This does not mean that smallpox itself learns to evolve faster. It’s possible that the current outbreak reached some sort of critical genetic mass before we had a chance to intervene. More people infected means more possibilities for evolution, even if the individual mutation rate is the same.
“If I had to guess, I think we might see more drift in terms of the number of mutations just based on the size of the outbreak,” said James Lawler, an infectious disease expert and colleague of Wiley’s at the Medical Center in Wiley. the University of Nebraska. , told The Daily Beast. “Drift” is just a fancy term for “increase” in this context.
Monkeypox may have been hiding in plain sight long before we finally noticed it two months ago. Perhaps this strain of the virus was lucky and more than one traveler helped spread it outside of Africa almost simultaneously. Maybe it evolves faster because it gets smarter. More likely, it’s changing at its current rapid rate because there are so many more copies of the virus than expected, each mutating at every opportunity.
It’s all bad news, regardless — and it should stoke an even greater sense of urgency among health officials as they scramble to diagnose and contain a growing number of cases.