The monkeypox outbreak that health authorities first noticed in Europe in May is getting worse. According to the latest World Health Organization report, there are more than 2,100 confirmed cases and at least one person has died.
Now geneticists finally have enough data to get to know exactly how the outbreak started and where it could go.
Not good news. Smallpox, 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 doing badly on every other permanently inhabited continent, and it’s evolving rapidly. While health officials have all the tools needed to contain it, mostly contact tracking and vaccines, right now the virus is moving faster than us and is adapting.
The current smallpox strain of the monkey may have been circulating, undetected, months before we finally diagnosed the first case outside Africa. And because there are many more copies of the virus than we expected, each mutant separately, this new smallpox strain could evolve into dangerous new forms at a disruptive rate.
“Our data reveal additional clues about ongoing viral evolution and possible human adaptation,” wrote a team led by Joana Isidro, a geneticist at the National Institutes of Health Dr. Ricardo Jorge in Spain, in the new peer-reviewed study published Friday in Nature. Medicine.
A medical lab technician is preparing to test suspicious smallpox samples in the microbiology lab at La Paz Hospital.
Pablo Blazquez Dominguez / Getty
Monkeypox first made the leap from monkeys or rodents to people in the Democratic Republic of the Congo in 1970, and has erupted frequently in Africa in later decades. There are two main strains, one in West Africa and one in Central Africa. The lightest strain in West Africa can be fatal in up to 1 percent of cases. The most dangerous Central African strain can kill up to 10 percent of people it infects.
Smallpox is spread mainly by close physical contact, especially by sexual contact. However, it is not a sexually transmitted disease. It only takes advantage of the skin-to-skin contact that accompanies sex. The virus can also travel short distances with saliva, although probably not far enough to qualify as “airborne.”
Smallpox is occasionally spread to places where it is not yet endemic. In 2003, 47 people in the United States fell ill with the West African strain after exposing themselves to a shipment of pet rodents from Ghana to Texas. A quick response from state and federal health officials, and a few doses of smallpox vaccine, which also works with monkeypox, prevented anyone from dying and temporarily wiped out the virus in the U.S.
“Because there are so many more copies of the virus than we expected, each mutant separately, this new smallpox strain could evolve into dangerous new forms at a disruptive rate.”
Officials first noticed the current outbreak, also of the West African stump, after diagnosing a UK traveler returning from Nigeria in early May. Upon reaching Europe, the virus spread rapidly through physical contact. David Heymann, who previously headed the World Health Organization’s emergency department, said men attending radishes in Spain and Belgium “amplified” the outbreak, apparently through close, sometimes sexual contact. , with other men.
After that, the virus accompanied travelers on planes heading to countries everywhere. Doctors diagnosed the first American case on May 27th. As of Thursday, the U.S. Centers for Disease Control had counted about 3,500 cases in 44 countries, including 172 in the U.S.
Only one person has died of smallpox in the current outbreak: in Nigeria. But serious illness and death can delay an actual diagnosis by several weeks, so there may be many more deaths.
Worse, on June 3, the CDC announced that it had found genetic evidence of smallpox cases in the United States prior to the first cases in Europe since May. Doctors may not have noticed or reported these previous cases, at first, because of the similarity between the symptoms of smallpox and the symptoms of some common sexually transmitted diseases such as herpes.
It was speculated that previous U.S. cases were part of a completely separate outbreak that overlapped with the May outbreak. Isidro and his team sequenced 15 samples taken from current smallpox patients and concluded that, no, there is only one large outbreak. “All the MPX strains of the outbreak sequenced so far are closely grouped together, suggesting that the ongoing outbreak has a single origin,” they wrote, using the scientific acronym for monkeypox.
A passenger walks in front of monkeypox virus information at Soekarno-Hatta International Airport in Tangerang, near Jakarta, Indonesia.
Jepayona Delita / Getty
It is unclear exactly when the current outbreak actually began. According to Isidro and the company, the virus could have been circulating outside endemic countries long before officials finally noticed the infections and sounded the alarm. The geneticists wrote that the virus traveled beyond Africa in animals such as pet rodents and spread from animal to animal before finally jumping on a human host and triggering the current outbreak some time before May.
Most likely, however, the monkey’s smallpox 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 source, with supercharging events (e.g., saunas used for sexual encounters) and trips abroad likely triggering rapid global diffusion” .
In other words, someone (or several people) touched an infected person in Africa, then flew home to Europe or the United States and spread the virus to other people through direct contact. The “only source” is the infected human population in Africa. “More than one presentation” means that several travelers took the same smallpox strain and spread it beyond Africa at the same time.
All that is to say. May’s case in the UK was the first to be noticed by infection authorities, but it was probably not the infection that started the outbreak.
“When you start looking for something, you find it.”
– Michael Wiley, University of Nebraska Medical Center
A particularly worrying possibility is that smallpox circulates often or even normally to some extent in non-endemic countries, but we rarely notice it unless there is a large increase in infections that forces doctors to look more closely at the smallpox. symptoms that can easily be confused with something. something else. For example, herpes. “When you start looking for something, you find it,” Michael Wiley, a public health expert at the University of Nebraska Medical Center who did not participate in the new study, told The Daily Beast.
In any case, undetected or overlapping transmission vectors are alarming, and not just because they could mean faster viral spread to more places before authorities finally, hopefully, contain an outbreak. No, multiple introductions also represent an opportunity for a virus to mutate more, or faster, than usual.
When it comes to viral diseases, every infected person is a kind of living laboratory, a place where the virus can interact with antibodies and T cells in the human immune system and develop countermeasures. The more separate transmission chains we deliver smallpox, the more likely it is that the virus will mutate along these vectors in some way that benefits and harms us. For example, developing resistance to our vaccines and antibodies.
Isidro’s team found 50 single-nucleotide polymorphisms, or SNPs, in the monkey’s smallpox strain behind the current outbreak. Each SNP is a change in the basal DNA of a particular organism. Fifty SNPs “are much more (about 6 to 12 times more) than one might expect,” the geneticists wrote. “Such a divergent branch could represent an accelerated evolution.”
This is not to say that smallpox itself is learning to evolve faster. It is possible that the current outbreak has just reached a kind of critical genetic mass before we have a chance to intervene. More infected people means more opportunities to evolve, even if the individual mutation rate is the same.
“If I had to guess, I think we can see more drift in terms of number of mutations just based on the size of the outbreak,” James Lawler, an infectious disease expert and Wiley’s colleague at the University of Nebraska Medical Center . , he told The Daily Beast. “Drift” is just a fantastic term for “increase,” in this context.
Maybe the monkey’s smallpox would have been hidden from view long before we finally realized it two months ago. Perhaps this strain of the virus was lucky and more than one traveler helped spread it out of Africa almost simultaneously. Maybe he’s evolving faster because he’s getting smarter. You’re more likely to be switching to your current quick clip because there are many more copies of the virus than we expected at first, each mutating every chance you get.
All of this is bad news, independently, and should fuel an even greater sense of urgency among health officials as they strive to diagnose and contain a growing number of cases.