Studies show that monkeypox is not susceptible to infection from respiratory droplets or contaminated objects. That’s one of the reasons the virus hasn’t spread more widely in the US
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Studies show that monkeypox is not susceptible to infection from respiratory droplets or contaminated objects. That’s one of the reasons the virus hasn’t spread more widely in the US
AP
Just a few months ago, it seemed that the United States had lost its chance to eliminate the spread of monkeypox – that is, to stamp out the outbreak and reduce the number of cases to zero, excluding new infections coming from abroad. .
Experts worry it is only a matter of time before the virus begins to spread more widely in the US, especially in places like daycare centers and college dormitories.
It is now clear that those fears have not materialized. Some infectious disease experts have even floated the idea that the US could get rid of the virus.
Cases of monkeypox have down since peak in early August – from 440 cases per day, down to 60 cases – and this is the lowest level since June. The virus has continued to circulate almost entirely in gay and gay sex networks. And the supply of vaccines is abundant, even far beyond current needs.
“Where we are right now is the best case scenario, in terms of what can happen when you actually use the tools you have to fight the outbreak,” Dr. Boghuma Titanjian infectious disease specialist at Emory University.
So what changed the trajectory?
Health experts attribute the success to changes in the behavior of people at high risk of monkeypox and the rapid absorption of the vaccine. But more and more evidence shows that again factor also helps slow the outbreak: the virus can only be spread under very specific circumstances.
Monkeypox is not likely to be spread through saliva and surfaces
Initially, there was a great deal of concern that monkeypox could be widespread in daycares or schools, but overall, there is little transmission among children.
Only about 0.2% of cases in the US have occurred in children under 16 years of age. And, to date, there is no evidence that a sick child or teacher has spread the virus to others at a school or daycare. (Universities are a separate issue. Some schools have reported cases in students, but none have reported large outbreaks, at this time.)
With children, concern comes from understanding that Viruses can spread through saliva – which means it can be spread when you look up close to someone’s face while talking or coughing. Smallpox in monkeys can also be spread when a person touches someone’s contaminated objects and surfaces. But in practice, it is very rare to catch smallpox in monkeys either way.
Some studies have found that there is usually not much virus in the upper respiratory tract. Instead, the highest levels of the virus occur on sores on the skin and inside the anus.
In one of the learn, researchers at the Israel Institute of Biological Research measured virus levels in 44 monkeypox patients. They took samples from the patients’ skin wounds and their throat swabs. They found that skin wounds contained, on average, 17 times more infectious viral particles than swabs from the throat.
Another study, published Last month, similar results were obtained, but these researchers went further: they also analyzed levels of viral DNA in the patients’ blood, urine, semen and swabs from the anus, in addition to samples taken from the skin and throat. Although high levels of monkeypox DNA showed up in the throats and semen of some people, those samples contained much less virus on average than samples from anus or skin wounds. Urine and blood have the lowest viral load.
Together with some previous research, these newer findings explain why monkeypox is spread almost exclusively through sexual contact, especially anal and oral sex. , in the current outbreak.
Even during sex, monkeypox only causes outbreaks in specific cases
But the study still doesn’t explain why the disease isn’t widely spread among women who are also sexually active.
Since the start of the outbreak in the US, CDC data shows that the majority of cases have remained in men. Infection rates are also very high among transgender men and women. Meanwhile, only about 2% of cases occur in women.
As it turned out, it wasn’t just sex but an outbreak of smallpox in monkeys.
In one study, published last month in the magazine Science, the researchers found that monkeypox spreads at very different rates in different groups of people — and that rate depends a lot on people’s sexual activity. Researchers from Nagasaki University and the London School of Hygiene & Tropical Medicine have built a mathematical model of the global outbreak. They then looked at how the number of sexual partners changed the transmission of smallpox in monkeys in their network. In general, monkeypox outbreaks are highly likely to occur in only one particular type of sexual network: where a small number of people have a high number of sexual partners.
Also, outbreaks of monkeypox are very rare. Research shows that chains of transmission almost always stop on their own because the chance of one person spreading the virus to another is low.
During the US outbreak, monkeypox “was actually included in a core group of sexually active men who had sex with multiple partners,” Dr. . Jeffrey Klausner, a professor of medicine and public health at the University of Southern California, who was not involved in the study. And in this group, some are at higher risk: “It’s not the long-term monogamous relationships, or the men who occasionally have an extra partner every few months… to be [concentrated among] Men have many new sex partners every week. “
And as people in these active sex networks gain immunity to monkeypox – either by recovering from the infections or by getting vaccinated – the number of people suspected of being infected is dropping. .
Can monkeypox be eliminated in the US?
Some say it is possible to stop the chain of monkeypox transmission in the US and reduce the number of cases to near zero (at least, not counting cases that will come from other parts of the world where the virus is still present). spreading).
“I think we can expect to see regional elimination, potentially nationwide elimination, where we won’t see some lingering cases,” said Klausner, who pointed to found that in some large cities, including San Francisco, Chicago and New Yorkonly a few cases are detected per day.
However, new infections have not fallen evenly across all cities, and the rate of infections among men of color is increasing.
In fact, CDC data shows that monkeypox cases are significantly reduced in white males, but nearly 70% of cases are now detected in Black or Latino men. Health officials have acknowledged that these populations are being vaccinated at a lower rate than white men.
And not all experts are optimistic about eliminating the virus in the country.
There are still important unknowns that could affect the trajectory of the outbreak, such as whether asymptomatic (or mildly symptomatic) people unknowingly spread monkeypox and the vaccine. how effective it is – both in preventing infection and transmission of smallpox in monkeys. “Do they offer 100%, 75% or 50% protection?” Titanji said. “And is that protection for the rest of your life? Or will you need follow-up vaccinations to maintain that level of protection?”
These are open-ended questions.
Then there’s the virus itself and how it can change. Can it gain a foothold in animal populations in the US or Europe and establish a long-term reservoir for the virus? Or maybe it mutant in ways could that increase its infectivity to humans?
“These are factors that are likely to affect whether we can get rid of this virus and go back to the way it was,” Titanji said, “So the jury is still out. no results”.
However, monkeypox may not need to be completely eliminated in the United States for it to cease to be a national public health emergency. As cases decline in major cities, outbreaks may be more limited and local.
If that happens, the challenge will be to ensure it doesn’t “become another neglected sexually transmitted infection, joining the ranks of gonorhea, chlamydia and syphilis,” Titanji said. These are all preventable diseases, but they still cause long-term health problems for many people, especially in historically marginalized communities.
