Cases of monkeypox continue to climb across the globe, with more than 200 confirmed and suspected cases documented in over 20 countries. Scientists are starting to gather their first clues about these outbreaks, including how the virus may have begun spreading farther than it ever has before.
According to a tracker from the group Global.health, there have been 174 confirmed and 93 suspected cases reported from 21 countries as of Tuesday afternoon. The UK and Spain have reported the most cases, and at least seven cases have been found in the U.S., including one in New York City. No deaths are reported so far; the type of monkeypox virus associated with these cases is known to have a fatality rate around 1%.
The viral disease tends to cause large bumpy rashes throughout the body, along with flu-like symptoms. It can take up to three weeks following exposure for symptoms to start and two weeks for the illness to clear. The virus primarily spreads through direct contact, though it may also be spread through contaminated surfaces as well as respiratory droplets and aerosols. Infected people aren’t considered contagious until after they start showing symptoms.
Monkeypox, closely related to the now-extinct smallpox virus, is endemic to parts of Africa and is thought to typically infect rodents. Following its discovery in the 1950s, it has occasionally jumped from animals to humans, causing localized outbreaks with limited transmission between humans. That makes these newest cases far different from past incursions of the virus. But we may have some early indications of what’s going on.
Some researchers have been able to genetically sequence samples of the virus collected from patients. These results suggest that the strains in these cases are closely related to strains recently collected from Nigeria, where outbreaks have been ongoing since 2018. So far at least, there doesn’t seem to be evidence that the virus has mutated in any significant way since then, which is reassuring. But further research will be needed to rule out the possibility that it somehow became more inherently transmissible between humans.
“In the past, human to human spread has occurred but has been quite limited. We don’t know that it is spreading more easily from person to person yet. That is one possible explanation, but I am not aware of any evidence to support that idea yet,” Andrew Pavia, an infectious disease doctor at the University of Utah, told Gizmodo last week.
If the virus hasn’t changed intrinsically, then these outbreaks may be the result of other factors, including how it’s now being caught. Many cases have been found in young gay and bisexual men who were recently sexually active. And a World Health Organization adviser has argued that its spread may have been amplified by two recent raves in Spain and Belgium where casual sex was common.
Even if this does turn out to be true, though, it wouldn’t mean that gay or bisexual men are the only people at risk, since the virus can spread through direct contact between any sexual partners. It’s also possible that these cases were first found simply because these individuals tend to be more cognizant about the risk of sexually transmitted infections in general and are more likely to regularly see a doctor as a result. On Tuesday, popular dating app Grindr sent out an alert about monkeypox to its users, advising them to seek medical help if they or a recent sexual partner develop unusual sores or rashes.
Other experts have argued that the virus may be spreading more now because of declining immunity to the related smallpox virus, following its eradication in 1980. Poxviruses often cause cross-immunity to other poxviruses, but this protection has faded over time in the general population for various reasons, according to Jo Walker, an infectious disease epidemiologist and modeler at the Yale School of Public Health.
“This ‘declining immunity’ is less due to waning immunity at the individual level, and more due to people with immunity dying, and people without immunity being born and then staying non-immune,” Walker told Gizmodo last week.
The risk of monkeypox to the general public is still considered to be low. And for now, Pavia says, there is no reason to panic or for most people to have any worries. “But it is early days, so that may change,” he noted.
Indeed, health officials in Europe have warned that if these outbreaks aren’t contained quickly and effectively enough, the virus could establish itself in new parts of the world and regularly cause outbreaks from here on out. And while monkeypox can be managed with preventative vaccines and treatments, the last thing the world needs right now is trouble from another emerging infectious disease.
This article has been updated with comments from Andrew Pavia and Jo Walker.