Follow-up question: Is there actually a “new” monkeypox at all or is this the same virus African doctors have been managing for years, suddenly spreading in Europe for reasons that remain unclear?

Either way, the trends aren’t great.

Confirmed #monkeypox cases now in 11 countries, according to @globaldothealth case tracker. 39 additional cases confirmed so far today. pic.twitter.com/zGPTs9O1gJ

— Kristen Panthagani, MD, PhD (@kmpanthagani) May 20, 2022

Today’s global cases are double the number recorded on Wednesday. Cases have also doubled in the UK. The virus has been found on at least four continents in the past month, suggesting that something has changed about it qualitatively. But if it has, it’s curious that Africa isn’t seeing an unusually large outbreak this year. Worldwide through the first (almost) five months of 2022, 1,300 cases and 58 deaths have been recorded. Through the first eight months of 2020, more than 4,500 cases and 171 deaths were tracked by the WHO.

If monkeypox has mutated into some more infectious version of monkeypox, we’d expect the evidence to have emerged in Africa first. It hasn’t.

How then to explain the strangely high number of infections in Europe? Some scientists have a theory, which this quote from a WHO official points to: “As we enter the summer season in the European region, with mass gatherings, festivals and parties, I am concerned that transmission could accelerate, as the cases currently being detected are among those engaging in sexual activity, and the symptoms are unfamiliar to many.” Is the new monkeypox — *if* there’s a new monkeypox — more prone to being transmitted sexually?

Dr. Jeremy Faust has been studying the outbreak in Europe and discovered that all 89 confirmed cases have something in common.

Against the idea that this virus is more easily transmitted than earlier variants—say through smaller droplets or via the air—is that among the 89 cases being investigated for whom we know the gender, all 89 are males, a large number of whom are young and middle-aged adults. Public health agencies have reported that this monkeypox outbreak has been spreading in males who have had sexual contact with other infected males (or members of a shared sexual network). However, we do not know if that is true in some, many, most, or all of the cases.

Still, what we do know suggests strongly, to me at least, that monkeypox may still be primarily spreading through sexual contact, a known major mode of transmission. It could be that this virus has not gained any newfound stability in the air or in droplets—and that would certainly be welcome news—but that it is spreading with greater ease than usual (and therefore via more casual contact) in sexual networks, due to some genetic changes in the virus.

If the virus were spreading through the air via respiratory droplets, we’d expect some women to have been infected by now. As it is, health authorities in Britain, Spain, and Portugal have said that a “notable proportion” of infected patients are gay or bisexual men.

Does that mean the “new” monkeypox is specific to gays? There’s no reason to think so. The virus has always been known to spread through the air during sustained close contact, which is inescapable in sex of any sort. It may appear specific to gays at the moment simply because it’s spreading through sexual contact between men who don’t have sex with women. More from virologist Angela Rasmussen (“MSM” means “men who have sex with men” here):

If there’s spread within a sexual network followed by travel, that could easily explain why clusters are popping up in other countries within those extended networks.

Monkeypox has a fairly long incubation period. Lots of time for people to travel before the first vesicles pop.

— Dr. Angela Rasmussen (@angie_rasmussen) May 20, 2022

The good news is that we’d expect many more cases if the virus had made a quantum leap in airborne transmission and we’re not seeing that. But even so, we’re left with the mystery of “Why now?” If this is the same old monkeypox that scientists have known about for years, we’d expect these occasional outbreaks within sexual networks in the U.S. and Europe every year. As it is, this one is unusual. Something must have changed genetically about the virus itself, as Faust suggests, no?

“I’m stunned by this. Every day I wake up and there are more countries infected,” said Oyewale Tomori, a virologist who formerly headed the Nigerian Academy of Science and who sits on several World Health Organization advisory boards.

“This is not the kind of spread we’ve seen in West Africa, so there may be something new happening in the West,” he said.

The irony is that we’re victims of our own success here to some extent. “The smallpox vaccine incidentally protected against monkeypox,” Ed Yong notes. “And when new generations were born into a world without either smallpox or smallpox-vaccination campaigns, they grew up vulnerable to monkeypox.” I’d be curious to know the age demographics of the 89 infected patients so far. Older men will have been vaccinated for smallpox as children whereas younger ones wouldn’t. Would a shot received 60 years ago still provide some protection against monkeypox today?

Even if not, Yong offers two bits of good news. First, due to government fears of a bioterror attack from Russia, there’s enough smallpox vaccine stockpiled to immunize virtually the entire U.S. population if need be. If monkeypox takes off, the feds should be able to move quickly to protect people. Second, there’s already a therapeutic that also (probably) works called TPOXX. That’s been stockpiled too.

Bottom line: If you’re going to lie awake worrying about a disease, COVID’s still the one to worry about, not monkeypox. But just in case that’s too cheery a sentiment coming from me, here’s Scott Gottlieb to scare you a little bit.

"Now there has been community spread it may be hard to fully snuff this out. I don't think it is going to become a major epidemic because this is a virus that is difficult to spread," says @ScottGottliebMD on monkeypox. "I don't think it's going to be widespread." pic.twitter.com/bq1mgxRSMQ

— Squawk Box (@SquawkCNBC) May 20, 2022