Mass. monkeypox case raises transmission questions

BOSTON — A Massachusetts man is just the 50th recorded case of monkeypox in the United States — but the first to contract the virus without a history of either travel to West Africa, where monkeypox is endemic , or known exposure to an infected animal.

That puts this case in the same mysterious category as several recent cases in Europe. In the United Kingdom, health authorities are investigating nine recent cases of monkeypox -- only one had a link to travel. Outbreaks have also occurred in Portugal and Spain — though it’s unclear if the cases there have a connection to West African travel.

One thing is known: most of the cases are in men and, in the case of the United Kingdom cases, four infections developed in men who self-disclosed they had sex with other men.

That is also, apparently true of the Massachusetts case, said Erica Shenoy, MD, PhD, associate chief of the Infection Control Unit at Massachusetts General Hospital.

“And that makes sense because the way this is spread is both through respiratory droplets,” she said. “And  through direct contact with the lesions that have virus in them.”

But this also makes no sense — at least in terms of the conventional wisdom about monkeypox. Because it is not considered a sexually transmitted disease. And if it now is, why would some cases — as it appears now — be confined to homosexual encounters?

That’s why these outbreaks, while small, merit watching closely, said Anne Rimoin, PhD, MPH, an epidemiology professor at UCLA who’s researched and written extensively about monkeypox.

“Are we seeing a change in transmissibility, are we seeing a change in virulence,” Rimoin said. “Is it becoming more severe over time, is it transmitting more easily over time? We have no indication of that at this point. What we’re seeing is that it’s now spreading in a variety of different places. So what we need is the data. We need to understand how it got into these people and have we seen increased human to human transmission.”

Rimoin said cases of disease caused by pox viruses have been increasing globally — and with good reason. About 40 years ago, smallpox was declared eradicated because of intensive vaccination efforts in previous years. Once that disease disappeared, so did a reason to get vaccinated for it.

“So it makes sense when we see other pox viruses circulating in the population that we now are vulnerable,” Rimoin said. “If you’re exposed to a pox virus you have not been vaccinated against smallpox.”

Or, if you have been vaccinated against smallpox, it was a long time ago — with routine smallpox vaccination ending in 1972 in the United States — and about eight years later, worldwide.

And that means immunity is likely waning, Rimoin said.

While the outbreaks in Europe and the case in Massachusetts are concerning, doctors say this is not a time to panic — especially with a pandemic still going strong.

“What I would be much more concerned about is preventing ongoing spread of COVID,” Rimoin said.

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