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Penn State researcher says current monkeypox outbreak is unexpected but risks remain low

This electron microscopic (EM) image depicted a monkeypox virion. On the left were mature, oval-shaped virus particles, and on the right were the crescents, and spherical particles of immature virions.
Cynthia S. Goldsmith, Russell Regnery
Centers for Disease Control
This electron microscopic image depictes a monkeypox virion obtained from a clinical sample associated with the 2003 prairie dog outbreak.

More than 1,000 cases of monkeypox have been confirmed as of Monday in 29 countries, including the U.S., since May. Philadelphia reported a case last Thursday, which the Centers for Disease Control confirmed was the first in Pennsylvania.

WPSU’s Min Xian talked with Penn State researcher Sagan Friant, who has studied monkeypox outbreaks in Nigeria, about what’s known about these cases so far.

Here's the conversation:

Min Xian: Sagan Friant, thank you for joining us.

Sagan Friant: Yeah, thanks for having me.

Min Xian: The United Kingdom first reported a case of monkeypox on May 7th and has now accumulated more than 200 cases. (As of June 6, it has more than 300 cases.) Spain and Portugal have identified more than 100 cases each as well. The CDC says there are 24 cases in the U.S. as of Sunday (Thirty cases as of Monday). What do we know about this outbreak so far?

Sagan Friant: Monkeypox is one of these zoonotic diseases that outbreaks tend to be characterized by zoonotic transmission, or transmission from an animal host to a human, with limited human to human transmission.

But with this outbreak, what we're seeing now, is sustained human to human transmission. This is outside of endemic countries. So many of the export cases that we've seen in the past have had one or few or zero subsequent cases due to human to human contact. But now as we're seeing this multiple cases, multiple parts of the globe, you're seeing sustained human to human transmission that is very unexpected and something that we're keeping an eye on.

Min Xian: How is monkeypox transmitted?

Sagan Friant: Monkeypox is transmitted from close contact or large respiratory droplets. So it's not COVID. And I'll say that probably multiple times in this interview.

So it's transmitted from sustained close contact. And so it's not something that you'll get from somebody by casually walking by them down the street, you really need to be in contact with them, and receive virus from those pustules. The characteristic pustules that we see. And so you've probably heard that there's concern that it's sexually transmitted, but it's just that sexual activity requires close contact. So any type of close contact with somebody – or indirect contact with them through contaminated items. So often in areas where monkeypox is endemic, a lot of times you'll see transmission by contact with contaminated bedding from somebody who is taking care of somebody who had monkeypox.

Min Xian: One thing scientists, like yourself, do not know yet is in which animal population monkeypox regularly circulates on. And that's a critical and unknown factor. Can you talk about how this unknown factor affects our response to the virus in general?

Sagan Friant headshot
Courtesy of Sagan Friant
Sagan Friant is an assistant professor of anthropology and principal investigator of the RISK lab at Penn State. She studies the anthropology of human health risks, including the currently unknown origins of recent monkeypox outbreaks in Nigeria since 2017.

Sagan Friant: Yes, so monkeypox is a bit of a misnomer, as people are becoming aware of now. It was first discovered in a monkey, but the suspected hosts are small rodents, and there's evidence of the virus in a diversity of small rodents within central and west Africa. That contact with small rodents is how we think that people get the virus in these settings.

And so what we're seeing now is a different case of human to human transmission. So we're not able to track back these cases to a zoonotic origin.

There's lots of questions. One question is how are people interacting with animals in these endemic settings that lead to the transmission of monkeypox. We need to know what behaviors are leading to the transmission and, in some cases, it might be hunting wildlife. Occupationally exposed hunters, adults are the typical age group that we're seeing. But also children are often playing with small rodents or hunting them themselves. And so this can also lead to cases in children, which is pretty common in central and west Africa.

One thing that is concerning about monkeypox is the fact that we do know that it can infect a wide range of rodent reservoirs. And in 2003, we saw it infect prairie dogs in Wisconsin from importation cases of African rodents for the pet trade. And so we have seen it come into new animal hosts in the U.S. And humans got that infection from contact with those prairie dogs. And so one thing that we're keeping an eye out for is a possibility of what we call spillback, so the virus can spill over from animals to humans, and it can spill back into animals from humans. And we've seen some cases of this with COVID going into deer populations. There is concern that in domestic settings, whether it's with pet rats or with prairie domestic or rodents that are in the house, that we might see monkeypox spill back into rodent populations, and then it becomes a lot harder to eradicate.

Min Xian: Public health officials have said the current outbreak poses extremely low risk to the general public. So what should the public know about how monkeypox may or may not impact them?

Sagan Friant: Again, this is a different situation than with COVID. We're very prepared. We have a long history of research and control – worried about smallpox, monkeypox is closely related to smallpox. And a lot of the treatments and vaccines that developed for smallpox have some cross protection to monkeypox.

One of the theories of why we're seeing monkey pox emerge now, at more frequent rates, is that the smallpox vaccine stopped being implemented after a certain age. So my parents were vaccinated for smallpox. I wasn't vaccinated for smallpox. As the population of unvaccinated individuals grows, we're seeing increased spread, and as that population ages we're seeing increased susceptibility.

On the other hand, we have those treatments. We have some antivirals that have been approved for smallpox and more recently used for monkeypox effectively, as well as a vaccine on hand, which, because of the biodefense concerns with smallpox, we have large, from what I understand, large stockpiles of that vaccine. So we're pretty prepared to respond.

It's also not transmitted easily. And there's a longer period of between when somebody gets infected and shows symptoms. So we're able to do contact tracing a little bit more effectively than with COVID. And also, I should say that monkeypox is a very visible disease. So far, we know that you have to have symptoms to transmit the infection. And so we're able to track the infections a little bit easier than with COVID.

Min Xian: That's Sagan Friant, assistant professor of anthropology at Penn State. Thank you so much for talking with us.

Sagan Friant: Thanks for having me.

Min Xian reported at WPSU from 2016-2022.