Aug 25, 2022 - Science

How monkeypox spreads

Confirmed monkeypox cases per 100k residents
Data: CDC, U.S. Census; Chart: Erin Davis/Axios Visuals

Public health messaging around how monkeypox is and can be transmitted needs to greatly improve so that individuals can assess their own risks, several experts tell Axios.

Why it matters: There are multiple transmission routes for a virus that's now in every state and has become a public health emergency. These include close body contact, air and surfaces — but the primary route currently appears to be personal, often skin-to-skin contact.

What's happening: While the majority of cases are concentrated among men who have sex with other men, there are also some cases in the general population, including children.

  • This has led to concern that the virus is spreading via airborne particles, like COVID-19, or on surfaces, like smallpox.
  • "There is some evidence that monkeypox can be transmitted by droplet transmission," says Julie Fischer, microbiologist and senior technical adviser for CRDF Global. "Is it airborne in the sense that people can be infected far away? I think we still don't have enough data to say, and, obviously, people are still very scarred by conversation happening around COVID-19."
  • But, the main risk factor appears to be prolonged close contact with an infected person, Fischer adds.

While research is ongoing, most experts that Axios spoke with feel the primary method is via close bodily contact with an infected person's lesions, which are thought to have high concentrations of viral DNA.

  • People can transmit it by other means to household members, but that's not seen as a primary mechanism, says Angela Rasmussen, a virologist at the University of Saskatchewan's Vaccine and Infectious Disease Organization.
  • As for close bodily contact, it's unknown "whether that's due to sexual transmission by semen or other body fluids, or whether that's just close skin-to-skin contact. It could be a combination of both," Rasmussen says.

Surface transmission, via shared bedding, clothing, or other objects, is also possible, but it doesn't appear to be a main transmission route, Rasmussen says.

  • "It's a known transmission route, via fomites [objects] or indirect contact transmission, but it doesn't seem to be a major factor in this epidemic. That's not to say that it's not happening, but the epidemiology really doesn't suggest that is the case because if it were, we would see a lot more household transmission than we're seeing now," Rasmussen says.

The CDC says it is researching if the virus can be spread via an asymptomatic person.

  • It's also looking at the role of respiratory secretions as well as if they can transmit via semen, vaginal fluids, urine or feces.

What's next: "This is a containable outbreak that's been made much worse by human factors," says Amesh Adalja, senior scholar for Johns Hopkins University's Center for Health Security.

  • "We know where that risk group is, and we know if we can get the vaccine into that group, if we're aggressively testing in that group, this is something I think can be contained. I think eventually because of immunity from infection, immunity from vaccination, plus people's behavior change, this will smolder and hopefully burn out," Adalja says.

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