Are People Spreading Mpox to Their Pets?

There’s no strong evidence that people with mpox can infect their pets, but the CDC still urges caution until more definitive analyses are done, according to a small study.

Among 191 swab samples from 34 companion animals — mostly dogs and cats — only 22 (12%) tested positive for mpox virus DNA, but this was mainly due to contamination from human cases, Clint Morgan, MS, of the CDC’s National Center for Emerging and Zoonotic Infectious Diseases, and colleagues reported in Emerging Infectious Diseases.

None of the animals showed outward signs of illness, the authors noted.

“No strong evidence exists to suggest that common companion animals, such as dogs or cats, are susceptible to infection with clade IIb [mpox virus],” the researchers wrote. “Given the high likelihood for exposure among most of these animals, the paucity of evidence indicating infection might indicate resistance to infection.”

As of July, there have been no cases of mpox confirmed in common domestic animals, the researchers said. In two cases outside the U.S., mpox viral DNA was detected in dogs, but there were no signs of infection in the animals apart from skin lesions — no virus cultured from those samples, no orthopoxvirus antibodies detected on serology.

To get a better handle on whether reverse zoonotic transmission exists with this clade of mpox virus, Morgan and colleagues from the CDC’s Multi-National Mpox Response’s One Health Team worked with state and local jurisdictions to collect blood and swab samples from companion animals (24 dogs, nine cats, and one rabbit), as well as environmental samples from animal objects such as beds, toys, and food and water dishes.

They performed real-time PCR, orthopoxvirus serology, and viral culture on those samples.

Ultimately, four dogs and one cat tested positive for mpox virus DNA (12% of animal samples), as did 25% of environmental samples (14/56), the researchers found.

Further testing on those positive samples indicated that 82% from animals and 93% from the environment were probably contaminated with DNA from people with mpox, they reported. There was no live virus cultured from those samples, nor were any anti-orthopoxvirus antibodies detected.

Two of the animals reportedly developed new skin lesions after their owners started having symptoms, but these lesions were negative for mpox virus on PCR, strongly suggesting the lesions or scabs on these animals were not the result of mpox infection, the researchers said.

They noted that a third of households (7/21) reported no change in contact with their animals, and all but one reported direct contact with each animal after the pet owners developed symptoms. “In most households we visited, recommended quarantine and infection control procedures were not consistently followed,” they wrote.

Thus, despite a high likelihood that pets were exposed to the mpox virus, there were no signs that the animals were infected, Morgan and colleagues concluded.

Nonetheless, pet owners who have mpox should limit their interactions with their animals until they’re no longer contagious — which CDC considers to be until lesions have fully healed, with new skin underneath.

That’s especially true for small households, the researchers said, as households with smaller shared spaces had a higher prevalence of mpox virus DNA.

Morgan and colleagues called for more research to fully determine the potential susceptibility of companion animals to clade IIb mpox virus.

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