Twelve percent of swabs taken from the fur, mouth, and anorectal area of pets living with an mpox patient tested positive for mpox virus DNA, but blood cultures showed no signs of infection, according to a new US study.
Centers for Disease Control and Prevention researchers worked with public health officials in Minnesota, Tennessee, Virginia, and Washington, DC, to collect swabs from 34 pets from 21 households that included at least one infectious mpox patient from July 2022 to March 2023.
The pets were swabbed within 21 days of direct contact with the patient and again 3 or 4 months later, if possible. The researchers sampled the fur, abdomen, mouth, anorectal region, and any lesions of 24 dogs, 9 cats, and 1 rabbit.
The team also collected swabs from animal beds, toys, and dishes. They also tested and cultured the animals' blood samples and evaluated sera for any orthopoxvirus antibodies (mpox is an orthopoxvirus). Mpox patients were surveyed about the pet, household, and contact with the pet or other animals.
The results were published yesterday in Emerging Infectious Diseases.
Mpox primarily zoonotic before 2022
Before the outbreak that began in spring 2022, mpox transmission was primarily zoonotic (from animals to people), with limited human-to-human spread. But after 2022, an mpox variant—clade 2—spread via direct contact among humans, primarily through sexual networks outside of endemic regions, the authors noted.
"As of July 2024, no cases of mpox infection or mpox disease had been confirmed in common domestic animals, such as dogs and cats, during the current global outbreak or any past outbreaks," they wrote.
High likelihood of human contamination
A total of 22 of 191 (12%) of animal swabs and 14 of 56 (25%) of environmental samples from four households tested positive for mpox DNA, but blood samples from the four dogs and one cat showed no viable mpox or orthopoxvirus antibodies that would indicate previous infection.
Given high likelihood for exposure among most of these animals, the paucity of evidence indicating infection might indicate resistance to infection.
Of the mpox-positive swabs, 82% from the pets and 93% from the environment suggested DNA contamination from infected humans.
"Given high likelihood for exposure among most of these animals, the paucity of evidence indicating infection might indicate resistance to infection," the researchers concluded.
They urged mpox patients to avoid contact with animals until their lesions have fully healed and encouraged public health officials to take a One Health approach to investigate potential spillback of human infections to animals.
