A British study found no human-to-pet transmissions, even after reports of two such cases in Brazil and France primed fears that the virus could spill into a new wild-animal reservoir.
The risk of people with monkeypox passing the virus to their pets is low, the authors of a new study that found no such transmissions in the United Kingdom have concluded.
The study’s findings offer a broader perspective in the wake of two recently reported cases of apparent monkeypox transmission from humans to their pets, including a dog in France and a puppy in Brazil.
Such rare cases tap into fears that the global monkeypox outbreak could spill over from humans and become endemic in new populations of wild animals. Infectious disease experts anticipate that if such animal reservoirs of the virus were established, they could be impossible to eradicate, or at least challenging to control, and could spark new outbreaks among humans.
“I believe that such a risk is becoming higher,” said Huaiping Zhu, director of the Centre for Diseases Modeling at York University in Toronto, arguing that even with global cases declining, cases and the increasing number of rodents still translates to more risk. Zhu is the lead author of a separate study published in September in the Journal of Medical Virology that used mathematical modeling to project how monkeypox might spread from an animal host in a theoretical metropolitan area.
Since monkeypox was first discovered in a research monkey in 1958 and humans in 1970, the virus has become endemic in 11 western and central African nations. It has periodically jumped from animals to humans in the region, but until this year had not been documented spreading very widely from person to person. Thanks to what public health experts decry as a woeful lack of investment in monkeypox research predating this year’s outbreak, scientists remain uncertain which animals comprise the viral reservoir in Africa. It’s known that monkeypox can infect more than 50 mammal species and experts believe it may be endemic in wild rodent populations such as rope and sun squirrels, giant-pouched rats and African dormice.
Epidemiologists have expressed concern that animal-to-human transfers of viruses will only become more common as climate change and human encroachment upon wild areas increasingly bring people into contact with wild animals.
HIV, for example, is believed to have passed from nonhuman primates to humans in western Africa in the early 20th century. SARS-CoV-2, which causes Covid-19, is thought to have originated in bats in eastern China — although a highly politicized debate still rages over whether the coronavirus might have come from a lab.
Since June, the United Kingdom Health Security Agency and the Animal and Plant Health Agency have collected survey data regarding the pets of British people diagnosed with monkeypox. Through mid-September, 40 people with monkeypox reported owning 154 pets, including 42 dogs and 26 cats. The study’s authors documented in a paper published in the journal Eurosurveillance last week that none of these animals apparently developed symptoms suggesting monkeypox infection.
Acknowledging that their findings are likely based on “substantial under-reporting of pets associated with confirmed cases” of monkeypox, the researchers concluded that the risk of transmission of the virus from humans to their pets is low. However, they highlighted the possibility of monkeypox spilling over to rodents, which, they wrote, could then infect domesticated animals that could in turn transmit the virus to humans.
It remains possible, the study authors acknowledged, that there have been monkeypox infections in British pets that have gone under the radar, especially if the disease presents differently or asymptomatically in animals. Pet owners may also have refrained from disclosing suspected cases for fear of having their animals put into quarantine.
David Evans, a professor of medical microbiology and immunology at the University of Alberta, who was not involved with the British study, argued that the global monkeypox outbreak still remains small enough to allow for only a very small chance of the virus jumping from humans into a new wild-animal reservoir.