In 2003, 47 people across six Midwestern states contracted monkeypox from pet prairie dogs infected after being housed with rodents imported from Ghana, Africa. Today’s outbreak, which has already infected more than 14,100 people in the U.S. and more than 41,000 worldwide, is spreading mainly through close human contact among gay and bisexual men. Recently, scientists reported the first presumed human-to-pet transmission in a dog in France, prompting U.S. and global health officials to issue warnings to prevent the virus from spreading to other pets and animals.

Concerns Over Animal Transmission

The recommendation to prevent monkeypox from spreading to animals stems from concerns that the virus could spill into wildlife or rodent populations as the human outbreak grows. This could create a situation where the virus passes back-and-forth between humans and animals, giving it a permanent foothold in countries where it hasn’t historically circulated. Before this year’s global outbreak, monkeypox primarily spread in remote parts of West and Central Africa through exposure to infected animals. The 2003 outbreak in the U.S. was the first documented case of humans catching the virus outside Africa.

The current global outbreak differs significantly from past patterns of transmission, with monkeypox spreading almost entirely through close physical contact between people in major urban areas in the U.S., Europe, and Brazil. However, the first presumed case of people infecting an animal in the current outbreak was reported in France when a pet dog tested positive for the virus after a couple in Paris fell ill with monkeypox and shared their bed with the animal.

Response from Health Officials

WHO officials have stated that a single incident of a pet catching the virus is not surprising or a cause for major concern. Still, there is a risk that monkeypox could start circulating in animals if people are unaware that they can infect other species. If monkeypox becomes established in animal populations outside Africa, the virus would have more opportunities to mutate, increasing the risk of higher transmissibility and severity. Animals could then potentially transmit the virus to humans, heightening the risk of future outbreaks.

Dr. Mike Ryan, director of the WHO’s health emergencies program, emphasized the importance of preventing the virus from moving between species. “It’s through that process of one animal affecting the next and the next and the next that you see rapid evolution of the virus,” he said.

Measures and Recommendations

The CDC has not received any reports of pets infected with monkeypox in the U.S., according to spokesperson Kristen Nordlund. However, the virus can spread from people to animals and vice versa. Nordlund noted that while the species of animals that can contract monkeypox is still being studied, it is assumed that any mammal can be infected. It is unlikely that reptiles, amphibians, or birds can contract monkeypox since they have not been found to be infected with viruses in the same family.

Dr. Rosamund Lewis, the WHO’s lead monkeypox expert, emphasized the importance of disposing of potentially contaminated waste properly to avoid the risk of rodents and other animals becoming infected when rummaging through garbage. “We believe that they are important enough that people should have information on how to protect their pets, as well as how to manage their waste, so that animals in general are not exposed to the monkeypox virus,” Lewis said.

Historical Context and Current Investigation

In the 2003 outbreak, the CDC quickly administered vaccines and quarantined patients before the virus could spread further. The CDC then banned the importation of rodents from Africa. Containing the 2003 outbreak required 10,000 hours of work to trace the virus back to Gambian rats and other rodents imported from Ghana to an animal distributor in Texas.

Public Health and Surveillance

Public health officials are concerned about the types of animals in urban settings in the U.S., such as raccoons, mice, and rats, and whether they can pick up and transmit the virus. Some types of mice and rats can get monkeypox, but not all species are susceptible, according to the CDC.

The CDC recommends that people who have monkeypox avoid contact with animals, including pets, livestock, and wildlife. If a pet becomes sick within 21 days of contact with someone who has monkeypox, the animal should be evaluated by a veterinarian. Waste contaminated with monkeypox should be disposed of in a lined, dedicated trash can and should not be left outside to prevent wildlife exposure.

Wastewater and Wildlife Concerns

Scientists in California detected monkeypox DNA in sewage samples this summer, raising concerns about the virus potentially infecting rodents through wastewater. New York is also conducting wastewater surveillance for the virus. Although it is unclear if live virus is present in wastewater, the findings have raised concern among health experts about the possibility of the virus gaining a foothold in animal populations.

“There is the risk because of the widespread nature of infections and the fact that it’s sewage and wastewater,” said Dr. James Lawler, an infectious disease expert at the University of Nebraska Medical Center. “That’s a concern about getting into an animal population and having a zoonotic risk reservoir.”

Better Surveillance Needed

Although the risk of the virus becoming entrenched in a U.S. animal population is low, the U.S. needs a more robust surveillance system to prepare for such a possibility, according to former CDC officials Marguerite Pappaioanou and Amira Roess. There are significant gaps in the ability of public health agencies to monitor animal populations for infectious diseases.

“It’s a very big gap. We don’t have a good surveillance system for humans,” Roess said. “For wildlife, it depends on who is interested in what pathogen and if they’re able to convince someone to fund surveillance. A lot of our surveillance is just really sporadic.”

Livestock such as cows, sheep, and poultry are monitored by the Department of Agriculture, but wildlife surveillance is underfunded and requires a tremendous amount of work. There is no government agency overseeing the health of dogs and cats, and local health departments may monitor rodents and have population control programs, but this also requires significant funding and staffing.

Conclusion

As urbanization increases, the risk of infectious diseases spreading between humans and animals becomes a more pressing concern. The work done by health officials and scientists is crucial in preventing another outbreak and ensuring public safety. Improved surveillance and proactive measures are essential to managing and mitigating the risks posed by diseases like monkeypox.