The first recorded case of a person passing monkeypox to a dog could be a harbinger of other animals catching the virus, which can sometimes be disfiguring and deadly. If that happens, monkeypox could establish animal reservoirs outside of Africa for the first time.
Two men in France appear to have spread monkeypox to your italian greyhoundresearchers report August 10 in the Lancet. The men reported letting the dog sleep in the bed with them.
Monkeypox can be spread through skin-to-skin contact, such as intimate contact that occurs during sexual intercourse. Even more casual contacts like dancing in closed spaces can spread the virus, a study from August 15 in Emerging infectious diseases suggests. The same goes for contact with objects used by an infected person, including bedding and clothing. Infectious monkeypox virus stay more often in such soft and porous materials than on hard surfaces, researchers report Aug. 11 in Emerging infectious diseases. About 60 percent of soft goods and 5 percent of hard surfaces tested still carried viable viruses for at least 15 days, the team found.
In the dog’s case, the animal developed pustules about 12 days after its owners reported symptoms. Viral DNA from one of the men matched that of the dog, suggesting that the human had infected an animal with monkeypox.
Monkeypox usually goes the other way, from animals, especially rodents in some parts of Africa, to people in “spin-off” or zoonotic infections. “This is a classic case of reverse zoonosis,” or spillover, in which a viral disease jumps from humans to animals, says Grant McFadden, a smallpox virologist at Arizona State University in Tempe.
Such spill events are quite common with other viruses; people are known to have transmitted COVID-19 to dogs, cats and zoo animals, for example (Serial Number: 5/3/20; Serial number: 03/31/20). Some smallpox viruses, including cowpox, can infect a wide range of species, while others, such as smallpox and a rabbitpox virus called myxoma virus, can infect only one or a few species.
It is not known how far monkeypox can spread among animal species other than rodents. Researchers have documented that the virus can infect 51 species, including apes and monkeysand other animals, including anteaters, porcupines and opossums.
Right now, monkeypox is endemic in some parts of Africa. But some scientists worry that the global outbreak, which has infected more than 36,000 people so far, it creates more opportunities for the virus to jump from humans to animals. If that happens, the virus could establish itself in animal populations around the world, creating new reservoirs that could cause repeated infections in humans and animals.
Preliminary research suggests that monkeypox may be capable of infect two to four times as many species than previously thought, researchers at the University of Liverpool in England report August 15 in a preprint on bioRxiv.org. The team used trained machine learning to consider the genetic makeup of the virus, the number of animal species in a genus known to be infected by the smallpox virus, the dietary composition of potential hosts, where the animals live and other factors that could contribute to a species becoming a new host for monkeypox, says virologist Marcus Blagrove.
About 80 percent of new potential monkeypox hosts are rodents or primates, the researchers predict. But domestic animals such as dogs and cats were also predicted to be susceptible to infection. The researchers didn’t know about the dog case in France when they made the prediction, Blagrove says, so the report of the canine infection “was a very good validation that the method works.”
Red foxes and brown rats are two potential monkeypox hosts that the researchers say are of particular concern. foxes (vulpes vulpes) rummage through garbage, which could put them in contact with items contaminated with monkeypox. brown rats (Rattus norvegicus) are already known hosts of cowpox. They are common in the sewers of Europe and could be infected through faeces containing monkeypox. Although the study emphasized the risk in Europe, where more than half of human monkeypox cases have been reported in the current outbreak, the findings could be applied more broadly. Brown rats are found in all continents except Antarctica. Red foxes roam much of the northern hemisphereincluding North and Central America, Europe, North Africa, and parts of Asia.
The study also names three European rodents that could become reservoir species. The grass field mouse (Apodemo uralensis), yellow-necked field mouse (Apodemus flavicollis) and alpine marmot (groundhog groundhog) all have pockets of large populations that could be ideal for transmitting the virus.
“These are examples of wild animals that could be a reservoir. We can’t say for sure, but they could be susceptible,” says Blagrove. Those species, along with foxes and brown rats, should be regularly inspected for monkeypox to prevent new reservoirs from establishing, he says.
But the fact that an animal can be infected with monkeypox does not mean that it can transmit it. “There is a difference between accidental hosts and a reservoir,” says Giliane de Souza Trindade, a smallpox virologist at the Federal University of Minas Gerais in Brazil. Accidental hosts are often dead ends for the virus. A true reservoir species must be able to transmit the virus from one animal to another, and sometimes to the humans it encounters.
If dogs can get monkeypox easily, they can spread it to humans, other dogs or other animals through feces or saliva, Trindade says. Pets that live with people who get monkeypox should be isolated from sick people and other animals outside the home, she says.
Trindade and her colleagues are preparing to study the pets of people who have monkeypox to see if the virus spreads easily to cats and dogs, she says. But she is more concerned about live animal markets. “The animals are in cages close together and people are passing by all the time.” Such environments are ripe for cross-species transmission of viruses. The COVID-19 pandemic probably had its start at a live animal market in Wuhan, China, researchers reported July 26 in Sciences.
McFadden stresses that the dog case is still an isolated report. “We don’t know if this is something weird or if we just haven’t paid attention to it.” For now, he tells her, efforts must focus on containing the human-to-human outbreak. While people with monkeypox should be careful not to spread the virus to their pets, this case shouldn’t cause undue concern, she says. “We’re not at the panic button stage yet.”
Scientists are still learning how monkeypox spreads between people. Some people can has monkeypox, but does not develop symptomsresearchers report August 16 in the Annals of Internal Medicine. It’s not known whether asymptomatic people can spread the virus to others, but if they can, vaccinating close contacts of symptomatic people may not be enough to contain the outbreak, the researchers warn.