There is a risk that monkeypox could become endemic in Europe if the current outbreak isn’t brought under control and the virus spills back into susceptible animal species, the European Centre for Disease Prevention and Control said Monday as it issued a risk assessment of the unprecedented event.
The health agency said that if person-to-person transmission continues and if the monkeypox virus were to make its way into animal species in the region, it could become entrenched, though it suggested the risk is thought to be “very low.”
“Currently, little is known about the suitability of European peri-domestic (mammalian) animal species to serve as a host for monkeypox virus,” the risk assessment stated, noting that rodents and squirrels are likely to be suitable hosts for the virus and transmission from people to pets is theoretically possible. “Such a spill-over event could potentially lead to the virus establishing in European wildlife and the disease becoming an endemic zoonosis.”
The agency noted that after a 2003 outbreak in the United States, public health authorities in this country did extensive surveillance looking for instances where the virus might have made its way into animals. But they found no evidence it had happened. The 2003 outbreak was traced back to infected small mammals imported from Ghana as pets — two rope squirrels, a Gambian rat, and three dormice. The animals infected nearby prairie dogs at a wholesale pet store and the prairie dogs infected 47 people in six states.
As of yet, the virus is considered endemic only in a dozen countries in West and Central Africa, where human infections occur sporadically. Prior to this year, there have been only a few exported cases of monkeypox detected outside of the endemic countries — in the United States, the United Kingdom, Israel, and Singapore.
The natural reservoir — the animal or animals that are the source of the virus — is not known.
“If human-to-animal transmission occurs, and the virus spreads in an animal population, there is a risk that the disease could become endemic in Europe,” the ECDC said in a statement. “As such, there needs to be a close intersectoral collaboration between human and veterinary public health authorities to manage exposed pets and prevent the disease from being transmitted to wildlife.”
The number of cases in the current outbreak is changing rapidly as countries search for cases. Maria Van Kerkhove, who leads the emerging diseases and zoonoses unit in the World Health Organization’s Health Emergencies Program, said Monday that to date there are fewer than 200 confirmed and suspected cases. Eleven countries in Europe, as well as the United States, Canada, Israel, and Australia have reported confirmed cases.
The virus currently appears to be spreading among men who have sex with men, though Van Kerkhove warned that surveillance is currently focused on finding cases through sexual health clinics. Casting a broader net will likely bring other cases to light, she and others have said.
Monkeypox is a pox virus and is related to the variola virus, which caused smallpox. That once dreaded disease was declared eradicated in 1980. The symptoms of monkeypox are similar to but milder than smallpox.
Infected people develop flu-like symptoms — fever, body aches, chills — but also swollen lymph nodes. With one to three days of the onset of fever, a distinctive rash appears, often starting on the face. Many conditions can cause rashes, but the monkeypox rash has some unusual features, notably the fact that vesicles can form on the palms of the hands. In this outbreak, a number of people have reported having had lesions on their genitals.
In countries where it is endemic, the virus is believed to mainly spread to people from infected animals when people kill or prepare bushmeat for consumption.
Once the virus jumps to people, human-to-human transmission can occur via respiratory droplets — virus-laced saliva that can infect the mucosal membranes of the eyes, nose, and throat — or by contact with monkeypox lesions or bodily fluids, with the virus entering through small cuts in the skin. It can also be transmitted by contact with clothing or linens contaminated with material from monkeypox lesions.
The ECDC said additional cases are likely.
“Most of the current cases have presented with mild disease symptoms, and for the broader population, the likelihood of spread is very low,” said ECDC Director Andrea Ammon. “However, the likelihood of further spread of the virus through close contact, for example during sexual activities among persons with multiple sexual partners, is considered to be high.”
The health agency recommended that the European Union and European Economic Area focus on prompt identification, management, and reporting of new monkeypox cases. Countries should also update their contact tracing mechanisms and their capacity to diagnose orthopoxviruses — the family to which monkeypox belongs — and review the availability of smallpox vaccines, antivirals, and personal protective equipment for health professionals.