TThere is a risk that monkeypox will become endemic in Europe if the current outbreak is not brought under control and the virus jumps back into susceptible animal species, the European Center for Disease Prevention and Control said on Monday when it published a risk assessment of the virus unprecedented risk issued event.
The health agency said that if human-to-human transmission continues and the monkeypox virus could find its way into animal species in the region, it could take hold, although it indicated the risk is assessed as “very low”.
“Currently, little is known about the suitability of European peridomestic (mammal) animal species to serve as hosts for the monkeypox virus,” the risk assessment said, noting that rodents and squirrels are likely suitable hosts for the virus and transmission from humans on pets is theoretically possible. “Such a spill-over event could potentially result in the virus becoming established in European wildlife and the disease becoming an endemic zoonosis.”
The agency noted that following a 2003 outbreak in the United States, public health officials in that country conducted extensive surveillance to look for cases where the virus might have entered animals. But they found no evidence it had happened. The 2003 outbreak was traced to infected small mammals brought in as pets from Ghana — two rope squirrels, a Gambian rat and three dormouse. The animals infected nearby prairie dogs at a wholesale pet store, and the prairie dogs infected 47 people in six states.
So far, the virus is considered endemic in only a dozen countries in West and Central Africa, where human infections occur sporadically. Before this year, few exported cases of monkeypox were detected outside of the endemic countries – the United States, Britain, Israel and Singapore.
The natural reservoir – the animal or animals that are the source of the virus – is unknown.
“If human-to-animal transmission occurs and the virus spreads in an animal population, there is a risk that the disease will become endemic in Europe,” the ECDC said in a statement. “Therefore, close intersectoral collaboration between human and veterinary health authorities is required to manage exposed pets and prevent the disease from being transmitted to wild animals.”
The number of cases in the current outbreak is changing rapidly as countries scramble for cases. Maria Van Kerkhove, who heads the division for emerging diseases and zoonoses in the World Health Organization’s health emergencies programme, said on Monday there were fewer than 200 confirmed and suspected cases to date. Eleven countries in Europe, as well as the United States, Canada, Israel and Australia have reported confirmed cases.
The virus appears to be spreading among men who have sex with men, although Van Kerkhove warned surveillance is currently focused on finding cases in sexual health clinics. Casting a wider net is likely to bring other cases to light, she and others have said.
Monkeypox is a smallpox virus related to the variola virus that caused smallpox. This once feared disease was declared eradicated in 1980. The symptoms of monkeypox are similar but milder than smallpox.
Infected people develop flu-like symptoms – fever, body aches, chills – but also swollen lymph nodes. One to three days after the onset of the fever, a prominent rash appears, often starting on the face. Many conditions can cause rashes, but monkeypox rash has some unusual features, most notably the fact that blisters can form on the palms of the hands. In this outbreak, several people have reported having lesions on their genitals.
In countries where it is endemic, the virus is believed to spread primarily from infected animals to humans when humans kill or prepare bushmeat for consumption.
Once the virus jumps to humans, human-to-human transmission can occur through respiratory droplets — virus-laced saliva that can infect the linings of the eyes, nose, and throat — or through contact with monkeypox lesions or body fluids containing the virus, which penetrate through small skin incisions penetration. It can also be transmitted through contact with clothing or bedding contaminated with material from monkeypox lesions.
ECDC said more cases were likely.
“Most of the current cases show mild symptoms of the disease and the likelihood of spread to the wider population is very low,” said ECDC Director Andrea Ammon. “However, the probability of further spread of the virus through close contact, for example during sexual activities between people with multiple sexual partners, is estimated to be high.”
The health agency recommended that the European Union and the European Economic Area focus on promptly identifying, treating and reporting new cases of monkeypox. Countries should also update their contact tracing mechanisms and capacity to diagnose orthopoxviruses — the family that includes monkeypox — and review the availability of smallpox vaccines, antivirals and personal protective equipment for healthcare professionals.