According to a UN expert, increasing pressure on ecosystems could lead to monkeypox infections in humans.
Threatened habitats and climate change would change the movement radius of animals and encourage the virus to spread to humans, said Mike Ryan of the World Health Organization (WHO) in Geneva on Thursday.
"We don't know if it's too late to contain it entirely," WHO smallpox expert Rosamund Lewis said of the virus.
However, she was optimistic that the spread can be combated with conventional hygiene measures.
According to the UN organization, more than 550 cases of monkeypox have been detected in 30 countries that have hardly been affected in the past few weeks.
The numbers do not include current infections in several African countries where the viral disease has recurred in the past.
"We're dealing with a pretty unstable interface between animals and humans," Ryan said in a news conference.
Increases can also be observed in other diseases of animal origin - such as Lassa fever or Ebola.
Various rodents and primates are known to be carriers of the monkeypox virus.
However, the new infections, which are mainly reported from Western countries, appear to have been transmitted from person to person.