Israel, Switzerland, and Austria are the latest countries to confirm cases of monkeypox, according to the BBC.
The virus is most common in remote parts of central and west Africa.
More than 80 cases have been confirmed in the recent outbreak in Europe, the U.S., Canada, and Australia.
This outbreak has taken scientists by surprise, but the risk to the wider public is said to be low. Most people who catch the virus recover within a few weeks, according to the UK's National Health Service.
Although there is no specific vaccine for monkeypox, several countries have said they are stocking smallpox vaccines, which are about 85% effective in preventing infection because the two viruses are quite similar, the BBC said.