Monkeypox does not tend to spread easily between people and the illness is usually mild, writes 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 US, 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.
The WHO said that the recent outbreaks were unusual in that they were occurring in countries where the disease was not endemic. It is not yet clear why this unexpected outbreak is happening now.
One possibility is that the virus has changed in some way, although currently there is little evidence to suggest this is a new variant. Another explanation is that the virus has found itself in the right place at the right time to thrive.
Monkeypox may also spread more easily than it did in the past, when the smallpox vaccine was widely used.
The UK Health Security Agency said that initial symptoms of monkeypox include fever, headache, muscle aches, backache, swollen lymph nodes, chills and exhaustion, writes lbc.co.uk.
A rash can develop, often beginning on the face, which then spreads to other parts of the body including the genitals. The rash can look like chickenpox or syphilis, and scabs can form which then fall off.
The incubation period of monkeypox is usually from six to 13 days but can range from five to 21 days.