Monkeypox was first discovered in 1958 in monkey colonies and the first human case was in 1970. Symptoms are similar to smallpox but milder, including fever, headache, muscle aches and exhaustion. Around 20 countries have reported about 300 confirmed or suspected cases of monkeypox where it wasn't previously active. WHO is advising targeted vaccination for close contacts and recommends isolation for those infected to stop further spread.