It started with people complaining of rashes that look like chickenpox at sexual health clinics in Europe after rave parties.
Authorities in some European countries, including the UK, Portugal and Spain, said the cases were mostly of men having sex with other men.
But the UNAIDS has apparently warned against any homophobic attempt to link the sickness to gay sex.
Their infections were discovered at the sexual health clinics when the infected went for help with skin rashes.
The main symptom of monkeypox is a rash that looks like chickenpox before turning into blisters and scabbing.
Earlier in the UK, health officials have suggested that sex at two raves in Europe could be to blame for the mysterious monkeypox outbreaks on the continent.
Although monkeypox is not a sexually transmitted infection (STI), it can be transmitted through direct contact during sex.
According to UK health experts, sex at festivals and raves may help spread monkeypox, adding that a significant proportion of cases in Britain and Europe have been in young men who are gay, bisexual, or have sex with men.
The infected haven’t been to Africa, where the disease is endemic and is typically spread by handling infected monkeys.
Monkeypox is typically a mild virus that causes fever, headache, and a distinctive bumpy skin rash, but it can be severe. Symptoms usually go away after two to four weeks.
Eleven African countries are considered endemic for the disease.
The WHO on Monday said it is possible to contain the monkeypox outbreaks in non-endemic countries. It said human-to-human transmission of the virus can also be stopped.
“We want to stop human-to-human transmission. We can do this in the non-endemic countries … This is a containable situation,” the WHO’s emerging diseases lead Maria Van Kerkhove said on social media.