Italy and Sweden have became the latest countries to report cases of the rare disease monkeypox, with the United Kingdom, Spain, Portugal and the United States already dealing with the outbreak.

Monkeypox occurs in central and west Africa, often in proximity to tropical rainforests, and is considered endemic in the Democratic Republic of Congo, where it was first discovered in humans in 1970.

The illness can be transmitted from person to person through air droplets, close bodily contact or sharing contaminated linens or objects.

According to the Swedish Public Health Agency, one person is infected in the greater Stockholm area. 

“The person infected with the virus in Sweden is not seriously ill but is receiving treatment,” infectious disease expert Klara Sonden said in a statement.

“We do not yet know where the person became infected. The investigation into this is ongoing.”

A first monkeypox infection has also been detected in Italy.

The health chief of the Lazio region, Alessio D’Amato, said on Facebook that the case had been confirmed at Italy’s National Institute for Infectious Diseases.

The ANSA news agency reported that the infected man had returned from a trip to Spain’s Canary Islands and is in isolation in a hospital in Rome.

The French Health Ministry said on Thursday the first suspected case of the monkeypox virus on French territory has been detected in the Paris/Ile-de-France region.

The World Health Organisation, already busy with the coronavirus pandemic which has struck the world over the past three years, has called for vigorous contact tracing of the spate of cases.

So far, four countries in Africa have reported cases of monkeypox in 2022, namely Cameroon, Central African Republic, Democratic Republic of Congo and Nigeria, the WHO said.

The general public and health clinics should be aware and have unusual skin rashes examined by specialist staff, the WHO said in a separate statement. 

If monkeypox is suspected, patients should be isolated, the health body continued.

The US Centers for Disease Control and Prevention announced on Wednesday that a person there had been infected.

A resident of the US state of Massachusetts in the country’s northeast was tested on Tuesday, with the CDC labs confirming monkeypox the following day.

The infected person had recently travelled to Canada using private transport, the CDC noted.

Canadian broadcaster CBC reported that health officials in Quebec are investigating if monkeypox has broken out there after being notified a visitor to the province was later confirmed as a case.

In Spain, eight infections were reported in the capital Madrid, according to Europa Press news agency, citing health authorities. 

In Portugal, the newspaper Público reported that 20 people had been infected.

The majority of the cases reported so far involve men who have had sexual contact with other men.

The number of cases detected in the UK has risen to nine, health authorities said on Wednesday.

The first, detected in early May, was a person who had recently travelled to Nigeria.

UK authorities have advised the public, in particular men who have sex with men, to be alert to any lesions on their bodies.

The virus usually causes symptoms similar to smallpox but milder. 

Cases can also be severe. 

Smallpox has been considered eradicated worldwide since 1980 after a major vaccination campaign.

Experts suspect that the pathogen that causes monkeypox circulates in rodents – monkeys are so-called false hosts.

According to the WHO, previous cases of monkeypox were usually due to travel to areas in west and central Africa. 

The WHO said monkeypox has appeared more frequently in Nigeria in recent years. 

Since 2017, a total of 558 suspected cases have been reported there. 

Of those, 241 have been confirmed and eight people have died.

with reporting from Reuters