The World Health Organization (WHO) called for vigorous contact tracing of a spate cases of the rare disease monkeypox in a growing number of countries.
Italy and Sweden on Thursday became the latest countries to report cases of the rare disease, but cases have also been reported recently in Spain, Portugal, the United States and Britain.
The general public and health clinics should be aware and have unusual skin rashes examined by specialist staff, the WHO said on Wednesday. If monkeypox is suspected, patients should be isolated, the health body continued.
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."
First case in Italy
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 was in isolation in a hospital in Rome.
In Spain, eight infections were reported in the capital Madrid and another 23 suspected cases are under study, according to health authorities. In Portugal, the newspaper Público reported that some 20 people had been infected.
The majority of the cases reported so far involve men who have had sexual contact with other men.
The United States Centers for Disease Control and Prevention (CDC) announced on Wednesday that a US person had been infected.
A case in Massachusetts
A resident of the US state of Massachusetts in the country's north-east was tested Tuesday night, with the CDC labs confirming monkeypox the following afternoon. The infected person had recently travelled to Canada using private transport, the CDC noted.
The case follows multiple clusters of monkeypox recently reported in countries where the disease is not usually found, including Britain.
The number of cases detected there rose to nine, the UK Health and Safety Authority said Wednesday. The first, detected in early May, was a person who had recently travelled to Nigeria.
Canadian broadcaster CBC reported that health officials in Quebec are investigating cases of monkeypox after being notified a visitor to the province was later confirmed as a case.
Endemic disease in RDC
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.
British authorities have advised the public, in particular men who have sex with men, to be alert to any lesions on their bodies, as several recent monkeypox cases were detected in gay men.
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 where the virus is known to be present. 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.