The DGS added, in a statement, that the identified cases remain under clinical follow-up, and are stable.

The new cases were confirmed by the National Institute of Health Doctor Ricardo Jorge (INSA) late yesterday afternoon, with two samples still being analysed.

Regarding the remaining suspected cases, the DGS says that the samples will still be sent for analysis by INSA.

At the moment, the statement said, “epidemiological surveys are still ongoing, with the aim of identifying transmission chains and potential new cases and their respective contacts”.

The health authority appeals to people who have ulcerative lesions, skin rash, palpable lymph nodes, possibly accompanied by fever, chills, headache, muscle pain and tiredness, to seek clinical advice.

The director of the National Program for Sexually Transmitted Infections and HIV confirmed that the first five confirmed cases were detected at a clinic linked to sexually transmitted diseases in young men aged between 20 and 50 years old.

“They were identified in the context of care at a sexually transmitted disease clinic because they had genital lesions. The route of sexual transmission is not classically described [as likely to cause this infection], but there is transmission through close, intimate and prolonged contact”, said Margarida Tavares.

All cases, she stressed, are located in the region of Lisbon and Vale do Tejo.

“But for now we don't know if there is a relationship. And yes, there can be dispersion across the country,” she added.

The Monkeypox virus is of the Orthopoxvirus genus (smallpox is the best known of this genus) and the disease is transmitted through contact with animals, or close contact with infected people or contaminated materials.

The disease is rare and usually does not spread easily among humans.

This is the first time that Monkeypox virus infection has been detected in Portugal.

In 2003, a few dozen cases were reported in the United States of America.

The United Kingdom also recently reported similar cases of ulcerative lesions, with confirmation of Monkeypox virus infection.