LISBON, May 23 (Xinhua) -- A further 14 cases of human infection with the monkeypox virus were confirmed in Portugal, bringing the total number of infections to 37, the Directorate-General for Health (DGS) reported on Monday.

According to a statement from the Portuguese health authorities, cases of the disease were confirmed by the National Institute of Health Doutor Ricardo Jorge (INSA) in the North, Lisbon and Tagus Valley, and Algarve regions.

"Among the available samples, the West African clade (a subgroup of the virus) was identified through sequencing, which is the least aggressive," the DGS said in the statement.

According to the Portuguese health authorities, the identified cases are kept under clinical follow-up and are stable and on an outpatient basis.

"Epidemiological investigations of suspected cases that are being detected are ongoing, intending to identify chains of transmission and potential new cases and their respective contacts," said the statement.

The World Health Organization (WHO) has confirmed cases of monkeypox in 12 countries: the United States, Canada, Australia, Britain, Spain, Portugal, Germany, Belgium, Italy, the Netherlands, France, and Sweden.

These cases exclude the 21 countries where the disease is considered endemic, all in West and Central Africa.