New Delhi, Dec 13
Health officials in Spain have documented the first-ever case of human-to-human transmission of mpox clade 1b outside endemic regions in Africa.

Mpox is a viral infectious disease that spreads through close contact, causing fever, swollen lymph nodes, and skin rash. It spreads primarily through skin-to-skin contact.

Mpox clade 1b is a highly transmissible strain that emerged during an outbreak in the Democratic Republic of the Congo in 2023.

The case, documented in the International Journal of Infectious Diseases, stated that the 49-year-old patient had received two doses of the Imvanex smallpox/mpox vaccine and had no known travel history.

The man presented himself to a clinic in Madrid on October 10, with a single genital ulcer and swollen, painful lymph nodes in his groin area.

The patient also reported sexual contact with two local partners, neither of whom had travelled to endemic regions. After ruling out other sexually transmitted diseases, the health officials confirmed an infection with mpox clade 1b with a polymerase chain reaction (PCR) test of the lesion.

“To our knowledge, this is the first report of a case of Mpox clade Ib without epidemiological history of travel to Africa in the index patient or their previous sexual contacts, reported by Spanish Public Health authorities on 10 October 2025,” said Jorge-Alfredo Pérez-García, from Centro Sanitario Sandoval/Hospital Clínico San Carlos, in Spain, in the paper.

“Before this time, cases had already been reported across several countries, both in Europe and in the rest of the world, but were always associated with individuals who travelled to a country with known Mpox clade Ib transmission and were likely exposed there, or with individuals who did not travel personally but had direct contact with someone who did,” the researcher added.

In Spain, there is only one reported case of clade Ib in a patient who had travelled to Tanzania, with risk exposure occurring within the previous 21 days, specifically on September 22, and who has no epidemiological link to the case presented here.

Several countries in Africa have sustained human-to-human transmission of mpox clade 1b. The first case reported outside of Africa was in a Swedish national who travelled to an endemic African region.

Cases have been detected in countries outside of Africa since then, though almost all have been in people who recently travelled to endemic African countries or who had contact with others who had travelled to those regions.

The health officials urged taking the necessary measures to minimise both the clinical and public health consequences, especially in groups that are particularly vulnerable in previous Mpox outbreaks since 2022, such as people living with HIV, men who have sex with men, and persons with multiple sexual partners.

A total of 2,501 new confirmed cases, including 12 deaths due to mpox, were reported from 44 countries in October, said the World Health Organization (WHO), in its latest update.

Spain confirms 1st human transmission of mpox clade 1b outside Africa