HELSINKI -- Swedish health authorities confirmed on Thursday that they have identified the first case of the more infectious Clade I variant of mpox in the country.

The Public Health Agency of Sweden said this is also the first confirmed case of this variant outside Africa.

Magnus Gisslen, the state epidemiologist at the health agency, said in a press release that the patient contracted the infection during a visit to the region in Africa where mpox Clade I is spreading.

The news came a day after the World Health Organization (WHO) declared mpox a public health emergency of international concern.

The Swedish health agency noted that, unlike the previous variant which mainly spread through sexual contact, Clade I is now spreading primarily through household contacts and frequently infects children. Though it causes a similar illness to the Clade IIb variant that spread internationally in 2022, Clade I is considered capable of causing a more severe condition and higher mortality.

The agency said that Sweden is prepared for the diagnosis, treatment, and isolation of Clade I patients. It had previously indicated that isolated cases of the variant might be expected in the country.

Sweden reported around 300 mpox Clade IIb cases in the previous wave of infection.