Sweden confirms first case of mpox strain circulating in Africa

Sweden said Thursday that it had confirmed a case of the more contagious version of mpox currently circulating in central and eastern Africa.

It is the first known infection of the strain outside of Africa.

On Wednesday, the World Health Organization declared mpox — formerly known as monkeypox — a global public health emergency for the second time in two years, following an outbreak in the Democratic Republic of Congo that has spread to 12 other countries in the region.

“We have now also during the afternoon had confirmation that we have one case in Sweden of the more grave type of mpox, the one called clade I,” Health and Social Affairs Minister Jakob Forssmed said in a news conference.

Mpox is a viral infection that spreads through close contact. It’s classified into two distinct viral groups, called clades: clade I and clade II. 

The strain that spread widely in 2022 and prompted the WHO’s first public health emergency declaration was a version of clade II. The current outbreak, however, is a version of clade I, which is “likely to be associated with a higher risk of a more severe course of disease and higher mortality,” according to the Public Health Agency of Sweden.

The agency said in a release that the patient with mpox sought care in Stockholm after spending time in Africa.

The version of clade I responsible for the outbreak in Congo also appears to be fairly transmissible via routine close contact, such as between members of a household. That’s a notable difference from the clade II strain, which was transmitted primarily via sexual contact among men who have sex with men during the outbreak two years ago.