First case of mpox with monkeypox virus clade Ib outside Africa in a returning traveller, Sweden, August 2024: public health measures.

An unprecedented upsurge in mpox, caused by clade I of the monkeypox virus (MPXV) was noted in Central Africa in 2024. The first mpox case with MPXV clade Ib outside Africa was reported in Sweden in mid-August. The case experienced a mild disease course after travelling to an affected country. No additional cases of this clade have been detected in Sweden. Strengthened public health measures and surveillance including whole genome sequencing are crucial to prevent establishment of novel MPXV clades.