Sustained human outbreak of a new MPXV clade I lineage in eastern Democratic Republic of the Congo

Abstract

Outbreaks of monkeypox (mpox) have historically resulted from zoonotic spillover of clade I monkeypox virus (MPXV) in Central Africa and clade II MPXV in West Africa. In 2022, subclade IIb caused a global epidemic linked to transmission through sexual contact. Here we describe the epidemiological and genomic features of an mpox outbreak in a mining region in eastern Democratic Republic of the Congo, caused by clade I MPXV. Surveillance data collected between September 2023 and January 2024 identified 241 suspected cases. Genomic analysis demonstrates a distinct clade I lineage divergent from previously circulating strains in the Democratic Republic of the Congo. Of the 108 polymerase chain reaction-confirmed mpox cases, the median age of individuals was 22 years, 51.9% were female and 29% were sex workers, suggesting a potential role for sexual transmission. The predominance of APOBEC3-type mutations and the estimated emergence time around mid-September 2023 imply recent sustained human-to-human transmission.

Fig. 1. Mapping number of reported mpox cases and genomics analysis, Kamituga, DRC.

a, Map of the DRC with provinces colored by the number of reported cases. MPXV genomes available are indicated by colored circles (31 January 2024). These are placed at the centroid of the town, the health zone or the province depending on the precision of the recorded location. b, Maximum likelihood phylogeny of clade I genomes, including those from the present study (indicated as 2023/24 and Kamituga samples), with all previously sequenced genomes publicly available on GenBank. A version of this phylogeny where individual tips are labeled with accession numbers, locations and dates can be found in Supplementary Figs. 1 and 2. c, The Kamituga cluster with reconstructed mutations indicated on the branches. Mutations are colored by whether they are consistent with APOBEC3 deamination (dark blue) or not (green). sub/site, substitutions per site.

Fig. 2. Epidemiologic curve and mpox cases disaggregated by age and sex, Kamituga, DRC.

a, Epidemiologic curve of Kamituga mpox outbreak (October 2023 to March 2024), DRC. b, Counts of suspected mpox cases disaggregated by age and sex (male in blue, female in pink).