Transmission of MPXV from fire-footed rope squirrels to sooty mangabeys

Abstract Mpox, caused by the monkeypox virus (MPXV; Orthopoxvirus monkeypox ), is on the rise in West and Central Africa 1–3 . African rodents, especially squirrels, are suspected to be involved in MPXV emergence, but no evidence of a direct transmission to humans or non-human primates has been established 4–9 . Here we describe an outbreak of MPXV in a group of wild sooty mangabeys ( Cercocebus atys ) in Taï National Park (Côte d’Ivoire). The outbreak affected one-third of the group, killing four infants. To track its origin, we analysed rodents and wildlife carcasses from the region. We identified a MPXV-infected fire-footed rope squirrel ( Funisciurus pyrropus ), found dead 3 km from the mangabey territory 12 weeks before the outbreak. MPXV genomes from the squirrel and the mangabey were nearly identical. A video record from 2014 showed a mangabey from this group eating the same squirrel species and diet metabarcoding of faecal samples collected from mangabeys before the outbreak identified two samples containing fire-footed rope squirrel DNA. One of these samples was also the first positive for MPXV. This represents a rare case of direct detection of interspecies transmission. Our findings indicate that rope squirrels were the source of the MPXV outbreak in mangabeys. Because squirrels and non-human primates are hunted, traded and consumed by humans in West and Central Africa 10,11 , exposure to these animals probably represents risk for zoonotic transmission of MPXV.