Transmission of MPXV from fire-footed rope squirrels to sooty mangabeys
Summary
Researchers investigating an mpox (MPXV) outbreak among a habituated group of sooty mangabeys (Cercocebus atys) in Taï National Park, Côte d’Ivoire, provide strong evidence that fire-footed rope squirrels (Funisciurus pyrropus) transmitted MPXV to mangabeys. The team combined long-term behavioural monitoring, extensive non-invasive faecal sampling, targeted trapping and necropsies of small mammals, viral genome sequencing and diet metabarcoding. They found a dead fire-footed rope squirrel positive for MPXV with viable virus isolated; near-identical viral genomes were recovered from the squirrel and infected mangabeys; and one mangabey faecal sample contained both MPXV DNA and squirrel DNA — suggesting a recent cross-species transmission event likely linked to predation or scavenging. The outbreak affected about 32.5% of the mangabey group, caused several deaths among infants and circulated undetected for weeks before clinical signs were observed.
Key Points
- MPXV was isolated from a dead fire-footed rope squirrel found ~12 weeks before the mangabey outbreak and ~3 km from the mangabey territory; organs and swabs carried high viral loads and live virus was cultured.
- Near-complete MPXV genomes from the squirrel and mangabeys were almost identical (excluding a few indel differences), placing them within local clade IIa diversity and suggesting a recent cross-species transmission.
- Faecal screening of the mangabey group (444 samples total) detected MPXV DNA in 36 samples from 19 individuals — including asymptomatic animals and mothers of symptomatic infants — indicating subclinical circulation.
- Metabarcoding of pre-outbreak faeces revealed fire-footed rope squirrel DNA in two samples; one of these was the earliest MPXV-positive faecal sample from the suspected index mangabey, showing co-detection of squirrel and MPXV DNA.
- Behavioural records and videos confirm mangabeys hunt and consume fire-footed rope squirrels, providing a plausible transmission route via predation or handling of infected prey.
- Squirrels occupy fragmented habitats and plantations near villages and are part of local bushmeat trade, highlighting potential spillover pathways to humans as well as to non-human primates.
Why should I read this
Short answer: because it’s one of the clearest real-world links we’ve had between a wild rodent and a primate mpox outbreak. The paper pulls together field observation, diet DNA, trapping/necropsy work and genome sequencing — and even catches a probable transmission in the act (squirrel DNA + MPXV in the same faecal sample). If you care about zoonoses, One Health, or how bushmeat and small mammal ecology shape spillover risk, this saves you time: they did the heavy lifting and the evidence hangs together.
Context and relevance
Why this matters: identifying reservoir hosts and transmission pathways is critical to reduce spillover risk and to target surveillance and public-health messaging. For decades squirrels have been suspected MPXV hosts; this study gives direct, multidisciplinary evidence that fire-footed rope squirrels can carry viable virus and can plausibly infect wild non-human primates through predation or scavenging. The finding strengthens the case that multiple small mammal species may maintain MPXV in nature and that human behaviours (bushmeat hunting, handling of small rodents, and habitat fragmentation) increase exposure risk.
Implications:
- Surveillance: increase targeted MPXV monitoring in rodents (especially Funisciurus spp.) and in people who hunt or handle small mammals near forest edges.
- Public health and conservation: co-designed awareness and risk-reduction measures are needed in communities that trap/sell squirrels — simple interventions could reduce both human and wildlife risk.
- Research priorities: study MPXV dynamics in rope-squirrel populations, their habitat use near villages, and the potential involvement of additional reservoir species.