How do mpox outbreaks start? Dead baby monkey provides important clue
April 8, 2025
A new preprint study has identified the fire-footed rope squirrel as a likely reservoir for mpox after an outbreak among mangabeys in Ivory Coast’s Taï National Park. Researchers traced the virus to a dead squirrel found months before the primate cases, suggesting cross-species transmission likely triggered the outbreak. The virus, previously believed to circulate primarily among rodents, may persist in rope squirrel populations. This breakthrough advances understanding of mpox’s zoonotic origins and raises questions about human-wildlife interactions in endemic areas. Scientists say this could help prevent future outbreaks by targeting surveillance and intervention where animal-to-human spillover risk is highest.
An mpox outbreak in a mangabey troop in Ivory Coast’s Taï National Park has led researchers to identify a likely wildlife reservoir: the fire-footed rope squirrel. The study, now available as a preprint on Research Square, offers the strongest evidence to date of a direct animal source for the virus, which has been increasingly impacting both wildlife and humans across Africa.
The initial clue emerged in January 2023, when scientists noticed skin lesions on a baby mangabey, soon followed by widespread illness in its troop. Subsequent testing confirmed monkeypox virus (MPXV), and genomic sequencing tied the strain back to a dead rope squirrel discovered two months earlier. Importantly, MPXV was also found in mangabey feces taken before symptoms appeared, suggesting the virus circulated asymptomatically for weeks. One fecal sample even contained squirrel DNA, indicating the likely route of transmission—predation or scavenging.
Although mpox has long been suspected to have rodent reservoirs, previous links were inconclusive. The discovery of genetically identical virus strains in both mangabeys and a rope squirrel, however, strongly implicates these rodents as key players in mpox ecology. While it’s not definitive proof that fire-footed rope squirrels are the exclusive reservoir, the evidence aligns with the species’ known range and the locations of frequent human mpox outbreaks.
Experts like Africa CDC’s Dr. Yap Boum and virologist Martine Peeters see this finding as a critical step in guiding proactive public health strategies. Understanding where and how zoonotic transmission occurs is crucial, especially as many mpox spillovers are linked to bushmeat consumption or close contact with wild animals.
As the WHO and African governments continue battling mpox with vaccines and surveillance, pinpointing its ecological source offers hope for prevention. Still, further study is needed, particularly to determine how often these squirrels are infected and whether they can spread the virus without falling ill themselves.