Monkeypox Outbreak in Monkeys Linked to Squirrel Consumption
- In a significant step toward understanding the origins of mpox (formerly known as monkeypox), researchers have traced a recent outbreak among a group of sooty mangabeys in Côte...
- The outbreak, which began in early 2023, affected roughly one-third of the mangabey troop in Taï National Park, tragically resulting in the deaths of four infants.
- “One big question for us has been, ‘where are the nonhuman primates getting infected from?’” explains Livia Patrono, a veterinarian and disease ecologist at the Helmholtz Institute for...
In a significant step toward understanding the origins of mpox (formerly known as monkeypox), researchers have traced a recent outbreak among a group of sooty mangabeys in Côte d’Ivoire to a surprising source: the fire-footed rope squirrel. The findings, published on in Nature, represent the first documented instance of mpox virus jumping directly from a rodent to a non-human primate in the wild.
The outbreak, which began in early , affected roughly one-third of the mangabey troop in Taï National Park, tragically resulting in the deaths of four infants. Prior to this discovery, mpox outbreaks in primates within the park – observed in and again in and among chimpanzees – remained a mystery, as the primates themselves were not found to be harboring the virus outside of outbreak periods.
“One big question for us has been, ‘where are the nonhuman primates getting infected from?’” explains Livia Patrono, a veterinarian and disease ecologist at the Helmholtz Institute for One Health in Greifswald, Germany. For years, Patrono and her colleagues have been systematically testing rodents within the park to pinpoint potential reservoir hosts – species in which the virus can persist without causing illness.
African rodents, particularly various squirrel species, have long been suspected of playing a crucial role in the emergence of mpox. The first virus isolated from wildlife came from a Thomas’s rope squirrel, and habitats of these squirrels frequently overlap with areas where human mpox cases originate. Even historical evidence, with mpox virus detected in museum specimens of rope squirrels dating back to , points to a long-standing presence of the virus within these rodent populations.
The breakthrough came through extensive wildlife monitoring, including analysis of fecal samples and necropsies of deceased animals. Researchers tested over 700 rodents, ultimately identifying a single positive case: a deceased fire-footed rope squirrel found approximately 3 kilometers from the mangabey troop, just 12 weeks before the outbreak began. Genetic analysis confirmed a close relationship between the virus found in the squirrel and the one that sickened the mangabeys, though not an exact match, suggesting the possibility of other infected squirrels contributing to the spread.
Crucially, the team uncovered direct evidence of consumption. Archival video footage from showed a mangabey eating a fire-footed rope squirrel. Further analysis of fecal samples collected from the mangabeys *before* the outbreak revealed rope squirrel DNA in two samples. One of these samples also tested positive for mpox virus, and was collected from the monkey believed to be the first infected individual. “That was a pretty, let’s say, informative piece of evidence saying that [a fire-footed rope squirrel] was a very likely source of infection for the mangabeys,” Patrono stated.
This discovery has significant implications for public health. Viral spillovers from animals to humans are believed to be the primary driver of human mpox outbreaks. Pinpointing the animal reservoirs allows for targeted prevention strategies. Clement Meseko, a veterinarian and virologist at the National Veterinary Research Institute in Vom, Nigeria, notes that officials could advise individuals living or working near fire-footed squirrels to utilize personal protective equipment when handling them, and to practice thorough handwashing.
While the fire-footed rope squirrel has been identified as a key source in this particular outbreak, researchers emphasize that other rodents likely carry the virus as well. This suggests that multiple species may pose an ongoing threat of zoonotic transmission – the spread of disease from animals to humans. Further research is needed to fully understand the complex dynamics of mpox transmission within the ecosystem and to develop comprehensive strategies to mitigate the risk of future outbreaks, both in animal populations and in humans.
The identification of the rope squirrel as a source underscores the importance of continued wildlife surveillance and the need for a One Health approach – recognizing the interconnectedness of human, animal, and environmental health – in preventing and controlling emerging infectious diseases.