Study finds widespread coinfections in southeastern wild snakes

A new multipathogen survey suggests wild snakes in the southeastern U.S. are facing a broader infectious disease burden than many clinicians and wildlife managers may have appreciated. In a study published in Frontiers in Veterinary Science and publicized on May 26, 2026, investigators sampled 509 free-ranging snakes representing 29 species and found that 44.0% carried coinfections. Among the most consequential findings: snake fungal disease caused by Ophidiomyces ophidiicola and the invasive lung parasite Raillietiella orientalis emerged as key threats, with pygmy rattlesnakes appearing particularly hard hit. (frontiersin.org)

The work builds on years of concern about ophidiomycosis, an emerging disease of conservation importance in North American snakes. USGS notes that snake fungal disease has been documented in numerous species and was initially recognized as a serious threat in rattlesnakes, where severe infections were thought to endanger population viability. At the same time, Florida researchers have been tracking the spread of R. orientalis, an invasive pentastome believed to have entered the U.S. with Burmese pythons and then spilled over into native snake populations. (usgs.gov)

In the new study, researchers conducted monthly sampling from May 2022 through May 2024 at wetland sites in Volusia County, Florida, and Jasper County, South Carolina, with additional opportunistic sampling in Georgia and diagnostic case inclusion from 2021 to 2024. They screened for seven pathogen groups. Beyond the headline pathogens, they detected Salmonella enterica in 62.6% of snakes, Hepatozoon spp. in 53.4%, Mycoplasma spp. in 17.5%, and Cryptosporidium spp. in 2.0%; no serpentoviruses were detected. Detection of O. ophidiicola or R. orientalis was negatively associated with nutritional condition scores, reinforcing the possibility that these infections are doing more than simply marking exposure. (frontiersin.org)

The rattlesnake signal is what makes the paper especially notable. According to the Frontiers news release and ScienceDaily coverage, pygmy rattlesnakes were frequently infected with both the fungus and the lung parasite. That fits with a separate 2026 pathology report in pygmy rattlesnakes from central Florida, which found all 17 examined snakes had fungal dermatitis consistent with ophidiomycosis plus mixed endoparasitism, including R. orientalis. The authors of that report said coinfections were common and warranted more study for their effects on host health and fitness. (sciencedaily.com)

Investigators also offered a plausible clinical explanation for why these combinations may matter. In comments distributed through EurekAlert, first author Dr. Corinna Mishin said increased ophidiomycosis risk was strongly associated with coinfections, and explained that once an animal becomes sick from one infection, immune compromise can raise the risk of further disease exacerbation from agents that may previously have been subclinical. That's not proof of direct causality, but it supports a syndemic-style view of disease pressure in free-ranging snakes. (eurekalert.org)

Why it matters: For veterinarians, this is a wildlife story with practical crossover into diagnostics, pathology, rehabilitation, zoo and aquarium medicine, and even biosecurity around captive reptiles. A single-lesion or single-pathogen workup may miss the larger picture in snakes from endemic regions, particularly in the Southeast. The expanding footprint of R. orientalis also matters beyond free-ranging wildlife: prior reports have documented the parasite in pet trade snakes, underscoring the porous boundary between wild and captive reptile health. For clinicians advising pet parents, rehabilitators, or collection managers, the study is another reminder that emerging reptile pathogens don't stay neatly confined to one setting. (journals.sagepub.com)

What to watch: The next questions are population-level. Researchers and conservation groups are already framing ophidiomycosis and R. orientalis as potential contributors to local declines or extinctions in vulnerable native snakes, and the new survey gives them broader surveillance data to build on. Watch for follow-up work on mortality, reproductive effects, host susceptibility by species, and whether coinfection patterns can help guide field surveillance and biosecurity policy in the Southeast. (oriannesociety.org)