Study flags co-infection threat in southeastern rattlesnakes
Bottom line
Rattlesnakes in the southeastern US appear to be facing a substantial infectious disease burden, according to a new University of Georgia-led study published in Frontiers in Veterinary Science. Researchers evaluated more than 500 free-ranging snakes from 29 species in South Carolina and Florida and found that 44% carried more than one pathogen. The strongest signal was in pygmy rattlesnakes, which were more likely to test positive for Ophidiomyces ophidiicola, the fungus behind ophidiomycosis, and for the invasive lung parasite Raillietiella orientalis. The authors said that combination, along with bacterial and viral co-infections in some animals, could increase illness and mortality risk in already vulnerable wild snake populations. (frontiersin.org)
Why it matters: For veterinary professionals, the findings are a reminder that wildlife disease surveillance is increasingly about co-infection, not single-agent diagnosis. The study links visible skin disease with broader pathogen pressure and adds to evidence that R. orientalis is expanding in the Southeast, likely after introduction via invasive Burmese pythons. For veterinarians involved in wildlife, zoo, exotic, or rehabilitation work, that raises practical questions around differential diagnosis, necropsy workups, biosecurity, and the risk that stressed or immunocompromised snakes may be hit by overlapping fungal, parasitic, and infectious threats at once. (frontiersin.org)
What to watch: Expect follow-up work on whether these co-infections translate into population-level declines, especially in pygmy rattlesnakes and other conservation-sensitive species. (frontiersin.org)
A new University of Georgia-led field survey is sharpening concern about infectious disease pressure in wild snakes, especially rattlesnakes in the southeastern US. Published May 2026 in Frontiers in Veterinary Science, the study assessed more than 500 free-ranging snakes across two wetland sites in South Carolina and Florida and found that nearly half carried multiple pathogens. Pygmy rattlesnakes stood out as a high-risk species, with elevated detection of both ophidiomycosis and the invasive lung parasite Raillietiella orientalis. (frontiersin.org)
The backdrop here is a long-building wildlife health story. Ophidiomycosis, also called snake fungal disease, has been recognized for years as a conservation threat in North American snakes and first drew major attention after fatal infections in rattlesnakes. Separately, R. orientalis has spread in Florida and beyond after being linked to invasive Burmese pythons, raising concern that a non-native parasite is adding a new layer of pressure to native snake populations. (usgs.gov)
In the new study, investigators screened for a range of pathogens, including Cryptosporidium, Hepatozoon, Mycoplasma, Salmonella, serpentoviruses, Ophidiomyces ophidiicola, and R. orientalis. Across the study population, 44% of snakes had more than one pathogen detected. According to the University of Georgia summary and Frontiers coverage, the fungus and the lung parasite appeared to be the most important infectious agents in free-ranging snakes in the southeastern US, with pygmy rattlesnakes showing particular vulnerability. (frontiersin.org)
That concern is consistent with earlier pathology work in free-ranging pygmy rattlesnakes from central Florida. A 2025 paper indexed in PubMed found all 17 snakes examined had fungal dermatitis consistent with ophidiomycosis plus mixed endoparasitism, while some also had ferlaviral pneumonia or gastric cryptosporidiosis. The authors concluded that mixed-pathogen co-infections were common and warranted closer study for their health and fitness effects in native Florida snakes. (pubmed.ncbi.nlm.nih.gov)
Public comments around the new study have been measured but pointed. In Frontiers’ news release, first author Dr. Corinna Mishin said O. ophidiicola and R. orientalis “appear to be the most important infectious agents” in free-ranging southeastern snakes. The work was funded by the Morris Animal Foundation, and the University of Georgia framed the findings as evidence that combined fungal, parasitic, and bacterial infections could push some snake species closer to extinction risk. (frontiersin.org)
Why it matters: For veterinary professionals, this is less about a single wildlife headline and more about a changing disease ecology. Co-infection can complicate clinical assessment, lesion interpretation, prognosis, and postmortem findings. It also reinforces the value of coordinated surveillance across wildlife agencies, diagnostic labs, academic centers, and exotic animal clinicians. For veterinarians who see confiscated, wild-caught, or rehabilitating reptiles, the spread of R. orientalis also has relevance beyond free-ranging populations, because the parasite has been flagged as a concern for pet trade movement and for snakes exposed to prey sourced from affected regions. (journals.sagepub.com)
There are also conservation and welfare implications. Species that are already under habitat or climate stress may have less margin when multiple pathogens circulate at once. The new paper does not by itself prove population decline, but it strengthens the case that disease burden should be included in management planning for sensitive snake species, particularly rattlesnakes and federally protected taxa with known ophidiomycosis susceptibility. (frontiersin.org)
What to watch: The next phase will likely focus on longitudinal monitoring, regional spread of R. orientalis, and whether repeated co-infection events translate into measurable survival or reproduction losses in wild snake populations. (frontiersin.org)