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What methods do wildlife researchers employ to diagnose illness in endangered species? While the discovery of infectious microbes in animal feces can offer valuable insights, finding a microbe doesn’t necessarily correlate to observable symptoms. A recent study conducted by researchers from the University of Illinois Urbana-Champaign utilized sophisticated molecular techniques to assess the health of endangered Indiana bats, highlighting changes in their microbiomes due to parasitic infections.
According to Andrew Bennett, the lead author of the study and a postdoctoral researcher in the Department of Natural Resources and Environmental Sciences, conservation medicine faces unique challenges. “In conservation medicine, sick patients will rarely schedule a follow-up visit. This makes real-time tracking of disease impact complicated. We adopt a comprehensive perspective on microbial interactions within populations to deduce disease burden over time from individual snapshots,” Bennett explained.
To investigate these health indicators, Bennett and his team captured Indiana bats near a Missouri hibernation site, carefully collecting a single fecal sample from each bat. These samples were then analyzed in the lab, where researchers extracted DNA and identified gut microbes and parasites through a technique known as multiplex metabarcoding. They were also able to document alterations in the gut microbiome linked to the levels of parasitic presence.
The researchers identified the presence of Eimeria, a protozoan parasite residing in the gut that causes coccidiosis, which is known to lead to economic challenges in livestock. Bennett noted that while low levels of Eimeria may not be harmful, previous studies suggest that stress can trigger its proliferation, subsequently damaging gut tissues and opening the door to secondary bacterial infections.
“Our findings are significant because previously, the mere detection of Eimeria wouldn’t clarify if it was causing health issues,” Bennett added. “By examining microbiome changes associated with Eimeria loads in these bats, we develop a non-invasive marker that helps evaluate their gut health.”
Moreover, the study uncovered that bats with elevated Eimeria levels exhibited an increase in Clostridium bacteria, particularly strains associated with severe tissue damage in other animal species.
Joy O’Keefe, a co-author of the study and associate professor in NRES, indicated that the precise symptoms experienced by the infected bats remain speculative, as does the potential impact of Eimeria infections on their survival and overall population dynamics. “While we cannot pinpoint the stressors that may provoke harmful effects from Eimeria, this study establishes a foundational baseline for further investigations,” she commented. “It also allows us to relate findings to management strategies, roosting populations, and observed bat behaviors.”
Cory Suski, another co-author and professor in NRES, emphasized the added value that molecular tools bring to ecological research. “Traditionally, conservation efforts have focused primarily on counting individuals. A higher population often leads to the assumption of good health,” he stated. “This approach encourages deeper inquiry and access to information that exceeds mere numbers without the need for invasive capture methods.”
O’Keefe expressed hope that researchers will apply similar methodologies for other endangered bat species in North America, enabling a comparative analysis of their health status. This study underscores the importance of innovative research methods in addressing the challenges of wildlife conservation.
This research received support from the USDA National Institute of Food and Agriculture, Hatch project (ILLU-875-982), and from the Missouri Department of Conservation under Cooperative Agreement No. 418.
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