Can Frogs Tell us how to Avoid Extinction?

The Centrolene prosoblepon, a frog native to Countries in Central America, is one of the many amphibians affected by the chytrid fungus disease. Source: Flickr

Think the black plague, but worse. It’s called the chytrid fungus disease, and you don’t have to worry about it unless you’re a frog or salamander. While the black plague killed about 30 to 50 percent of the worldwide human population, the chytrid fungus has been able to wipe off whole amphibian populations off the map. Researchers at the Smithsonian Tropical Research Institute (STRI) in Panama have published their study, Shifts in Disease Dynamics in a Tropical Amphibian Assemblage are not due to Pathogen Attenuation, in the March 30 edition of Science detailing the results of this epidemic and its implications for disease-related extinction.

The researchers were lucky as they saw the epidemic coming from Costa Rica to Panama, and were able to study the amphibians and the disease during and after its peak. Researchers were able to examine the various interactions hosts had with the pathogen because they collected host samples and pathogen from before, during, and after the epidemic occurred. They specifically tract infection patterns and virulence, species numbers and communities, and their resistance to the pathogen.

Recovery of nine amphibian species between five and 13 years was observed even though the fungus, Batrachochytrium dendrobatidis, was still present. After noticing that the skin secretion of wild frogs inhibited fungus growth remarkably more than the secretion from frogs moved into captivity before the disease arrived, researchers hypothesized that the wild frogs became more resistant to the disease. Think of the notion that kids should eat dirt to build up their immune system. If an organism is never exposed to various environmental elements, their body will never learn how to resist them, making it extremely difficult to combat disease.

Roberto Ibáñez, a STRI staff scientist and in-country director of the Panama Amphibian Rescue and Conservation Project said, It is vital to understand how disease transitions work — from outbreak, to epidemic, to coexistence — and our results have implications for a skyrocketing human population facing emerging diseases with the potential to cause global pandemics.” The results of this study and others relating to highly virulent disease systems suggest that some disease dynamics may be primarily driven by host factors – such as the ability of the organism to develop pathogen resistance or genetic variation – specifically when infectious agents remain highly pathogenic (disease causing). These findings have expanded our understanding of the spatiotemporal changes in host-pathogen interactions.

Jamie Voyles, Douglas C. Woodhams, Veronica Saenz, Allison Q. Byrne, Rachel Perez, Gabriela Rios-Sotelo, Mason J. Ryan, Molly C. Bletz, Florence Ann Sobell, Shawna McLetchie, Laura Reinert, Erica Bree Rosenblum, Louise A. Rollins-Smith, Roberto Ibáñez, Julie M. Ray, Edgardo J. Griffith, Heidi Ross, Corinne L. Richards-Zawacki. Shifts in disease dynamics in a tropical amphibian assemblage are not due to pathogen attenuationScience, 2018; DOI: 10.1126/science.aao4806v