Meeting Abstract
Disease is one of the leading factors contributing to the global decline of amphibians. While diseases such as chytrid fungus and ranavirus have been implicated in amphibian decline, considerably less is known about how blood protozoa, such as trypanosomes, affect amphibian populations. Furthermore, despite the common occurrence of trypanosome infection in amphibian populations, we still know relatively little about how amphibians respond to trypanosome infection. In this study, we characterize differential white blood cell counts—the relative proportion of five different immune cell types in the blood—in four anuran species (Rana catesbeiana, Rana sphenocephala, Rana blairi, Hyla cinerea) with and without trypanosomes. Frogs were wild caught and naturally infected with one to four distinct trypanosome morphotypes, differing in size, presence of a free flagellum, and cell motility. Trypanosome species can have multiple morphological stages in their life cycles, however the species associations of amphibian trypanosome morphotypes are not known. In this study, we found differences in white blood cell differentials between infected and uninfected individuals of a given species. For example, trypanosome infection was associated with lowered lymphocyte counts in R. catesbeiana, while trypanosome infection was associated with lowered neutrophil counts in R. sphenocephala. Additionally, white blood cell profiles differed depending on the specific trypanosome morphotypes present. This study helps characterize one of the immunological responses of anuran amphibians to trypanosome infection and provides insight into how blood protozoa interact with their amphibian hosts at an immunological level.
