Meeting Abstract
7.1 Tuesday, Jan. 4 Direct and indirect costs of co-infection in the wild: linking GI parasite communities, host hematology, and immune function BUDISCHAK, S.A.*; JOLLES, A.E.; EZENWA, V.O.; Univ. of Georgia; Oregon State Univ.; Univ. of Georgia sabudischak@gmail.com
Most animals are concurrently infected with multiple parasites and interactions among these parasites may influence disease dynamics, host immune function, and fitness. Consequences of co-infection may depend on the specific combination of parasite species present, but there is a paucity of data on both the direct and indirect (e.g. immune-mediated) costs of co-infection. We examined the effects of gastrointestinal (GI) parasite community richness and species identity on host immune function and condition using hematology data from wild African buffalo (Syncerus caffer). After controlling for individual host traits (i.e. age, sex, body condition), investment in immunity (lymphocytes) was associated with lower hemoglobin, hematocrit, and red blood cell size. Increasing GI parasite richness was also correlated with decreasing hemoglobin, hematocrit and red blood cell size. In a subset of hosts where we identified GI nematodes to species, hemoglobin levels and red blood cell counts decreased as the relative abundance of blood-sucking nematode species increased. By contrast, the abundance of a non-blood sucking nematode species was associated with decreased hematocrit and red blood cell size, but not hemoglobin or red blood cell count. Overall, co-infected individuals had lower hemoglobin levels than uninfected and singly-infected animals, but lymphocyte counts were indistinguishable among uninfected, singly-infected, and co-infected buffalo. Together these results suggest that increasing parasite taxonomic richness can negatively impact host condition, and specific effects may depend on species identity. Investment in immune defense also has costs detectable as changes in baseline hematology, but we did not find any difference in immune costs associated with parasite species identity or richness.
