Professor Desser's research program involves the study of the systematics, life history, morphology, epizootiology, ultrastructure and pathogenesis of protistan, moneran and certain viral parasites in their vertebrate and invertebrate hosts. Recent studies have focused on the blood parasites of fish, anurans and reptiles. Cumulative knowledge generated from this research coupled with biochemical and molecular biological data are being incorporated into studies of the life history and systematic relationships of these parasites and their historical associations with their hosts and vectors.