Avian trypanosomes as models of hemoflagellate evolution.

In the 15 years since the last review on avian trypanosomes(1), there has been a steady accrual of information on the distribution and dynamics of trypanosome infections in wild bird populations. Recent immunological and biochemical studies provide evidence that several trypanosome species can parasitize an ecological guild of host species but the relative roles of avian host phylogeny and vector ecology remain unanswered. In this article, Victor Apanius reviews the habitat preferences and behavior of trypanosomes within the avian host and attempts to draw similarities in the strategy employed by the parasite for persistence in different vertebrate classes. Next, the question of host specificity is raised and recent evidence on the subject is examined with an eye toward understanding the distribution of trypanosome species in host communities.