Distribution of the hematozoa of Neotropical birds.

The literature pertaining to the prevalence of avian hematozoa in the Neotropics, together with unpublished records from the files of the International Reference Centre for Avian Haematozoa, has been examined with respect to the distribution of parasite genera by host family and region. The blood parasites of 35555 birds of 955 species (80 families) occurring in the Neotropics formed the basis for the comparisons. Only 3743 (10.5%) individuals harbored one or more species of hematozoa. Haemoproteus was the most commonly observed form exhibiting a 7.4% prevalence, followed by Plasmodium (1.9%), microfilaria (1.2%), Trypanosoma (0.6%), and Leucocytozoon (0.2%). Hematozoan prevalence varied markedly from region to region and among families. In comparison with a similar review of Nearctic avian hematozoan distribution, the Neotropics demonstrated a much lower prevalence and a near absence of Leucocytozoon.