Prevalence of avian hematozoa in central Vermont.

Peripheral blood smears from 1,547 birds, of 50 species, from 15 families trapped in Northfield, Vermont were examined for hematozoa. Numerous new host-parasite relationships were identified. The prevalence of all species of parasites over the 3 yr of the study was 42.5%. Prevalence of the genera of parasites were: Leucocytozoon--36.5%; Trypanosoma--7.3%; Haemoproteus--6.3%; microfilariae--1.0%; Plasmodium--1.0%. Peak prevalence (78.9%) occurred in the first half of July. Peak intensity was seen in the last half of June. Evidence from immature birds suggested that active transmission of all genera of hematozoans took place in the study area. Leucocytozoon gametocytes, unlike Haemoproteus gametocytes, were detected in smears from birds during all seasons of the year, and showed no period of complete remission. Trypanosoma and microfilariae also were seen throughout the year.