Giardiasis in wild and captive bird populations: High prevalence in herons and budgerigars

Abstract

The prevalence of giardiasis was investigated in wild and captive bird populations by determining the presence of cysts in faecal samples or cloacal swabs by immunofluorescence or by direct examination of intestinal smears from necropsied animals for the presence of motile trophozoites. A total of 370 samples from 74 species of birds representing 16 orders were examined. Five orders of birds contained Giardia infections and prevalence ranged from 1.7 to 55%. Ciconiformes (herons) and Psittaciformes (budgerigars) had the highest prevalence of giardiasis being 55% and 46%, respectively. Trophozoites recovered from green‐backed herons and egrets were all morphologically identical to G. ardeae isolated from the great blue heron, whereas those from budgerigars were the same phenotypically as has been reported for G. psittaci. Anseriformes and Passeriformes had rates of giardiasis of 2.6% or less, while Falconiformes, although indicated as positive for Giardia had too few samples available to make an accurate assessment of prevalence. Phenotypic and genotypic differences between avian and mammalian Giardia suggested that the former may not be infectious to man, but that seasonal migration of birds may lead to contamination of watersheds with Giardia cysts of avian origin.

Keywords:

• Aviangiardiasis
• prevalence
• Giardia ardeae, Giardia spp.
• Ciconiformes
• Psittaciformes

Notes

To whom correspondence should be addressed at: Department of Cell Biology and Neuroanatomy, 4–135 Jackson Hall, School of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.