Fatal Hemoprotozoal Infections in Multiple Avian Species in a Zoological Collection
American Association of Zoo Veterinarians Conference 2006
Shannon T. Ferrell1, DVM, DABVP (Avian), DACZM; Karen Snowden2, DVM, PhD; Annajane Marlar1, DVM, DACVO; Michael Garner3, DVM, DACVP; Nancy P. Lung1, VMD, MS
1Animal Health Department, Fort Worth Zoo, Fort Worth, TX, USA; 2Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA; 3Northwest ZooPath, Monroe, WA, USA
Hemoprotozoal infections in birds are well described and can range from asymptomatic to acutely fatal. The three commonly reported pathogenic avian hemoprotozoa are Plasmodium spp., Haemoproteus spp., and Leucocytozoon spp. Over an approximate 3-year span, two lesser flamingos (Phoeniconaias minor), two green jays (Cyanocorax yncas glaucescens), and two Montezuma oropendolas (Psarocolius montezuma) died peracutely with no premonitory signs at a zoological collection in the southern USA. At necropsy, the birds were in excellent body condition. Except for one green jay, the coelomic cavities were filled with a dark serosanguineous fluid. Profound splenomegaly and hepatomegaly were present. The livers were tan to purple with numerous, randomly distributed, red to black foci, ranging in size from 1–4 mm. The predominant histopathologic finding, except in one green jay, was large protozoan cysts in the hepatic parenchyma. Frozen tissue samples harvested at necropsy from the six cases were sent to the parasitology division of the Department of Pathobiology at the Texas A&M College of Veterinary Medicine for polymerase chain reaction to amplify the cytochrome B gene of the hemoprotozoa. The amplified gene sequences were compared to reference gene sequences for avian Plasmodium, Haemoproteus, and Leucocytozoon cytochrome B in the GenBank® database. The protozoal parasite within the hepatic parenchyma from the Montezuma oropendolas and the lesser flamingos was identified as Haemoproteus spp. Both green jays had Plasmodium spp. isolated from the submitted tissue samples. There are no reports in the literature documenting identified fatal hemoprotozoal infections in oropendolas, green jays, or lesser flamingos.