Hepatic Hemorrhage, Hemocoelom, and Sudden Death due to Haemoproteus Infection in Passerine Birds: Eleven Cases

Abstract

Abstract. Haemoproteus spp. are ancient apicomplexan hemoparasites that have undergone extensive coevolution with their natural hosts and are typically species specific, with inapparent or minimal pathogenicity. A promiscuous genotype of Haemoproteus capable of undergoing host switching on a familial level was identified. This protozoan caused severe disease with high mortality in 6 species of exotic passerine birds housed in California at the San Diego Zoo's Wild Animal Park: Surinam crested oropendola (Psarocolius decumanus decumanus), Guianan turquoise tanager (Tangara mexicana mexicana), blue-necked tanager (Tangara cyanicollis caeruleocephala, Guianan red-capped cardinal (Paroaria gularis gularis), magnificent bird of paradise (Diphyllodes magnificus hunsteini), and superb bird of paradise (Lophorina superba). The birds had few or no clinical signs. Necropsy findings consisted of hemocoelom and irregularly scattered areas of hemorrhage and hepatocellular necrosis. Affected areas of liver contained solitary protozoal megaloschizonts in varied states of degeneration and peripheral nonsuppurative inflammation. No other parasite life stages were found in parenchymal organs or blood smears. Polymerase chain reaction using consensus primers for an avian malarial mitochondrial cytochrome B gene segment was positive in all cases. Sequencing and BLAST analysis identified the protozoan as a Haemoproteus sp. related to Haemoproteus spp. found in asymptomatic passerine birds native to North America. In situ hybridization was performed in 3 animals with a mitochondrial cytochrome B probe and was positive only in megaloschizonts. These findings suggest the recognition of a genotype of Haemoproteus that exhibits high levels of host infidelity and causes severe disease in captive birds exotic to North America.

Prevalence of Pseudo-malaria (Haemoproteus spp.) Infection in Many Species of Birds

“…It is the most common blood parasite of birds and has been reported from 67% of total bird species (7).The pathogenicity of this parasite can vary depending upon the species of the parasite from altered physiology up to mortality (8,18). Haemoproteus columbae widely occurs in pigeon in tropical and subtropical regions.…”

“…The highest percentage of infection with this parasite was in pigeon (63.3%), many of researches reported a high infection in feral pigeon, the present study agree with previous researches (17,20,21). Also some researches record infection in quail, domestic ducks, chickens and house sparrow (8,10,11,18,22).…”

“…(10) Infected birds may suffer from reluctance to move, ruffled appearance, prostration and death. Other findings include parasitemia and anemia (8,11). Large megaloschizonts may be present in skeletal muscles, particularly those of the thighs and back.…”

“…These organs may appear chocolatebrown due to hemozoin deposition. Cytologic imprints may reveal schizont-laden endothelial cells (6,8). Some species of Haemoproteus will also form large, cyst-like bodies within the skeletal muscles that resembling those seen with Sarcocystis species infections (9).…”

“…In other avian species, anemia and anorexia have been reported occasionally (8,14). Importantly, new records of Haemoproteus are discovered constantly and should still be monitored for effects on host condition (15).…”