An outbreak of Sarcocystis calchasi encephalitis in multiple psittacine species within an enclosed zoological aviary

Abstract

A total of 5 psittacine birds in an enclosed zoological exhibit, including 2 princess parrots and 3 cockatoos of 2 different species, developed severe central nervous system clinical signs over a 2–3-month period and died or were euthanized. Histologically, all birds had a lymphoplasmacytic and histiocytic encephalitis with intralesional protozoa consistent with a Sarcocystis species in addition to intramuscular tissue sarcocysts. By immunohistochemical staining, merozoites in brain and tissue cysts in muscle did not react with polyclonal antisera against Sarcocystis falcatula, Sarcocystis neurona, Toxoplasma gondii, and Neospora caninum, or with a monoclonal antibody to S. neurona. Transmission electron microscopy on sarcocyst tissue cyst walls from 2 birds was morphologically consistent with Sarcocystis calchasi. Polymerase chain reaction (PCR) amplification and sequencing of partial 18S ribosomal RNA from muscle tissue cysts and brain schizonts from 3 birds was consistent with a clade containing S. calchasi and Sarcocystis columbae but could not distinguish these closely related Sarcocystis species. However, PCR amplification and sequencing of the internal transcribed spacer 1 RNA segment in the brain from 2 birds and muscle from 2 birds specifically identified the isolates as S. calchasi. The current report documents that multiple psittacine species are susceptible intermediate hosts of S. calchasi, and that infection can cause encephalitis resulting in significant morbidity and mortality in psittacine aviaries.

Parasite distribution and early-stage encephalitis inSarcocystis calchasiinfections in domestic pigeons (Columba liviaf.domestica)

“…Recently, several psittacine species have been reported as susceptible intermediate host species in natural and experimental infections. Clinical signs and pathologic lesions in these psittacines closely resembled PPE (Rimoldi et al, 2013;Olias et al, 2014). Since psittacines are phylogenetically only distantly related to pigeons, S. calchasi might be capable of using a broad spectrum of intermediate hosts, despite previous exclusion of chickens as potential intermediate hosts (Olias et al, 2010a).…”

Isolation, molecular characterization, and in vitro schizogonic development of Sarcocystis sp. ex Accipiter cooperii from a naturally infected Cooper's hawk (Accipiter cooperii)

“…However, little is known about the species diversity of these parasites and the types of intermediate hosts used in their life cycles [3]. They have the potential to be the source of fatal neurological disease in other avian species [4][5][6][7][8][9], and raptors themselves can also suffer from fatal neurological disease caused by Sarcocystis species [10][11][12][13].…”

“…We are interested in understanding the diversity of Sarcocystis species that use [7][8][9] but the definitive host has not yet been identified. Our hypothesis was that Copper's hawks would serve as definitive host for 1 of these 4 Sarcocystis species in North America.…”

Prevalence of Sarcocysts in the Muscles of Raptors from a Rehabilitation Center in North Carolina

“…Sarcocystis spp. oocysts/sporocysts excreted in the feces of raptors, such as Sarcocystis calchasi in Accipiter species hawks in Europe (Olias et al, 2010, have the potential to be a source of fatal disease in avian species in the wild (Wu¨nschmann et al, 2011;Olias et al, 2014;Hodo et al, 2016;Ziegler et al, 2018) and those housed in zoological exhibits (Rimoldi et al, 2013;Trupkiewicz et al, 2016).…”