Sarcocystis calchasi is distinct to Sarcocystis columbae sp. nov. from the wood pigeon ( Columba palumbus) and Sarcocystis sp. from the sparrowhawk ( Accipiter nisus)

Abstract

Sarcocystis calchasi has been identified as causative agent of a newly discovered central nervous disease in domestic pigeons ( Columba livia f. domestica) observed for the first time in Germany in 2006. Initial studies have indicated that this parasite is highly pathogenic for domestic pigeons after ingestion of low doses of sporocysts shed by the Northern goshawk ( Accipiter gentilis). Here we tested whether phylogenetically related birds might regularly harbor Sarcocystis species. Five wood pigeons ( Columba palumbus) and five sparrowhawks ( Accipiter nisus) from Northern Germany were examined. All birds were PCR negative for S. calchasi by universal primers. Instead, both avian species harbored two as yet undescribed Sarcocystis species. Light and transmission electron microscopy identified cysts in the skeletal muscle of wood pigeons of 56–156 μm in width. The cysts had a smooth surface without protrusions. Sporocysts derived from the small intestine of the sparrowhawks measured 11.88 μm × 8.34 μm. Polymerase chain reaction amplification and sequencing of the first internal transcribed spacer region (ITS-1), the 18S rRNA and the 28S rRNA gene comprising the variabel D2 and D3 domains further characterized them as two novel Sarcocystis species. S. calchasi displays a pairwise distance value of the ITS-1 region ranging between 0.165 and 0.195 with the Sarcocystis spp. from the wood pigeon and the sparrowhawk, respectively. A phylogenetic analysis further supported the existence of two new species.