Prevalence and Pathology Associated with Sarcocystis spp. in Raptors in Tennessee, USA

Raptors may serve as both intermediate and definitive hosts for Sarcocystis spp. Past research has documented fatal encephalitis in raptors caused by various Sarcocystis spp., whereas other surveys have found a high prevalence of tissue cysts without evidence of disease. Little is known about the prevalence of Sarcocystis in raptors in the eastern USA. The aim of this study was to determine the occurrence of tissue cysts and histopathologic changes associated with Sarcocystis spp. infection in raptors in eastern Tennessee. Tissues of 33 raptors from Tennessee, USA, were assessed with histopathologic examination. Cysts consistent with Sarcocystis spp. were present in the heart, skeletal, or tracheal muscle of 11 (33%) raptors, without any associated inflammation. Tissues from histopathologic-positive raptors were then tested with PCR targeting of the 18S rRNA gene of Sarcocystis. Sequence analysis of PCR products revealed that six raptors had sequences most similar to Sarcocystis falcatula, and two had sequences most similar to Sarcocystis halieti. In addition, one S. falcatula-positive Bald Eagle (Haliaeetus leucocephalus) had lymphoplasmacytic meningoencephalitis and was positive via immunohistochemistry for eastern equine encephalitis virus. Our study supports findings in other geographic regions that raptors commonly serve as hosts for Sarcocystis spp. without evidence of associated disease.