Several avian Sarcocystis species have been reported to induce central nervous signs. These include Sarcocystis neurona which is capable of inducing a central nervous disease in a broad range of avian and mammalian species such as horses, cats, and dogs, and Sarcocystis rileyi, the causative agents of equine protozoal myeloencephalitis in horses and the nonpathogenic condition “rice breast” in waterfowl, respectively. Sarcocystis falcatula, closely related to S. neurona, can cause neurologic disease in wild birds.2
Sarcocystis calchasi is a protozoal parasite and the causative agent of pigeon protozoal encephalitis (PPE), a neurological disease of the domestic pigeon. The Accipiter hawks shed large amounts of infectious sporocysts and are considered definitive hosts of the parasite, while the domestic pigeons are the only intermediate hosts. Sarcocystis calchasi has also been isolated from several parrot species.
The disease has two stages. During the first stage, pigeons develop diarrhea and become apathetic. Neurological signs such as incoordination develop about eight weeks after infection when tissue cysts are mainly located in skeletal muscles. This may lead to an increased predation rate by the final host, the Northern goshawk. The second stage is characterized by severe central nervous system signs: twisted necks, backward arching of the head, neck, and spine, circling, head pressing, and inability to stand or fly.
- Modulation of the host Th1 immune response in pigeon protozoal encephalitis caused by Sarcocystis calchasi. Philipp OliasEmail author, Anne Meyer, Robert Klopfleisch, Michael Lierz, Bernd Kaspers and Achim D Gruber Veterinary Research201344:10
- Histopathologic and Molecular Characterization of Sarcocystis calchasi Encephalitis in White-winged Doves (Zenaida asiatica) and Eurasian Collared Doves (Streptopelia decaocto), East-central Texas, USA, 2010–13 Carolyn L. Hodo,1,5 Derick B. Whitley,2 Sarah A. Hamer,3 Wayne V. Corapi,1 Karen Snowden,1 J. Jill Heatley,4 and Aline Rodrigues Hoffmann1 J Wildl Dis. 2016 Apr 28; 52(2): 395–399.