Sarcocystis calchasi Outbreak in Feral Rock Pigeons (Columba livia) in California

Abstract

Twenty-two feral rock pigeons ( Columba livia) from 10 counties in California with ataxia, torticollis, and difficulty standing and flying were admitted to rehabilitation centers in late winter and spring of 2017 and died or were euthanized. Common necropsy findings included thin body condition, generalized deep red discoloration of organs, and hemorrhagic subcutaneous neck tissues. Meningoencephalitis was observed microscopically in 16 pigeons, and 3 also had protozoal schizonts in the brain. The most consistently affected regions of the brain were cerebellum and brainstem. Skeletal muscles, and less frequently the heart, contained large intrasarcoplasmic bradyzoites typically without inflammation. Fifteen of the 22 birds tested positive using pan- Sarcocystis polymerase chain reaction. The sequence of the amplicon was most closely related to S. calchasi, and the 8 subtyped sequences had 100% homology with S. calchasi. This investigation demonstrated the transcontinental and North American spread of S. calchasi causing a disease outbreak in free-ranging rock pigeons, thus warranting increased surveillance in susceptible native columbids.

Early detection of wildlife morbidity and mortality through an event-based surveillance system

“…The WMME Alert System also detected increased admissions associated with an outbreak of neurological disease in rock pigeons ( Columba livia ) in the San Francisco Bay area in late winter/early spring of 2017 ( figure 3 c ) [ 35 ]. Meningoencephalitis and protozoal organisms were observed on post-mortem examination.…”

“…Meningoencephalitis and protozoal organisms were observed on post-mortem examination. Pan- Sarcocystis PCR identified Sarcocystis calchasi group infections in several of the pigeons and sequences detected in eight cases had 100% homology with S. calchasi [ 35 ]. This event demonstrated the emergence of this parasite in free-ranging birds in California and highlighted the importance of increased surveillance in susceptible native columbids.…”

“…citizen wildlife mortality event reporting), are important complements to targeted surveillance efforts in California (e.g. chronic wasting disease in cervids and white-nose syndrome in bats) through efficient monitoring for emerging threats across a broad range of species and geographies [ 40 ], especially species in disturbed environments [ 35 ]. The information generated through this system adds value to other general surveillance strategies through its ability to rapidly and efficiently detect threats that lead to illness and death in wild animals but do not necessarily result in conspicuous mortality events that would be detected through citizen reporting streams.…”

“…conjunctivitis in songbirds, trichomoniasis in doves, CDV in raccoons and petroleum contamination of marine birds were detected with support from this system's alerts, illustrating its use for monitoring trends in these diseases over time. The system also detected events that upon investigation were identified to be the result of emerging diseases in peridomestic and/or invasive species that present a threat to native wildlife [ 35 , 46 ]. Detecting anomalies in admissions associated with emerging diseases in wildlife illustrates this system's capacity to detect anomalous events associated with a novel threat.…”

High prevalence of Sarcocystis calchasi in racing pigeon flocks in Germany

“…Infections of S . calchasi have been recorded in Germany, the United States of America, and Japan [2,12–14], suggesting a worldwide distribution of the parasite.…”