Molecular identification and biological characterization of <i>Eimeria columbarum</i> from domestic pigeons ( <i>Columba livia domestica</i> ) in Guangdong, China

Pigeon coccidiosis caused by <i>Eimeria</i> spp. is an important veterinary disease with a significant economic impact on the pigeon industry. Preventive measures for <i>Eimeria columbarum</i> in pigeons have been hampered by the lack of extensive genetic, morphological, and biological data on the oocysts. In this study, we examined the prevalence and identity of <i>Eimeria</i> spp. in domestic pigeons from seven cities in Guangdong Province, China. Data show that coccidiosis was prevalent in domestic pigeons in Guangdong Province, with an overall <i>Eimeria</i> spp. detection rate of 73.4%. Five <i>Eimeria</i> species were identified, including <i>E. columbarum</i> (73.4%), <i>Eimeria kapotei</i> (25.6%), <i>Eimeria labbeana</i> (19.6%), <i>Eimeria duculai</i> (19.6%), and <i>Eimeria tropicalis</i> (6.7%). We obtained single oocyst-derived lines of the dominant <i>E. columbarum</i> from fecal specimens. <i>E. columbarum</i> oocysts measured 20.06 ± 0.69 μm × 18.63 ± 1.03 μm, and sporocysts measured 10.29 ± 0.82 μm × 85.38 ± 0.46 μm. In infection experiment using obtained <i>E. columbarum</i> isolates, 60-day-old coccidia-free pigeons exhibited a prepatent period of 105 h and patent period of 9-10 days followed by severe diarrhea, depression, anorexia, and emaciation. Endogenous development of the parasite was observed mainly in the cytoplasm of epithelial cells in the duodenum, jejunum, ileum, and rectum. Two generations of meronts developed on days 3 and 4 after infection, respectively, while gamont and gamete developed on day 5 after infection. The morphological, genetic, and biological data are expected to be useful in elucidating the biological characterization of pigeon coccidiosis to develop measures against the treatment and containment of this disease.