Chanthirasekaran Raju
Avian intestinal spirochetosis (AIS) is an enteric disease of laying hens caused by pathogenic Brachyspira species and is likely underrecognized in typical on-farm conditions. Despite India being a major egg-producing country, organized data on AIS in Indian poultry remain limited. This targeted investigation described Polymerase Chain Reaction (PCR) detection of Brachyspira spp., associated field observations, and preliminary species-level evidence in clinically suspected commercial layer flocks in South and North India. Cecal mucosal scrapings were collected from 59 recently deceased laying hens from 12 commercial farms (33 sheds; 25 to 105 weeks of age) and applied to FTA cards. Samples were screened by PCR targeting the Brachyspira 16S rRNA gene and the NADH oxidase (nox) gene; selected amplicons were sequenced and analyzed phylogenetically. Brachyspira spp. were detected in 83.3% of farms, 82% of sheds, and 67.8% of samples in this targeted investigation of clinically suspected flocks. Detection was numerically higher in older flocks, ranging from 37.5% in birds aged 25 to 40 weeks to 84.6% in birds aged 71 to 105 weeks; however, this age related trend was not statistically significant. PCR-positive flocks commonly exhibited loose droppings, wet litter, vent pasting, dirty, fecal-stained eggs (approximately 1 to 5%) of total eggs, and only modest reduction (3 to 5%) in egg production in about one-third of affected flocks. nox sequencing of selected PCR-positive samples identified sequences consistent with Brachyspira pilosicoli, Brachyspira intermedia, Brachyspira pulli, and Brachyspira alvinipulli, providing preliminary evidence of multiple Brachyspira spp. among sequenced samples.