Avian intestinal spirochaetosis: an emerging zoonosis

Abstract Intestinal spirochetes are detected in a wide range of mammalian and avian host species. and cause enteric disease, especially in swine and poultry. Although avian intestinal spirocheosis (AIS) is considered a growing and underestimated problem in poultry production systems, its occurrence and economic burden cannot be neglected. The causative agent of AIS is Brachyspira spp., particularly Brachyspira pilosicoli ( B. pilosicoli ), B. intermedia, and B. alvinipulli . They are Gram-negative spiral motile, oxygen-tolerant, and fastidious slow-growing anaerobes of the order Spirochaetes. The bacterium colonizes the lower gastrointestinal tract of most domestic and free-living birds. Layer and breeder chickens are most susceptible to Brachyspira spp. infection and present signs of chronic diarrhea, a low growth rate, delayed or reduced egg production, and poor egg quality. The zoonotic potential of B. pilosicoli is increasingly recognized. Humans can become infected via contact with the feces or meat of infected animals or food contaminated by food handlers. Patients with colonic spirochaetosis exhibit signs of diarrhea, rectal bleeding, and abdominal pain. Diagnosis is usually carried out through conventional isolation and identification as well as recent molecular detection techniques. Tiamulin and other macrolides are considered the gold standard for treating AIS. Unfortunately, resistance of bacteria to such treatments has emerged owing to the urgent need for the development of new interventions. Non-antibiotic interventions such as probiotics show promising results in preventing Brachyspira infection. There are no commercially available vaccines to prevent AIS. However, a recombinant vaccine against B. pilosicoli was recently developed in layer chickens. Here, the review discusses AIS in terms of etiology and pathogenesis, susceptibility and transmission, clinical picture in poultry, human infection, laboratory diagnosis, and prevention and treatment.