Intestinal Spirochetes in Poultry: The Hidden Threat to the Egg Industry and Human Health
Dr. Majed Al-Sayegh
4/ 10/ 2025
Intestinal Spirochetes in poultry are an emerging and neglected disease despite their significant economic impact. They primarily affect laying hens and breeders, causing chronic diarrhea, slow growth, reduced or delayed egg production, and poor egg quality.
The main causative agent is the bacterium Brachyspira pilosicoli, intermedia, and alvinipulli. These bacteria are Gram-negative, spiral-shaped, motile, and oxygen-tolerant. They multiply slowly in the large intestine, where they attach to cells, forming what is known as a “pseudobulb,” impeding absorption and leading to intestinal infections.
The disease is transmitted primarily via the fecal-oral route. Wild birds, rodents, and contaminated water play a pivotal role in spreading the infection, with multi-age pens being the most susceptible. Economic losses in the United Kingdom alone are estimated at £18 million annually, underscoring the global seriousness of the disease.
The zoonotic significance of the disease is growing, with documented cases of human infection with B. pilosicoli via contaminated meat or contact with poultry, particularly in poor environmental conditions or immunocompromised individuals. Symptoms include chronic diarrhea, abdominal pain, and rectal bleeding. Diagnosis is often difficult because symptoms are nonspecific, requiring bacterial cultures or molecular tests such as PCR.
Treatment primarily relies on antibiotics such as tiamulin and some macrolides, but bacterial resistance to these drugs is increasing due to genetic mutations and the blocking of growth promoters. This has prompted the search for alternatives such as probiotics (Lactobacillus), herbal supplements such as cinnamon, and fermented products, which have shown encouraging results. Although there are currently no commercial vaccines, recombinant proteins such as Bmp72 have shown promising results in trials.
Therefore, controlling the disease requires an integrated strategy that includes strict biosecurity, hygiene, the rational use of treatments, and the development of sustainable vaccines. From a One Health perspective, strengthening epidemiological surveillance and investing in research and development remain essential steps to protect the poultry industry and reduce health risks to humans.
