Colibacillosis is a bacterial disease that is caused by Escherichia coli, better known as E. coli. Although E. coli is part of the normal bacteria of the gut in humans and animals, some strains are capable of causing severe disease. There are usually two distinct manifestations of an E. coli infection in chickens: severe infections and chronic, mild to moderate infections.
Symptoms can include listlessness, ruffled feathers, labored breathing and coughing. There can also be indirect symptoms from secondary infections spurred by the initial E. coli infection. Severely infected birds may exhibit diarrhea, swelling, and congestion of the liver and spleen. These bacteria can sometimes cause a navel infection in newly hatched chicks.
Secondary infections in the respiratory tract are common in crowded, dusty and high-ammonia environments. Most MG or viral infections of the respiratory tract result in a full recovery within two weeks of infection, but a secondary E. coli infection could be fatal due to pneumonia, inflammation of the air sac or a bacterial infection of the blood.
Can it spread?
Chickens infected with E. coli should be removed from the flock to prevent further spreading of the disease. Young chickens are most susceptible, especially if their living conditions are crowded, dusty and contaminated with feces and ammonia. Navel infections result from fecal contamination of hatching eggs.
To reduce the risk of a Colibacillosis infection, keep your chickens’ living area dust-free and clear of feces and ensure that there is sufficient space for each chicken. Also, do not use visibly dirty eggs as hatching eggs because this could perpetuate the disease. Efforts to “clean” dirty eggs could result in eggshell damage and increased shell penetration by bacteria.
Colibacillosis responds in varying degrees to antibiotic treatment with tetracyclines and sulfa drugs. Treatment should last a minimum of five days before evaluating improvement in symptoms.
About the Authors: Dr. Jose A. Linares, DVM, ACPV, is the Resident Director of the Texas Veterinary Medical Diagnostic Laboratory, Poultry Diagnostic Laboratory in Gonzales, TX. Dr. John El-Attrache, PhD, is an Assistant Professor in the Department of Veterinary Pathobiology in the College of Veterinary Medicine at Texas A&M University.