Although losses in birds due to bacterial toxins are not of great economic importance, they do occasionally result in heavy losses in a particular flock. The main organism affecting poultry is Clostridium botulinum. No significant lesions are found in botulism poisoning and a positive diagnosis is usually based on identification of the organism and its toxin.
Botulism is caused by the toxin produced from the C. botulinum organism under anaerobic conditions. C. botulinum is a saprophyte found in soil and dirt and can also be found in intestinal contents and feces. The mere presence of the organism is sufficient to cause disease or to be of diagnostic significance. Growth of the organism, in anaerobic conditions, results in the production of toxins. Botulism can result from birds eating carcasses of birds which have died from the disease and also fly larvae from such carcasses. The toxins present in the meat are ingested by larva rendering them extremely poisonous. Symptoms may appear within a few hours to a day or two after contaminated feed is eaten. The common symptom noted is paralysis, with the leg and wing muscles first affected. If the neck muscles are affected the head hangs limp, hence the name 'limberneck' which has been used to refer to the disease. In mild cases, leg weakness, ruffled feathers and soft pasty feces may be noted. The severity of the disease depends on the amount of toxin consumed. However, death usually occurs as this toxin is very potent. Losses in birds are most commonly due to type A and C toxins. Type A, is common in the mountainous regions of North and South American, while type C is world-wide in distribution.
For many years, a disease of wild ducks and other aquatic birds was common in the western part of North America. It is now known that this is due to botulism poisoning. Insect larvae in an aquatic environment may die as the result of anaerobic conditions caused by decaying vegetation. When these larvae are eaten by birds, botulism organisms invade tissues and produce toxins. Prevention relates to proper management procedures that eliminate dead and decomposed carcasses around a poultry house. A good rodent and fly control program is also essential as is screening of the building to eliminate entry of wild birds.
Was this article helpful?