Bacterial diseases

Colisepticemia

Colisepticemia, also known as colibacillosis caused by Escherichia coli, is the commonest disease condition in ill-managed organized poultry units. E. coli is part of the normal healthy intestinal microflora in chickens as well as other animals but act as a pathogen under immunosuppressive conditions, poor nutrition and management or severe stress. The disease occurs either as an acute generalized fatal from or chronic debilitating from. The morbidity varies whereas mortality is 5-20% but may be higher when associated with other co-existing diseases like mycoplasmosis. The infectious agent is moderately resistant in the environment, but is susceptible to common disinfectants.

Infection spreads generally via feed and water but manual contamination of fertile eggs may lead to hatching of infected chicks. Transmission is also possible by inhalation and via fomites.

Symptoms and lesions: The clinical symptoms are distended abdomen and tendency to huddle. The chicks and growers may show higher mortality, ruffled feathers, diarrhoea, pasty vents, respiratory signs like coughing, sneezing, loss of appetite, poor growth, and omphalitis; whereas the adult and laying birds show variable symptoms including drop in egg production.

Significant post-mortem (PM) changes include air sacculitis, congested or pneumonic lungs, pericarditis, enlargement of liver and spleen, peritonitis, salpingitis, enteritis and presence of pseudo-membranes over visceral organs. Some strains of E.

Table- OIE classification of List A and B diseases

               Bacterial diseases                                                   Classification

coli are responsible for a condition called as coli-granulamatosis (Hjare's disease) characterized by the presence of granuloma in liver cecum, duodenum and mesentery.

Omphalitis or yolk sac infection is another common condition of hatchlings and chicks due to E. coli infection during the first week of hatch and may result in inflamed umbilicus, abnormal coloured unabsorbed yolk in the abdomen and peritonitis. Mortality rate may go up to 100%. Staphylococci, Pseudomonas and other opportunists may also be present as secondary infections.

Diagnosis: The diagnosis of coli infections is based on clinical symptoms, gross lesions and by the isolation of the organisms from heart blood, yolk sac and visceral organs by direct cultivation onto common media and differentiation on McConkey's agar medium wherein the E. coli colonies due to lactose fermentation look pink to brick red in colour.

Prevention and control: Good hygiene, maintenance of high standards of hatchery flock management including good quality feed and water, provision of best possible brooding conditions. Poultry owners should be educated to procure chicks from well managed flocks and hatcheries and to control the predisposing factors and infections. Antibiotics in consultation with veterinarians should be given in drinking water.