Colibacillosis

In poultry: rising mortality, weight loss and falling egg production, with fibrinous airsacculitis, pericarditis and perihepatitis at necropsy. Other forms include yolk-sac infection with chick deaths, salpingitis and peritonitis in hens, cellulitis, swollen head syndrome, arthritis and osteomyelitis, and coligranulomas in liver, duodenum, caecum and mesentery. In calves aged 1-4 days: watery diarrhoea with dehydration, acidosis and electrolyte imbalance; calves that are depressed, anorexic and febrile often have E. coli septicaemia.

Colibacillosis is disease caused by pathogenic Escherichia coli. In poultry the agent is avian pathogenic E. coli (APEC), an extraintestinal pathotype that can live harmlessly in the gut and airways and invades through damaged tracheal or intestinal lining when birds are stressed. Fimbrial adhesins (type 1, P and S), siderophore iron-uptake systems, and protective capsule, outer membrane proteins and lipopolysaccharide let it resist complement and phagocytes and spread through the blood, causing airsacculitis, perihepatitis, pericarditis and septicaemia. In newborn calves, E. coli carrying the K99 (F5) adhesin attaches to the intestinal mucosa and produces enterotoxin, leading to watery diarrhoea, dehydration and electrolyte imbalance.

Avian colibacillosis affects chickens, turkeys, ducks and other birds and is a leading cause of poultry losses worldwide. It often follows infectious bronchitis, Newcastle disease, avian influenza or Mycoplasma infection, or poor housing: ammonia damages airway cilia and inhaled faecal dust is a confirmed route. Contaminated feed, water and eggs spread it, and vertical transmission from breeders is documented. Resistance to almost all antibiotic classes, including colistin and carbapenems, has been reported, and some APEC share virulence genes with human extraintestinal E. coli, raising possible zoonotic concern. In calves, K99 E. coli is one of the four most important causes of neonatal diarrhoea worldwide, typically at 1-4 days old.

In poultry, coligranuloma lesions resemble leukosis tumours, and colisepticaemia is often compounded by viral or Mycoplasma infection that must be identified. In calves, rotavirus, coronavirus and Cryptosporidium parvum cause similar diarrhoea, but usually at 1-3 weeks of age, whereas K99 E. coli typically strikes in the first four days of life.

Air sacs, lungs, pericardium, liver capsule, yolk sac, oviduct, peritoneum, skin, joints and bone, blood; small intestine in calves

Poultry: good litter and ventilation to limit ammonia and dust, clean chlorinated water, egg fumigation soon after laying, control of predisposing infections, commercial live or inactivated vaccines. Calves: colostrum management and dam vaccination.

Poultry mortality reaches up to 20% overall and up to 53.5% in young chicks; coligranuloma spreading through a flock can kill up to 75%. Antimicrobial resistance often makes treatment fail. Neonatal calf diarrhoea has a case fatality risk of about 4.9%.