The lower small intestine is generally affected. Lesions are histologically similar to those seen in coronaviral enteritis. E. coli enterotoxicosis occurs in calves up to 6 days of age. Diarrhea results from the release of thermostabile enteroxin that produces profound hypersecretion from enterocytes without significantly damaging the epithelium. These bacteria damage the mucosa through invasion and the production of enterotoxins.
Infection frequently results in septicemia.
Infect calves in the first three weeks of life. These extracellular protozoa attach to the epithelium of the small and large intestine and displace the microvilli. Diseases caused by viruses. Australian Vet Journ. 71, No. 2, 33-41, February 1994.