Septicemia caused by Escherichia coli is a common disease of
calves, and to a lesser extent lambs, <1 wk old. It may present
with signs of acute septicemia or as a chronic bacteremia with
localization. Etiology and Epidemiology The disease is caused by
specific serotypes of E coli that possess virulence factors
enabling them to cross mucosal surfaces and produce bacteremia
and septicemia. However, the main determinant of the disease is
deficiency of circulating immunoglobulins as the result of a
failure in passive transfer of colostral immunoglobulin;
septicemic disease due to invasion by E coli occurs only in
immunoglobulin-deficient calves. Colisepticemia is seen during
the first week of life, most commonly at 2–5 days of age.
Chronic disease with localization can be seen up to 2 wk of age.
The disease is usually sporadic and is more common in dairy than
beef calves. Transmission and Pathogenesis Invasion occurs
primarily through the nasal and oropharyngeal mucosa but can
also occur across the intestine or