Porcine Edema Disease Study Guide

Overview and Clinical Importance

Edema disease (also known as gut edema, bowel edema, or E. coli enterotoxemia) is a peracute, often fatal toxemia affecting recently weaned pigs. The disease is caused by Shiga toxin 2e (Stx2e)-producing Escherichia coli strains that colonize the small intestine and produce a potent cytotoxin. First reported in 1938, edema disease has become increasingly common with intensive swine production practices and represents a significant economic concern in modern pig farming, with mortality rates reaching 50-90% in affected pigs.

Despite being classified as an enteric disease, the hallmark clinical signs are neurologic, caused by vascular damage in the central nervous system. The disease typically occurs 5-14 days post-weaning and primarily affects the healthiest, fastest-growing pigs in a group, often presenting as sudden death without premonitory signs.

Etiology and Pathogenesis

Causative Agent

Edema disease is caused by specific pathotypes of Escherichia coli that possess two critical virulence factors: F18 fimbriae (for intestinal attachment) and Shiga toxin 2e (Stx2e) production. These are distinct from enterotoxigenic E. coli (ETEC) that cause post-weaning diarrhea.