Porcine Swine Dysentery Study Guide

Overview and Clinical Importance

Swine dysentery (SD) is a severe mucohemorrhagic diarrheal disease of pigs caused by strongly beta-hemolytic spirochetes of the genus Brachyspira. The disease is characterized by inflammation limited to the large intestine (cecum and colon) and is most commonly observed in growing-finishing pigs. SD represents a significant economic concern in swine production due to mortality (up to 30% if untreated), reduced growth performance, and costs associated with treatment and control measures.

While Brachyspira hyodysenteriae has historically been the primary etiologic agent, two additional strongly beta-hemolytic species have been confirmed as causes of SD: Brachyspira hampsonii (North America and Europe) and Brachyspira suanatina (Scandinavia). These three species are distinguished from non-pathogenic or weakly pathogenic species by their strong beta-hemolysis on blood agar.

Etiology

Causative Agents

Brachyspira hyodysenteriae is a Gram-negative, motile, helically coiled (spiral-shaped), obligate anaerobic spirochete belonging to the family Brachyspiraceae. The organism was previously classified as Treponema hyodysenteriae and Serpulina hyodysenteriae. Key characteristics include 7-14 periplasmic flagella at each cell end that enable characteristic corkscrew motility through viscous environments.