Porcine Glaesserella parasuis Infection – NAVLE Study Guide

Overview and Clinical Importance

Glässer's disease is a severe, systemic infectious disease of pigs caused by Glaesserella parasuis (formerly Haemophilus parasuis). The disease is characterized by fibrinous polyserositis, polyarthritis, and meningitis. It primarily affects young pigs in the nursery phase (4-8 weeks of age) and represents one of the most economically significant bacterial diseases in modern swine production worldwide.

The disease was first described in 1910 by Glässer, and the organism was first isolated in 1922. G. parasuis is a Gram-negative, pleomorphic, fastidious rod belonging to the family Pasteurellaceae. It requires NAD (V factor) but not hemin (X factor) for growth, distinguishing it from Haemophilus influenzae. The organism is ubiquitous in swine populations globally and colonizes the upper respiratory tract of healthy pigs within the first days of life.

Etiology

Organism Characteristics

Glaesserella parasuis is a small, Gram-negative, pleomorphic bacterium. It is non-hemolytic, non-motile, and microaerophilic. The organism grows on chocolate agar or blood agar as satellite colonies near a staphylococcal nurse streak (providing NAD). Colonies are small and translucent, typically appearing within 24-48 hours of incubation.