Dealing with the rise of Swine Dysentery

Swine Dysentery, a disease caused by Brachyspira hyodysenteriae and characterized by the onset of catarrhal hemorrhagic diarrhea, is experiencing a major re-emergence in many countries worldwide.

UNMASKING B. hyodysenteriae

MORPHOLOGY AND SURVIVAL

Brachyspira hyodysenteriae is an anaerobic gram-negative spirochete with helical shape and 7-14 periplasmic flagellums. Its flagellums facilitate the movement on the surface of the colon mucosa, which is rich in calciform cells and mucus.

For dysentery to occur, it is necessary the infection by B. hyodysenteriae, B. suanatina or B. hampsonii, although this is not sufficient to trigger the disease. Other factors such as the interaction with the microbiota and the diet have also an impact.

The presence of mucus favors its survival and proliferation by creating an anaerobic environment, and a source of nutrition and protection against intestinal flow.

The nox gene encodes for the enzyme NADH oxidase that protects the bacteria from to oxygen toxicity.

There are variations in the level of pathogenicity of the bacteria. Depending on the microbiota and diet or the interactions with the characteristics of the present strain, the disease can manifest or not. Therefore, the circulation of low pathogenic strains makes difficult the implementation of a prevention program.

TRANSMISSION

Swine Dysentery is a disease with great impact on domestic pigs, although it also affects wild species, with infection occurring via the fecal-oral route.

The bacteria can infect and be eliminated through the feces of other species such as
ducks, geese, chickens, gulls, dogs and especially rodents, which can excrete the bacteria for long periods of time (up to 6 months).

Despite the apparent success in keeping Swine Dysentery under control, it remains a major problem for many producers, and several factors have contributed to the re-emergence of this disease: