Risk association of Lawsonia intracellularis in commercial swine farms

Lawsonia intracellularis and Brachyspira species are important enteric pathogens in commercial pig farming. Despite their importance, there is little information on the epidemiology and risk factors of these pathogens in Vietnam. Therefore, this study investigated the percentage of L. intracellularis, B. pilosicoli, and B. hyodysenteriae across 18 commercial pig farms in Vietnam and analyzed risk factors for L. intracellularis infection. Fecal samples were collected from pigs in three age groups, and bacterial DNA was analyzed using quantitative PCR. The study found a 100% percentage of L. intracellularis at the farm level, with 90.74% of individual samples testing positive. B. pilosicoli was detected in 27.78% of farms, while B. hyodysenteriae was not detected in any samples. Risk factor analysis revealed thatpost weaning diarrhea, direct contact between pig batches, and the presence of rats were significantly associated with L. intracellularis infection. Post-weaning frequently experience diarrhea had a 1.8 times higher risk than non-diarrhea, and direct contact between pigs increased infection risk by 10.29 times. The presence of rats also contributed to higher infection rates. These findings emphasize the importance of improved biosecurity, and effective management practices to control the spread of L. intracellularis in Vietnamese pig farms.