Prevalence and risk factors for lawsonia intracellularis, brachyspira hyodysenteriae and Salmonella spp. in finishing pigs in Polish farrow-to-finish swine herds

Abstract

The aim of the study was to estimate the herd-level, within-herd prevalence, the frequency of mixed infections and risk factors for L. intracellularis, B. hyodysenteriae and Salmonella spp. in selected farrow-to-finish Polish pig herds. A total of 254 pooled fecal samples were collected from 9 to 24 week-old pigs in 70 herds. Real time PCR for detection of L. intracellularis and B. hyodysenteriae was performed. For Salmonella spp. bacteriological examination was performed. The herd-level prevalences of L. intracellularis, B. hyodysenteriae and Salmonella spp. among examined herds were 65.7%, 1.4% and 8.6%, respectively. The within-herd prevalences (in positive herds) for L. intracellularis, B. hyodysenteriae and Salmonella spp. were 51.5%, 75.0% and 30.4%, respectively. All herds with diarrhea observed during sampling were infected with L. intracellularis and 60% of herds with no diarrhea at the moment of sampling were infected with L. intracellularis (p=0.035). In herds with more than 200 sows the prevalence of Salmonella spp. was significantly higher compared to herds with less than 200 sows (p=0.027). In herds where all-in/all-out (AIAO) was respected, prevalence of L. intracellularis was significantly lower than in herds where this rule was not kept (p=0.024). Obtained results confirm that L. intracellularis is the major cause of bacterial diarrhea in finishing pigs. The present study identified AIAO and herd size as a risk factor, at the herd level, for L. intracellularis and Salmonella spp., respectively.