Intestinal roundworm infection in organic and alternative swine farms in the USA.

Swine parasites are a challenge for organic and alternative pig farmers and represent suboptimal animal health because use of chemical prophylaxis is not recommended. There is no comprehensive study of how prevalent gastrointestinal parasites are in organic or alternative pig farms across the USA. This study investigates prevalence, abundance, and intensity measures for three intestinal roundworm parasites (Ascaris suum, Oesophagostomum spp. and Trichuris suis) on organic and alternative swine farms by quantifying their eggs in pig feces, pastured soil, and bedding. Nine farms raising pigs in bedded facilities across four states (Iowa, Minnesota, Pennsylvania, and Wisconsin) were sampled, and analysis of parasite egg counts from feces indicate that 88.9%, 55.5%, and 44.4% of farms were infected with A. suum, Oesophagostomum spp. and T. suis, respectively. Prevalence, mean abundance, and mean intensity of eggs per gram (EPG) in feces for A. suum and T. suis were higher in growing and finishing pigs, whereas they were higher for Oesophagostomum spp. in finishing pigs and sows. Prevalence and abundance with A. suum eggs in feces were higher in organic certified farms, whereas abundance of Oesophagostomum spp. and T. suis was lower than those in alternative farms. Fewer eggs were recovered from soils than bedding samples, but their presence in both substrates confirmed that dispersal stages occur in farms. Overall, our results indicate that intestinal parasite infection across organic and alternative swine farms in the USA is common, and not surprising given that few options to control infection within organic regulations are available.