Factors associated with the presence of nematode and protozoa parasites in domestic pigs with outdoor access

An increasing number of swine producers in the United States are adopting non-intensive outdoor pig-rearing systems, which could facilitate parasite transmission given animal's contact with soil and other animal species. The two main objectives of this study were to determine the prevalence of gastrointestinal parasites in pigs raised with access to outdoor, non-concrete areas and to investigate the association between farm demographics and management factors, and detection of selected enteric pathogens on their occurrence. Fifteen farms were recruited between March 2024 and March 2025 across four USA states. Farms completed a questionnaire and fecal samples were collected and screened for parasite eggs/oocysts by parasitology tests and tested for relevant bacterial and viral enteric pathogens (rotaviruses, Salmonella spp., and Lawsonia intracellularis ) by PCR . A total of 137 fecal samples were collected from pigs aged 2 months to 12 years and the most prevalent parasites were coccidia and strongyles (81.75% and 44.53% of samples respectively). Out of 131 samples tested by PCR, 29.01% samples were positive for rotavirus A and 7.63% were positive for rotavirus B. Factors positively associated with the detection of nematodes were being older than 24 weeks and the existence of a veterinary client patient relationship. These findings highlight the diversity of gastrointestinal parasites in pigs raised in outdoor, non-concrete areas, as well as the importance of age-based risk assessment and basic biosecurity practices to improve health outcomes in alternative swine farms.