Very Low Seroprevalence of Porcine Reproductive and Respiratory Syndrome among Backyard Pigs in Leyte Province and Factors associated with S/P Ratios

orcine Reproductive and Respiratory Syndrome (PRRS) is a viral disease that causes significant production and economic losses to swine raisers. To estimate the seroprevalence of PRRS in pigs from the backyard and small-hold farms in the province of Leyte, Philippines, a total of 384 pigs were sampled at random from 11 localities and their sera were tested for PRRS antibody using indirect enzyme-linked immunoassay. Univariable and multivariable regression analyses were performed to determine the factors associated with the S/P ratios. Results revealed that the true seroprevalence for PRRS in backyard pigs was 0.28% (0.0001 to 0.0155, 95% CI) and the true herd-level seroprevalence was 1.02% (0.0005 to 0.1588, 95% CI). Factors significantly associated with the S/P ratios were: Large White (breed) (adjusted β = 0.22, p = 0.0014), the presence of goats (adjusted β = -0.63, p < 0.0001) in farm vicinity, disposing wastes to bodies of water (adjusted β = 0.27, p < 0.0001) and separating sick animals (adjusted β = 0.34, p < 0.0001). The very low seroprevalence in the backyard and small-hold pig farms may indicate a low prevalence of PRRS in the province. Practices in backyard farms like disposing of pig wastes to water bodies and separating or moving sick animals were present and may promote the spread of the virus and pose higher risks when future disease outbreaks occur. It is recommended that the government impose proper waste management on backyard swine farms to prevent the spread of PRRS and other economically important swine diseases.