Identification of risk factors associated with exposure to porcine respiratory and reproductive syndrome virus in pig farms from the state of Yucatan, Mexico.

Abstract

THE AIM OF THIS STUDY WAS TO IDENTIFY THE RISK FACTORS ASSOCIATED WITH THE PORCINE RESPIRATORY AND REPRODUCTIVE SYNDROME VIRUS IN PIG FARMS FROM THE STATE OF YUCATAN IN MEXICO. THIRTY SEVEN CONTINUOUS FLOW PIG FARMS WERE STUDIED. SIXTY ONE BLOOD SAMPLES WERE COLLECTED IN EACH FARM, AND THEN THE ENZYME LINKED IMMUNOSORBENT ASSAY (ELISA) FOLLOWED. THE RISK FACTORS WERE EVALUATED USING THE INFORMATION FROM A QUESTIONNAIRE ANSWERED BY THE OWNERS OR FARM MANAGER. A UNIVARIATE ANALYSIS (FISHER EXACT TEST) WAS CARRIED OUT IN ORDER TO EVALUATE THE ASSOCIATION BETWEEN RISK FACTORS AND THE HIGH PREVALENCE, (> 30%), FARMS AND THE LOW PREVALENCE ONES (< 30%). THE ASSOCIATION WITH P<0.25 VALUES WERE INCLUDED IN A LOGISTIC REGRESSION ANALYSIS. THE SIGNIFICANCE LEVEL WAS 10%. A SIGNIFICANT ASSOCIATION BETWEEN HIGH PREVALENCE FARMS AND THE REPLACEMENT SOW (P=0.04) AND PIG HOUSE EMPTYING (P=0.09) VARIABLES WAS FOUND IN THE LOGISTIC REGRESSION FINAL MODEL. THE FARMS WITH AN EXTERNAL REPLACEMENT SYSTEM HAD 6.70 GREATER PROBABILITY OF A PREVALENCE EQUAL OR HIGHER THAN 30% IN COMPARISON WITH THOSE THAT DID NOT. THE FARMS WITH PARTIAL EMPTYING HAD 7.99 GREATER PROBABILITY PROBABILITIES OF A PREVALENCE HIGHER THAN 30% IN COMPARISON WITH THOSE THAT DID NOT.