Prevalencia y factores de riesgo asociados con el virus del síndrome reproductivo y respiratorio porcino en sementales de granjas porcinas en el sureste de México

the objectives of this study were to estimate the prevalence of and to determine some risk factors associated with the porcine reproductive and respiratory syndrome (prrs) virus in boars from pig farms in yucatan, mexico. the study was carried out in 30 farms with 28 to 2,000 sows and different levels of technology. on arrival, boars were kept for an adaptation period to the farm conditions and management. natural mating, artificial insemination or both techniques were used. commercial feed was provided to the boars. a cluster cross-sectional study was carried out from september 2005 to february 2006, and 170 boars were sampled. the presence of antibodies and virus particles was determined using elisa and rt-pcr (reverse transcriptase- polymerase chain reaction) tests respectively. fifty six out of 170 boars were positive to elisa test, 21 to rt-pcr and 67 to one or both tests. boar prevalence was 39.4% (67/170) and within farm varied from 0 to 100%. twenty one farms (70%) had at least one elisa positive animal, 13 positives to rt-pcr test (43.3%) and 25 (83.3%) to one or both tests. the risk of a prrs virus positive boar was 3.6 times greater in the positive farms and 2.6 when no diagnostic tests were carried out before introducing the boar to the farm. farms using the boars for estrus detection had 7.0 times greater risk of a prrs virus seropositive boar.