The most common viral infections that can cause swine reproductive problems

Abstract

Many viruses are responsible for the reproductive failure in sows and gilts, especially in countries with intensive pig production. The most important viral infectious agents are Aujeszky´s disease virus (ADV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine parvovirus (PPV) and porcine circovirus type 2 (PCV2). The presence of these viruses can cause fetal death, abortions, mummified and stillborn piglets, increased number of neonatal deaths or return to oestrus. Contaminated boar semen can also serve as a source of infection on the farm. The objective of this study was to analyze the presence of ADV, PRRSV, PPV and PCV2 in the tissue of aborted fetuses and placenta of sows and PRRSV in boar semen for the five-year period (2012-2017). The specimens originated from Vojvodina Province, Serbia. In total, 150 samples of aborted fetuses were submitted to the lab and 445 different analyses were performed in 150 samples (80 virus isolations of ADV, 78 virus isolations of PPV, 52 PCR analyzes of ADV, 41 PCR analyzes of PPV, 133 RT-PCR analyzes of PRRSV and 61 PCR analyzes of PCV2. PRRSV was detected in 4.51% (6/133) of tested specimens, while 1.64% (1/61) samples were positive for PCV-2. Neither ADV nor PPV were isolated on cell culture tissue or identified by PCR. During the same period, 16 samples of boar semen were examined on the presence of PRRSV and no evidence of this viral pathogen was identified. The number of detected positive cases is probably underestimated due to several factors: absence of data for the abortions in backyard pigs, lower sensitivity of classical virological methods comparing to molecular techniques, low quality of analyzed samples and only sporadic testing of boar semen for the artificial insemination. The authors of this article concluded that more intensive laboratory analyses should be conducted with the aim to identify and control the viral pathogens in pig production systems.