Fetal losses associated with PRRSV, PPV, and PCV2 detection

Abstract

This study aimed to investigate the prevalence of porcine reproductive and respiratory syndrome virus (PRRSV),porcine parvovirus (PPV), and porcine circovirus type 2 (PCV2) infections associated with fetal losses in 10 commercialswine herds in Thailand. Samples were collected from 100 sows and included 25 aborted fetuses, 35 mummified fetuses,and 40 stillborn piglets. The average parity number of the sows was 2.8 ± 2.4, ranging from 0 to 11. Fetal age wasdetermined based on either the day of abortion or estimated using crown-rump length, and categorized as <70 days or≥70 days. Organs from each case were pooled, homogenized, and tested for PRRSV (n = 100) using reverse transcriptionPCR, and for PPV and PCV2 (n = 60 each) using conventional PCR. PRRSV, PPV, and PCV2 were detected in 66.0%(66/100), 0% (0/60), and 93.3% (56/60) of samples, respectively. Specifically, PRRSV was identified in 52.0% (13/25) ofaborted fetuses, 62.9% (22/35) of mummified fetuses, and 77.5% (31/40) of stillborn piglets (P = 0.096). PCV2 wasdetected in 94.1% (16/17), 96.7% (29/30), and 84.6% (11/13) of the same groups, respectively (P = 0.343). Co-infectionwith PRRSV and PCV2 was observed in 60.0% (36/60) of cases, specifically in 13.3% of aborted (n = 8), 30.0%of mummified (n = 18), and 16.7% of stillborn (n = 10) fetuses. No significant differences in PRRSV or PCV2 detectionwere found based on sow parity or fetal age group (P > 0.05). Among PRRSV-positive samples, genotypes 1, 2, andmixed types accounted for 30.3%, 37.9%, and 31.8%, respectively (P = 0.728). Interestingly, 92.3% of stillbornpiglets tested positive for either PRRS or PCV2, while only 7.7% were free from all the viruses investigated. Similarly,all mummified fetuses (100%) were infected with either PRRS or PCV2, with none testing negative for the examinedviruses. Among aborted fetuses, 94.1% were positive for either PRRS or PCV2, whereas only 5.9% were virus-free. These results highlight a strong association between PRRSV and PCV2 infections and fetal losses,underscoring the importance of targeted surveillance and control measures in Thai swine herds.