Epidemiological surveillance and economic impact analysis of different porcine reproductive and respiratory syndrome virus infection statuses in 23 breeding pig farms in Hubei, China

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) has emerged as a significant threat to the pig farming industry worldwide, resulting in considerable economic losses. However, few reports detail its economic impact on the pig farming sector. A study was conducted on 23 breeding pig farms in Hubei Province from January 2021 to December 2023, and the PRRSV infection status and associated economic losses were monitored to address this gap. PRRSV antigens and antibodies were identified through enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Additional monthly production data and weaning costs were gathered. The Kruskal-Wallis nonparametric test was used to assess the differences in production efficiency and weaning costs across various PRRSV infection statuses. Dunn’s test was used to compare multiple groups. The parameter distributions of various variables were determined via @RISK (V. 8.5.2) software. Models were developed to evaluate the economic impact of PRRSV infection status on breeding pig farms and assess the losses from a PRRSV outbreak in either provisional PRRSV-negative or PRRSV-positive stable farms. A total of 754 months of monitoring was conducted across 23 breeding pig farms, which included 131 months (17.37%) classified as PRRSV provisional negative, 298 months (39.52%) as PRRSV-positive stable, and 325 months (43.11%) as PRRSV-positive unstable. The production efficiency and weaning costs were similar between provisional PRRSV-negative farms and PRRSV-positive stable farms, revealing no significant differences. However, these metrics varied significantly compared with those of PRRSV-positive unstable farms. With respect to provisional PRRSV-negative farms, PRRSV-positive stable farms and unstable farms faced additional annual losses of ¥3,135.17 and ¥4,898.79 per sow, respectively. Compared with PRRSV-positive stable farms, PRRSV-positive unstable farms incurred an extra annual loss of ¥1,763.62 per sow. Upon a PRRSV outbreak on a swine farm, followed by a return to preoutbreak conditions, the average economic loss per sow on provisional PRRSV-negative farms is approximately ¥3,061.21. Conversely, PRRSV-positive stable farms face an average loss of approximately ¥508.42 per sow. This study provides a systematic evaluation of the economic impact of PRRSV on Chinese pig farms, offering data to support the quantitative assessment of economic losses stemming from PRRSV within the domestic pig farming industry.