Fomites might be responsible for virus introduction in swine farms, highlighting the importance of implementing practices to minimize the probability of virus introduction. The study’s objective was to assess the efficacy of different combinations of temperatures and holding-times on detecting live PRRSV and PEDV on surfaces commonly found in supply entry rooms in swine farms. Two PRRSV isolates (MN 184 and 1-4-4 L1C variant) and one PEDV isolate (NC 49469/2013) were inoculated on cardboard and aluminum. An experimental study tested combinations of four temperatures (20°C, 30°C, 40°C, and 50°C) and six holding-times (15 minutes, 60 minutes, 6 hours, 12 hours, 24 hours, and 36 hours) for the presence of the viruses on each surface type. After virus titration, virus presence was assessed by assessing the cytopathic effects and immunofluorescence staining. The titers were expressed as log₁₀TCID₅₀/ml, and regression models; half-lives equations were calculated to assess differences between treatments and time to not detect the live virus. The results suggest that the minimum time that surfaces should be held to not detect the virus at 30°C was 24 hours, 40°C required 12 hours, and 50°C required 6 hours; aluminum surfaces took longer to reach the desired temperature compared to cardboard. The results suggest that PRRSV 1-4-4 L1C variant had higher half-lives at higher temperatures than PRRSV MN 184. In conclusion, time and temperature combinations effectively decrease the concentration of PRRSV and PEDV on different surfaces found in supply entry rooms in swine farms.

This study evaluated influenza A virus (IAV) detection and genetic diversity over time, specifically at the human–swine interface in breeding and nursery farms. Active surveillance was performed monthly in five swine farms in the Midwest United States targeting the employees, the prewean piglets at sow farms, and the same cohort of piglets in downstream nurseries. In addition, information was collected at enrollment for each employee and farm to assess production management practices, IAV vaccination status, diagnostic procedures, and biosecurity. Farm employee and swine samples were screened by IAV reverse transcription real-time polymerase chain reaction (RT-rtPCR), followed by IAV subtyping RT-rtPCR and whole genome sequencing on PCR-positive samples. This study showed higher positivity of IAV RNA detection in nursery pigs compared to prewean pigs, and more whole genome sequences were also obtained in the nursery phase. Surveillance of farm employees revealed two detections of H3N2 representing the 2022–2023 human IAV season, confirming the presence of influenza in farm employees while present at work, and thus highlighting the importance of biosecurity measures at the human–swine interface. This study highlights the importance of routine active surveillance to understand the dynamics of IAV at the farm level in both farm employees and swine.

Understanding how sample type may influence the probability of influenza A virus (IAV) sequencing and isolation success can help improve the use of diagnostic tests and refine surveillance strategies in swine populations. The objective of this study was to evaluate the probability of success for IAV hemagglutinin (HA) and neuraminidase (NA) Sanger sequencing and virus isolation in Madin–Darby Canine Kidney (MDCK) cells across different porcine sample types submitted to the Iowa State University Veterinary Diagnostic Laboratory (ISU VDL) from 2018 to 2024. Antemortem and postmortem sample types were selected and analyzed based on reverse transcription real-time polymerase chain reaction (RT-rtPCR) cycle threshold (Ct) values. The Ct values corresponding to 95%, 75%, and 50% probabilities of sequencing or virus isolation success were determined for each sample type. For antemortem samples, a 95% probability of success for HA Sanger sequencing on nasal swabs exhibited a Ct value of 27.8 from 1046 samples and 23.6 for NA sequencing based on 66 nasal swabs. Using oral fluids, HA and NA Sanger sequencing success was at Ct values of 27.3 from 3446 samples and 22.1 from 137 samples, respectively. For postmortem samples, lung tissue had the highest number of sequences for the HA and NA, with Ct values of 25.7 and 21.5, respectively. For a 95% probability of successful virus isolation, nasal swabs demonstrated a Ct value of 21.1 from 647 samples, while lungs had a Ct value of 18.7 from 5892 samples. This study determined that nasal swabs and lung tissue had the highest probability of IAV gene sequencing and virus isolation success, while oral fluids, a common swine diagnostic sample type that is easy to collect and welfare-friendly, can be effective for gene sequencing when using lower IAV RT-rtPCR Ct values, i.e., ≤27.3. These results provide practical expectations for successful IAV HA and NA gene sequencing and virus isolation at 95%, 75%, and 50% probabilities based on sample type and RT-rtPCR Ct values to improve diagnostic testing strategies in swine populations.

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), a major challenge for the swine industry, can be transmitted both vertically and horizontally. Common sample types, including processing fluid, serum, and family oral fluid, can neither determine whether PRRSV infection originates vertically or horizontally nor directly reflects the sow’s PRRSV status. At around 90 days post live-virus inoculation (LVI), 555 sows were sampled by Tonsil-oral-scrubbing (TOSc) 2 weeks pre-farrowing and tested for PRRSV RNA. From these, 59 PRRSV-positive sows, and 88 PRRSV-negative sows matched by parity were conveniently selected. TOSc from sows, blood swabs from live piglet, and tongue fluid (TF) plus serum from dead piglet were collected individually from all study litters within 12 h post-farrowing. The pre-farrowing TOSc samples had significantly higher PRRSV positivity than TF, serum and blood swab pools, while dead piglet serum had significantly lower mean Ct values than all other sample types. TOSc samples had 25% positive predictive value (PPV) for “live litter” PRRSV status while the pre-farrow and post-farrow TOSc had 87.2% and 89.0% negative predictive value (NPV), respectively. In conclusion, we characterized PRRSV RNA detection among all sub-populations within a litter with easy-to-use TOSc samples and neonatal litter samples, suggesting the occurrence of vertical transmission 90 days post-LVI in sows. TOSc samples from sows had low PPV and high NPV for their respective litter’s PRRSV status.