Monthly Archives: November 2017

Porcine reproductive and respiratory syndrome virus (PRRSv) causes substantial economic impact due to significant losses in productivity. Thus, measuring changes in farm productivity before and after PRRS infection enables quantifying the production and economic impact of outbreaks. This study assessed the application of exponentially weighted moving average (EWMA), a statistical process control method, on selected production data (number of abortions, pre-weaning mortality rate and prenatal losses) to supplement PRRS surveillance programs by detecting significant deviations on productivity in a production system with 55,000 sows in 14 breed-to-wean herds in Minnesota, U.S.A. Weekly data from diagnostic monitoring program (available through the Morrison’s Swine Health Monitoring Project) implemented on the same herds was used as reference for PRRS status. The time-to-detect, percentage of early detection of PRRSv-associated productivity deviations, and relative sensitivity and specificity of the production data monitoring system were determined relative to the MSHMP. The time-to-detect deviations on productivity associated with PRRS outbreaks using the EWMA method was -4 to -1 weeks (interquartile range) for the number of abortions, 0-0 for preweaning mortality and -1 to 3 weeks for prenatal losses compared to the date it was reported in the MSHMP database. Overall, the models had high relative sensitivity (range 85.7-100%) and specificity (range 98.5%-99.6%) when comparing to the changes in PRRS status reported in the MSHMP database. In summary, the use of systematic data monitoring showed a high concordance compared to the MSHMP-reported outbreaks indicating that on-farm staff and veterinary oversight were efficient to detect PRRSv, but can be more efficient if they were monitoring closely the frequency of abortions. The systematic monitoring of production indicators using EWMA offers opportunity to standardize and semi-automate the detection of deviations on productivity associated with PRRS infection, offering opportunity to early detect outbreaks and/or to quantify the production losses attributed to PRRS infection. Silva GS, Schwartz M, Morrison RB, Linhares DCL; Monitoring breeding herd production data to detect PRRSV outbreaks; Prev Vet Med. 2017 Dec 1;148:89-93. doi: 10.1016/j.prevetmed.2017.10.012. Epub 2017 Oct 26. PMID: 29157378 [PubMed – in process] PMID: 29157378 DOI: 10.1016/j.prevetmed.2017.10.012 Read the full article here: https://www.aasv.org/members/only/BreedingHerdData.pdf

Porcine reproductive and respiratory syndrome virus (PRRSv) outbreaks cause significant financial losses to the U.S. swine industry, where the pathogen is endemic. Seasonal increases in the number of outbreaks are typically observed using PRRSv epidemic curves. However, the nature and extent to which demographic and environmental factors influence the risk for PRRSv outbreaks in the country remains unclear. The objective of this study was to develop risk maps for PRRSv outbreaks across the United States (U.S.) and compare ecological dynamics of the disease in five of the most important swine production regions of the country. This study integrates spatial information regarding PRRSv surveillance with relevant demographic and environmental factors collected between 2009 and 2016. We used presence-only Maximum Entropy (Maxent), a species distribution modeling approach, to model the spatial risk of PRRSv in swine populations. Data fitted the selected model relatively well when the modeling approach was conducted by region (training and testing AUCs

Porcine epidemic diarrhea virus (PEDV) is an enteric disease of swine that has emerged as a worldwide threat to swine herd health and production. Substantial research has been conducted to assess viability of the virus on surfaces of vehicles and equipment, in feed and water, and on production building surfaces, but little is known about the persistence in PEDV-infected carcasses and effective disposal methods thereof. This study was conducted to quantify the persistence of PEDV RNA via quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) at various time-temperature combinations and in infected piglet carcasses subjected to composting. Although this method does not distinguish between infectious and noninfectious virus, it is a rapid and sensitive test to evaluate materials for evidence of virus genome. Results In the first study, PEDV was suspended in cell culture media at 1 × 105 TCID50 per sample (1 mL sample size) and subjected to various time and temperature combinations in triplicate including temperatures of 37, 45, 50, 55, 60, 65, 70 °C and exposure times of 0, 1, 2, 3, 4, 5, 7, and 14 days. At all temperatures, viral RNA copies declined over time, with the decline most marked and rapid at 65 and 70 °C. Detectable RNA did persist throughout the trial in all but the most extreme condition, where two of three samples incubated at 70 °C yielded undetectable viral RNA after 14 days. In the second study, PEDV-infected piglet carcasses were subjected to two cycles of composting lasting 36 and 37 days, respectively, for a total compost time of 73 days. Composting was performed in triplicate windrow sections housed inside biosecure, climate-controlled rooms using insulated bins designed to represent a continuous windrow compost pile. Temperatures reached 35-57 °C for 26 days of cycle 1 and 35-45 °C for 3 days of cycle 2. Samples consisting of carbon material with or without decomposed tissue as available per sample site collected at ten locations throughout the cross-section of each windrow section following the primary and secondary compost cycles yielded no detectable viral RNA. Conclusions Composting appears to be an effective disposal method for PEDV-infected piglet carcasses under the conditions examined. The combination of time and high temperature of the compost cycle effectively degraded viral RNA in cell culture media that should provide optimum stability. Complex compost material matrices collected from windrow sections yielded undetectable PEDV RNA by qRT-PCR after one 36-day compost cycle despite incomplete decomposition of soft tissue. Sarah Vitosh-Sillman, John Dustin Loy, Bruce Brodersen, Clayton Kelling, Kent Eskridge and Amy Millmier Schmidt; Effectiveness of Composting as a Biosecure Disposal Method for Porcine Epidemic Diarrhea Virus (PEDV)-Infected Pig Carcasses; Porcine Health Management20173:22 https://doi.org/10.1186/s40813-017-0068-z