The Swine Health Information Center recently renewed funding for the Domestic Swine Disease Monitoring Reports through September 2025. Drs. Giovani Trevisan and Daniel Linhares, Iowa State University, lead the program which was initially funded by SHIC in 2017 and continues to focus on the analysis and reporting of collated veterinary diagnostic laboratory data to identify emerging endemic disease trends. Monthly reports provide an early warning system for veterinarians and producers to prompt preventative actions such as increasing monitoring and heightening biosecurity measures. Highlighted from 2024, new analysis tools and additional pathogen data helped enhance the value of the reports to the US swine industry.
Access SHIC’s Domestic Swine Disease Monitoring Reports here.
The SDRS is the only publicly available source of swine health information from 6 US veterinary diagnostic laboratories representing >96% of all swine samples submitted for testing in the National Animal Health Laboratory Network. With a database containing information for nine endemic porcine pathogens and more than 1.5 million cases, SDRS is one of the largest US and international databases for veterinary diagnostic information. The SDRS has provided science-based spatiotemporal information on pathogen activity in all age categories, from boar studs to breeding herds to finishing with great representation of the US swine industry.
Incorporated in 2024, an SDRS Blast tool for PRRSV allows veterinarians, producers, and other users to compare their ORF5 sequences with those in the SDRS database, identify when and where similar sequences in the database have occurred before, and define their genetic nomenclatures by lineage, RFLP, and variant. Further, new SDRS dashboards with revamped information debuted in 2024, improving navigation and providing new tools such as the influenza A virus state-level monitoring. Weekly monitoring of influenza A virus (IAV) PCR detection was added in the PDF reports.
Also added in 2024 is a new PRRSV ORF 5 sequence page in the PDF report. This page includes charts with information about the total number of PRRSV ORF5 sequences performed, the total number of sequences with less than 95% similarity within the SDRS database, the top Lineage and RFLP detected in the US, and the most frequent sequences detected across US states. Implementation of the PRRSV ORF5 variant classification system and display in the SDRS Blast tool also occurred.
PEDV genotype data was included in 2024 to provide new information on variant data that can be classified based on specific genetic characteristics of the spike protein as INDEL and Non-INDEL variants. Moreover, SDRS is one of the sources of information supporting the AASV PEDV Elimination Task Force established in 2024, providing data to aid the US swine industry in tracking PEDV activity in the field.
In 2024, SDRS project website pages including the dashboards and Blast tool had 2,215 unique IP visitors. Across the calendar year, 12 editions of PDF, audio, and video reports were shared via email to 474 registered receivers from 195 organizations from 15 different countries. On the FieldEpi LinkedIn page, the SDRS videos achieved more than 51,395 visualizations. SDRS hosted 12 podcast editions with 11 special guests. The SDRS YouTube channel achieved 5,162 views of video reports and education material. Audio reports were shared through podcast platforms, achieving 3,206 downloads from 23 different countries.
SDRS has shown its utility as a monitoring and early warning system that can identify and track significant and unexpected changes occurring for swine pathogens. During fall 2024, PRRSV had the highest historical percentage of PCR-positive submissions in the wean-to-market category (42.3% of positive cases) since fall 2020. The wean-to-market category represented 56% of the L1C.5 detections, with much of this activity being related to a record detection of PRRSV lineage 1C.5 within a single month (501 in November 2024).
The most frequent wild-type PRRSV-2 strains detected in 2024 were L1C.5 (L1C variant) 1-4-4, L1A 1-7-4, and L1C.2 1-2-4. Of all wild-type strains detected in 2024, over 50% (3,144) were L1C.5, breaking the record of detection within a year since its first emergence in 2020. Most of the sequences were detected in Iowa (1,873), followed by Minnesota (524), Missouri (309), Nebraska (160), and Ohio (40).
During summer 2024, PEDV had the lowest historical percentage of positive submissions in the adult/sow farm category (4.42% of positive cases). March 22, 2021, marked the last field sample received at an SDRS laboratory with a PCR positive result for TGEV. Up to December 2024, more than 165,000 submissions, including more than 400,000 samples, have been tested for TGEV with no TGEV-positive result being detected.
M. hyopneumoniae percentage of PCR-positive submissions from breeding herds have decreased substantially from 2021 (21.75%) to 2022 (13.5%) and continued to decrease in 2024 (12%). In contrast, in the wean-to-market category, M. hyopneumoniae positivity reached the highest levels (27%) since the fall of 2020. However, using ISU VDL data, the number of cases with a confirmed tissue diagnosis indicating lesions for M. hyopneumoniae decreased over time, reaching a record low number in 2024 (203 cases).
In 2024, PCV3 maintained its detection trend as being the only pathogen with higher positivity in adult/sow farms compared to the wean-to-market category across all months. Yearly average PCV2 positivity in the adult/sow farm category decreased from 39% in 2023 to 33% in 2024. Also, PCV2-confirmed tissue diagnosis decreased in 2024 (399 cases) compared with 2023 (540).
Influenza A virus bi-seasonality pattern of PCR detection continued to occur in the spring and fall of 2024 as expected. However, the peaks of overall positivity were slightly higher in 2024 compared with 2023. In 2023, the peaks of overall IAV positivity occurred in May (34% positivity) and November (33% positivity). In 2024, the peaks of positivity occurred in March (38%) and November (35%).
In 2024, there were fewer influenza A virus subtyping and PEDV genotype tests. The majority of this decrease was attributed to testing strategies by some participant VDLs that started to offer the screening PCR separate from the subtype/genotype PCRs that were previously offered together. Also, some production systems started to test PEDV genotype in-house.
At the ISU VDL, PRRSV had the highest number of confirmed diagnoses (2,566) followed by Streptococcus suis (1,735) and influenza A virus (935) in 2024. Pathogens including PRRSV, influenza A virus, P. multocida, Actinobacillus suis, Streptococcus suis, and Salmonella have given increased signals for diagnosis in October and November 2024.
The information gathered and reported for the SDRS project serves as a vital resource for producers and veterinarians to monitor and identify changes in swine health. Early identification of diagnostic trends in targeted pathogens can support actions geared towards disease prevention such as increased monitoring and increased focus on biosecurity and supports SHIC’s mission to reduce the threat and impact of emerging diseases.
The Swine Health Information Center, launched in 2015 with Pork Checkoff funding, protects and enhances the health of the US swine herd by minimizing the impact of emerging disease threats through preparedness, coordinated communications, global disease monitoring, analysis of swine health data, and targeted research investments. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. For more information, visit http://www.swinehealth.org or contact Dr. Megan Niederwerder at mniederwerder@swinehealth.org or Dr. Lisa Becton at lbecton@swinehealth.org.