Detection and disease diagnosis trends (2017–2022) for Streptococcus suis, Glaesserella parasuis, Mycoplasma hyorhinis, Actinobacillus suis and Mycoplasma hyosynoviae at Iowa State University Veterinary Diagnostic Laboratory
Authors: Silva Ana Paula Serafini Poeta , Almeida Marcelo , Michael Alyona , Rahe Michael C. , Siepker Christopher , Magstadt Drew R. , Piñeyro Pablo , Arruda Bailey L. , Macedo Nubia R. , Sahin Orhan , Gauger Philip C. , Krueger Karen M. , Mugabi Robert , Streauslin Jessica S. , Trevisan Giovani , Linhares Daniel C. L. , Silva Gustavo S. , Fano Eduardo , Main Rodger G. , Schwartz Kent J. , Burrough Eric R. , Derscheid Rachel J. , Sitthicharoenchai Panchan , Clavijo Maria J. 
Published: December 2023

Background

Accurate measurement of disease associated with endemic bacterial agents in pig populations is challenging due to their commensal ecology, the lack of disease-specific antemortem diagnostic tests, and the polymicrobial nature of swine diagnostic cases. The main objective of this retrospective study was to estimate temporal patterns of agent detection and disease diagnosis for five endemic bacteria that can cause systemic disease in porcine tissue specimens submitted to the Iowa State University Veterinary Diagnostic Laboratory (ISU VDL) from 2017 to 2022. The study also explored the diagnostic value of specific tissue specimens for disease diagnosis, estimated the frequency of polymicrobial diagnosis, and evaluated the association between phase of pig production and disease diagnosis.

Results

S. suisandG. parasuisbronchopneumonia increased on average 6 and 4.3%,whileS. suisendocarditis increased by 23% per year, respectively.M. hyorhinisandA. suisassociated serositis increased yearly by 4.2 and 12.8%, respectively. A significant upward trend inM. hyorhinisarthritis cases was also observed. In contrast,M. hyosynoviaearthritis cases decreased by 33% average/year. Investigation into the diagnostic value of tissues showed that lungs were the most frequently submitted sample, However, the use of lung for systemic disease diagnosis requires caution due to the commensal nature of these agents in the respiratory system, compared to systemic sites that diagnosticians typically target. This study also explored associations between phase of production and specific diseases caused by each agent, showcasing the role ofS. suisarthritis in suckling pigs, meningitis in early nursery and endocarditis in growing pigs, and the role ofG. parasuis, A. suis, M. hyorhinisandM. hyosynoviaedisease mainly in post-weaning phases. Finally, this study highlighted the high frequency of co-detection and -disease diagnosis with other infectious etiologies, such as PRRSV and IAV, demonstrating that to minimize the health impact of these endemic bacterial agents it is imperative to establish effective viral control programs.

Conclusions

Results from this retrospective study demonstrated significant increases in disease diagnosis forS. suis,G. parasuis,M. hyorhinis,andA. suis, and a significant decrease in detection and disease diagnosis ofM. hyosynoviae. High frequencies of interactions between these endemic agents and with viral pathogens was also demonstrated. Consequently, improved control programs are needed to mitigate the adverse effect of these endemic bacterial agents on swine health and wellbeing. This includes improving diagnostic procedures, developing more effective vaccine products, fine-tuning antimicrobial approaches, and managing viral co-infections.