Cough relative to the detection of Mycoplasma hyopneumoniae DNA in environmental and clinical specimens

Authors: POETA SILVA, ANA PAULA - Iowa State University; STORINO, GABRIEL - Sao Paulo State University (UNESP); MATIAS FERREYRA, FRANCO - Iowa State University; ZHANG, MIN - Iowa State University; FANO, EDUARDO - Boehringer Ingelheim; POLSON, DALE - Boehringer Ingelheim; WANG, CHONG - Iowa State University; DERSCHEID, RACHEL - Iowa State University; ZIMMERMAN, JEFFREY - Iowa State University; CLAVIJO, MARIA - Iowa State University; Arruda, Bailey

Submitted to: BMC Porcine Health Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2021
Publication Date: 1/25/2022
Citation: Poeta Silva, A., Storino, G., Matias Ferreyra, F., Zhang, M., Fano, E., Polson, D., Wang, C., Derscheid, R., Arruda, B.L., Zimmerman, J., Clavijo, M. 2022. Cough relative to the detection of Mycoplasma hyopneumoniae DNA in environmental and clinical specimens. BMC Porcine Health Management. (2022)8:6. https://doi.org/10.1186/s40813-022-00249-y.
DOI: https://doi.org/10.1186/s40813-022-00249-y

Interpretive Summary: Mycoplasma hyopneumoniae is an important cause of respiratory disease in swine. The association of cough with Mycoplasma hyopneumoniae (MHP) DNA detection in specimens was evaluated under conditions in which the MHP status of inoculated and contact-infected pen mates was closely monitored. Specimens included tracheal swabs, oral fluids, drinker wipes and air samples. Tracheal swabs provided the earliest detection; however, oral fluids and drinker wipes provided an easier alternative for MHP DNA detection at the pen level when cough was present and prevalence was high.

Technical Abstract: The association of cough with Mycoplasma hyopneumoniae (MHP) DNA detection in specimens was evaluated under conditions in which the MHP status of inoculated and contact-infected pen mates was closely monitored for 59 days post-inoculation (DPI). Seven-week-old pigs (n = 39) were allocated to five rooms (with one pen). Rooms contained 9 pigs each, with 1, 3, 6, or 9 MHP-inoculated pigs, respectively, except Room 5 (three sham-inoculated pigs). Cough data (2x week) and specimens (tracheal swabs (2x week), oral fluids (daily), drinker wipes (~1x week), and air samples (3x week )) were collected. At 59 DPI, pigs were euthanized, and lung and trachea were evaluated for gross and microscopic lesions. MHP DNA was first detected in tracheal swabs from inoculated pigs (DPI 3), then oral fluids (DPI 8), air samples (DPI 10), and drinker wipes (21 DPI). MHP DNA was detected in oral fluids in 17 of 59 (Room 1) to 43 of 59 (Room 3) samples, drinker wipes in 4 of 8 (Rooms 2 and 3) to 5 of 8 (Rooms 1 and 4) samples, and air samples in 5 (Room 2) or 3 (Room 4) of 26 samples. Regression analyses showed that cough incidence rates were associated with MHP DNA detection in oral fluids (P<0.01) and nearly associated with drinker wipes (P=0.08). Cough pattern over the course of MHP infection included an initiation period, with a lower cough incidence rate in the first 15 DPIs, a peak period (DPIs 15 to 29), and then a resolution period at DPIs >45. Pathology data revealed an association between the period when infection was first detected and the severity of gross lung lesions. Regardless of the period of infection, cilia were shorter in MHP-infected pigs versus negative controls (P<0.05). A diagnosis of MHP can be confounded by its long incubation period and slow transmission rate. Dry, non-productive coughs suggest the presence of MHP, but laboratory testing and MHP DNA detection is required for confirmation. Although tracheal swabs provided the earliest detection, oral fluids and drinker wipes provided an easier alternative for MHP DNA detection at the pen level when cough was present.