Duration of Mycoplasma hyopneumoniae detection in pigs following purposeful aerosol exposure

• Published in: Veterinary microbiology Vol. 282; p. 109758
• Main Authors: McDowell, Emily, Pieters, Maria, Spronk, Taylor, Nerem, Joel, Fano, Eduardo, Dee, Scott, Sponheim, Amanda
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.07.2023
• Subjects: Aerosol exposure; Aerosols - therapeutic use; Animals; Duration of infection; Elimination; Farms; Female; Gilt acclimation; Lung - microbiology; Mycoplasma hyopneumoniae; Mycoplasma hyopneumoniae - isolation & purification; Persistence; Pneumonia of Swine, Mycoplasmal - microbiology; Pneumonia of Swine, Mycoplasmal - prevention & control; Sus scrofa; Persistence; Aerosol exposure; Mycoplasma hyopneumoniae; Duration of infection; Gilt acclimation; Elimination
• ISSN: 0378-1135; 1873-2542
• DOI: 10.1016/j.vetmic.2023.109758

Swine disease elimination programs for Mycoplasma hyopneumoniae are commonly applied in the North American swine industry and may include the aerosolization of medium containing lung tissue to achieve population exposure prior to start. Field data has indicated M. hyopneumoniae PCR detection in pigs beyond 240 days post-herd closure (dphc; planned end of an elimination program) and is thought to contribute to disease elimination programs’ failure. Here, the duration of M. hyopneumoniae detection in sows and replacement gilts following aerosolized lung homogenate exposure, as part of a dual disease elimination program, was determined. A subset of sows and gilts from a commercial sow herd and off-site gilt development unit were longitudinally sampled to collect deep tracheal catheter secretions at various times post-exposure. Samples were tested for M. hyopneumoniae using a species-specific real-time PCR. A proportion of 58, 51, 52, 19, and 2% females were detected positive at 30, 60, 120, 180 and 240 dphc, respectively. Noteworthy, a greater proportion of gilts exposed at the off-site GDU were detected PCR positive for M. hyopneumoniae at each sampling event, compared to sows. In this study, assaying for genetic material in live female pigs showed extended detection of M. hyopneumoniae until at least 240 dphc. This data suggests persistence of M. hyopneumoniae longer than previously reported and highlights the importance of performing diagnostic testing to confirm negativity to the bacterium, prior to opening sow herds, especially late in the herd closure timeline. •Duration of M. hyopneumoniae detection after aerosol exposure was at least 240 days.•A decrease in the proportion of PCR positive sows and gilts was observed over time.•A greater proportion of gilts were M. hyopneumoniae PCR positive compared to sows.•PCR testing was critical for the detection of M. hyopneumoniae beyond 8 months.