MG is a chronic disease for life. It stays in the flock until the last bird is alive. Symptoms come and go. It is incurable, although the treatment can help with symptoms.
https://extension.umd.edu/sites/extension.umd.edu/files/2022-04/FS-1008 Recognizing and Preventing Mycoplasma gallisepticum (MG) Infecti....pdf
https://www.freedomrangerhatchery.com/blog/protecting-your-flock-what-you-need-to-know-about-mg-ms/
https://extension.umd.edu/sites/extension.umd.edu/files/2022-04/FS-1008 Recognizing and Preventing Mycoplasma gallisepticum (MG) Infecti....pdf
https://www.freedomrangerhatchery.com/blog/protecting-your-flock-what-you-need-to-know-about-mg-ms/