ppd refers to tuberculin test, ppd strong positive indicates that the patient may be infected with tuberculosis bacillus or vaccinated with BCG vaccine, usually lasts for several years or decades before transforming, and some may even last for life. Strongly positive ppd is the body’s allergic reaction to tuberculosis bacillus, suggesting that the patient may be infected with tuberculosis bacillus. ppd strong positive will last for how many years to change according to the virulence of the bacteria and the body’s immune status of the integrated consideration, may last for several years or decades, and some patients may be ppd strong positive for life. Some patients may remain ppd-positive for life. Strong ppd-positivity can also be seen in people who have had a strong allergic reaction to BCG vaccination, which usually lasts for life and does not require special treatment. If you have ppd strong positive, you need to go to the hospital in time, through the chest X-ray, CT and other tests to determine whether you have tuberculosis, and if you have the disease, you need to take the medication according to the doctor’s guidance and regular checkups.