Is all tuberculosis contagious? Of course not, the contagiousness of tuberculosis comes from what state; there are two conditions: first, after infection with Mycobacterium tuberculosis is in the active stage, that is, the person himself has symptoms. Second, in the state of sputum and bacillus excretion, that is, what the person has: 1, such as fever, wasting, persistent cough, which is a subjective symptom; 2, the actual examination, found cough, sputum with Mycobacterium tuberculosis, which is called bacillus excretion, positive bacillus excretion is truly infectious. And if it is only tuberculous pleurisy or secondary bone tuberculosis, the others are not contagious, and those who have had tuberculosis are called old tuberculosis, not in the active stage and not contagious, so the contagiousness of tuberculosis is not as harmful as imagined, and should be understood rationally. If you have relatives or friends around you who are considering tuberculosis, you should always recommend going to the CDC or a specialized respiratory medicine department for professional screening to see if the bacteria are draining in order to identify whether it is contagious and protective for everyone.