Hi & Welcome to HCM. I appreciate your concern for the possibility of spread of TB infection in the close contacts at home. Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs. TB is spread through the air from one person to another. The TB bacteria are put into the air when a person with TB disease of the lungs or throat coughs, sneezes, or speaks. TB bacteria get into the air and can remain there for SEVERAL HOURS. People at highest risk of becoming infected are close contacts - those individuals who have prolonged, frequent, or intense contact with a person with infectious tuberculosis. They may breathe in these bacteria and become infected. The most important way to stop the spread of tuberculosis is for patients who have active TB to cover their mouth and nose when coughing, and to take all the TB medicine exactly as ordered by the doctor. Beside all the close contacts should be given the anti TB drug Isoniazide once daily for at least 6 months to prevent the disease. Hope this could answer your query.