A pre-tested questionnaire was used by a trained counselor to obtain information on demographic characteristics, social and medical history from the subjects. Other important information about PTB such as previous BCG vaccination, contact with an index case and exposure to tuberculin skin test were also obtained. Laboratory investigations: Three early morning sputum were collected from each consenting asymptomatic subject. The samples were transported to TB laboratory of the department of Medical Microbiology and Parasitology, UCH, for immediate processing. Each sample was smeared, air-dried, fixed and stained with Z-N reagents. The staining procedure was controlled by using known AFB slide and slide stained with egg albumin as positive and negative controls respectively
