WHO report (2017) : The estimated incidence of TB in India in 2015 was around 2.8 million (27% of global incidence). Of these, 0.26 million (8.9%) are pediatric cases. General : Most people infected with the bacillus never develop an active tuberculous disease. About 5% to 10% of people with latent TB go on to develop active tuberculosis within 2 to 3 months to years after infection. Why? How?
In a case I know, a mother and son exposed via skin to infected sputum in 1974, together developed PTB in 1980. Here route of entry, infectious dose and immunity status played a role. Exposure : Tuberculosis is infectious when it is in the lungs or larynx. 1.) Droplet Infection: The respirable droplet nuclei are 1–5 microns in diameter in which 1-2 bacilli remain suspended in the air for many hours. People get infected by inhaling the bacillus. 2.) Sputum: Exogenous infection results from direct…
