The successful candidate will develop and analyse a mathematical model of contact patterns and Mycobacterium tuberculosis transmission in adults and children. Force of infection (FOI) in children is (relatively) easy to measure, and so is often used as a proxy for overall disease incidence. The relationship between the two variables is not clear however, and will vary with contact patterns between adults and children, and the amount of disease that is due to reactivation. The successful candidate will examine the relationship between FOI in children and the incidence of TB disease in the general population. This will lead to a better understanding of the relationship between the two variables, and under what circumstances FOI in children should and should not be used as a proxy for disease incidence. This work will feed into ongoing discussions about the utility of latent LTBI surveys with WHO.