Risk of infection with Mycobacterium tuberculosis among children and mothers in Somalia

The prevalence of infection with Mycobacterium tuberculosis in prewar Somalia was surveyed by testing the tuberculin sensitivity of 2,792 infants and children and 446 mothers in two towns: Burao in the dry north and Kismayo in the humid south. Sensitivity increased with age, but considerable differences prevailed between the towns. In Burao a roughly linear increase in sensitivity was found, with no sensitivity in infancy, sensitivity in 19% of children at 7 years, and sensitivity in 54% of children at 15 years; in Kismayo the corresponding figures were 9%, 28%, and 47%, respectively. Together, the correlation of prior BCG vaccination with a positive tuberculin test in Burao and the lack of these findings in Kismayo suggested that vaccination had partly failed in Kismayo, where living conditions also favored the transmission of M. tuberculosis. The annual risk of M. tuberculosis infection was approximately 1% higher in the south than in the north and was much higher during the first 3 years of life than later. This study--the first defining the risk of M. tuberculosis infection among children of various ages in Somalia--indicates that this risk is greatest in the southern parts of the country and among infants and young children.