Age-related tuberculosis incidence and severity in children under 5 years of age in Cape Town, South Africa

SETTING: Limited data are available on the characteristics of tuberculosis (TB) disease in young children, especially in high-burden countries. OBJECTIVE: To assess the incidence and severity of TB in children aged < 5 years. METHODS: TB records and chest radiographs of children born in Cape Town in 1999 and diagnosed with TB between 1.999 and 2004 were reviewed retrospectively. RESULTS: A total of 1607 cases were registered. The cumulative incidence of definite (bacteriologically confirmed) and probable (radiological evidence and >= 1 TB clinical feature) TB in children aged < 5 years was 2.9% and was highest between the ages of 12 and 23 months. Of 1233 children with definite or probable TB, 506 (41%) had severe disease (dissemination, cavities or > 1 lobe involved). The under 5 years incidence of disseminated TB was 0.33%. Of 239 (15%) cases that were bacteriologically confirmed, clinical features typical of TB disease were individually present In < 60%. The most common combined symptoms were cough for > 2 weeks and weight loss, occurring in 43/239 (18%). CONCLUSION: TB incidence was high, and peaked in children aged 1.2-23 months. Many children experienced severe disease. A fifth of children with microbiologically confirmed disease presented with only one feature typically associated with TB.