Yield of contact tracing from pediatric tuberculosis index cases in Gaborone, Botswana
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SETTING: Contact tracing using pediatric index cases has not been adequately investigated in high tuberculosis (TB) and human immunodeficiency virus (HIV) prevalence settings. OBJECTIVE: To determine the yield of contact tracing in household contacts of pediatric TB index cases in Botswana. DESIGN: Index cases included all pediatric (age ≤ 13 years) TB admissions from January 2009 to December 2011 to Botswana's largest referral hospital. A contact tracing team identified cases, conducted home visits, symptom-screened contacts and referred those with ≥ 1 TB symptoms. The primary outcome was newly diagnosed TB in a contact. RESULTS: From 163 pediatric index cases, 548 contacts were screened (median 3 contacts/case, interquartile range [IQR] 2-4). Of these, 49 (9%) were referred for positive symptoms on screening and 27/49 (55%) were evaluated for active TB. Twelve new TB cases were diagnosed (12/548, 2.2%); the median age was 31 years (IQR 23-38); 11 (92%) were smear-positive. Ten (83%) had known HIV status: 7 (70%) were HIV-positive. To find one new TB case, the number needed to contact trace (index cases/new cases) was 13.6, and the number needed to screen (contacts/new cases) was 46. CONCLUSION: This yield of contact tracing using pediatric index cases is similar to the traditional adult index case approach. Improving the proportion of symptomatic contacts evaluated may increase yield.
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