Asymptomatic tuberculosis among household contacts of active pulmonary tuberculosis cases: a systematic review and meta-analysis.
Ayinalem Alemu, Getachew Seid, Adamu Tayachew et al.
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In 30 seconds
This systematic review and meta-analysis estimated the prevalence of asymptomatic tuberculosis (TB) among household contacts of people with active pulmonary TB. Eighteen studies from 12 countries, including 46,480 contacts, were included. The pooled prevalence of TB among asymptomatic contacts was 4.0% (95%CI: 2.1-5.8%), and asymptomatic disease represented 51.0% (95%CI: 39.7-62.2%) of all identified TB cases. The authors conclude that screening based on symptoms alone may miss a substantial share of TB among household contacts.
Key findings
- Pooled TB prevalence among asymptomatic household contacts was 4.0% (95%CI: 2.1-5.8%).
- Asymptomatic TB accounted for 51.0% (95%CI: 39.7-62.2%) of identified TB cases among household contacts.
- An estimated 2% (95%CI: 0.7-3.2%; I²: 90.67%) of asymptomatic contacts without TB at baseline developed TB during follow-up.
- Male sex, a chest X-ray suggestive of TB, cigarette smoking, and drug use were associated with asymptomatic TB.
Why it matters
A substantial proportion of TB identified among household contacts was asymptomatic, indicating that symptom-based assessment alone may not detect all cases. Recognising this burden is relevant to early case detection and efforts to reduce transmission, while the pooled estimates also show that asymptomatic disease occurs across the included settings.
What to keep in mind
The pooled estimates combine studies from different countries, and follow-up TB estimates showed high heterogeneity (I²: 90.67%).