• Chandra Kumar Dolla, Chandrasekaran Padmapriyadarsini, Kannan Thiruvengadam, Rahul Lokhande, Aarti Kinikar, Mandar Paradkar, Shrinivas Bm, Lakshmi Murali, Akshay Gupte, Sanjay Gaikwad, Sriram Selvaraju, Yashoda Padmanaban, Sathyamurthy Pattabiraman, Neeta Pradhan, Vandana Kulkarni, Shri Vijay Bala Yogendra Shivakumar, Munivardhan Prithivi, Anju Kagal, Barath Thopili Karthavarayan, Nishi Suryavanshi, Nikhil Gupte, Paul Kumaran, Vidya Mave, and Amita Gupta.
• Epidemiology, National Institute for Research in Tuberculosis, 1, Mayor Sathyamoorthy Road, Chetpet, Chennai, Tamil Nadu, India.
• Trans. R. Soc. Trop. Med. Hyg. 2019 Oct 11; 113 (10): 632-640.

BackgroundHousehold contacts (HHCs) of TB patients are at high risk of developing evidence of latent TB infection (LTBI) and active disease from the index patient. We estimated the age-specific prevalence of LTBI and the force of infection (FI), as a measure of recent transmission, among HHCs of active TB patients.MethodsA cross-sectional analysis of HHCs of pulmonary TB patients enrolled in a prospective study, 'CTRIUMPh', was conducted at two sites in India. LTBI was defined as either a positive tuberculin skin test (induration ≥5 mm) or QuantiFERON-Gold in tube test (value ≥0.35 IU/ml) and was stratified by age. FI, which is a measure of recent transmission of infection and calculated using changes in age-specific prevalence rates at specific ages, was calculated. Factors associated with LTBI were determined by logistic regression models.ResultsOf 1020 HHCs of 441 adult pulmonary TB cases, there were 566 (55%) females and 289 (28%) children aged ≤15 y. While screening for the study 3% of HHC were diagnosed with active TB. LTBI prevalence among HHCs of pulmonary TB was 47% at <6 y, 53% between 6-14 y and 78% between 15-45 y. FI increased significantly with age, from 0.4 to 1.15 in the HHCs cohort (p=0.05).ConclusionThis study observed an increased prevalence of LTBI and FI among older children and young adults recently exposed to infectious TB in the household. In addition to awareness of coughing etiquette and general hygiene, expanding access to TB preventive therapy to all HHCs, including older children, may be beneficial to achieve TB elimination by 2035.© The Author(s) 2019. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

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