Age-specific prevalence of TB infection among household contacts of pulmonary TB: Is it time for TB preventive therapy?
BACKGROUND
Household 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.


METHODS
A 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.


RESULTS
Of 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).


CONCLUSION
This 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.
['Dolla|Chandra Kumar|CK|', 'Padmapriyadarsini|Chandrasekaran|C|', 'Thiruvengadam|Kannan|K|', 'Lokhande|Rahul|R|', 'Kinikar|Aarti|A|', 'Paradkar|Mandar|M|', 'Bm|Shrinivas|S|', 'Murali|Lakshmi|L|', 'Gupte|Akshay|A|', 'Gaikwad|Sanjay|S|', 'Selvaraju|Sriram|S|', 'Padmanaban|Yashoda|Y|', 'Pattabiraman|Sathyamurthy|S|', 'Pradhan|Neeta|N|', 'Kulkarni|Vandana|V|', 'Shivakumar|Shri Vijay Bala Yogendra|SVBY|', 'Prithivi|Munivardhan|M|', 'Kagal|Anju|A|', 'Karthavarayan|Barath Thopili|BT|', 'Suryavanshi|Nishi|N|', 'Gupte|Nikhil|N|', 'Kumaran|Paul|P|', 'Mave|Vidya|V|', 'Gupta|Amita|A|']
D000293:Adolescent D000328:Adult D000367:Age Factors D002648:Child D002675:Child, Preschool D003430:Cross-Sectional Studies D005191:Family Characteristics D005260:Female D006801:Humans D007194:India D055985:Latent Tuberculosis D008297:Male D008875:Middle Aged D015995:Prevalence D011446:Prospective Studies D012307:Risk Factors D014374:Tuberculin Test D014397:Tuberculosis, Pulmonary D055815:Young Adult
latent TB force of infection transmission close contacts