Incident Mycobacterium tuberculosis infection in household contacts of infectious tuberculosis patients in Brazil
نویسندگان
چکیده
BACKGROUND In household contact investigations of tuberculosis (TB), a second tuberculin skin test (TST) obtained several weeks after a first negative result consistently identifies individuals that undergo TST conversion. It remains unclear whether this delay in M. tuberculosis infection is related to differences in the infectious exposure, TST boosting, partial host resistance, or some other factor. METHODS We conducted a household contact study Vitória, Brazil. Between 2008 and 2013, we identified culture-positive pulmonary TB patients and evaluated their household contacts with both a TST and interferon gamma release assay (IGRA), and identified TST converters at 8-12 weeks post study enrollment. Contacts were classified as TST-positive (≥10 mm) at baseline, TST converters, or persistently TST-negative. We compared TST converters to TST-positive and to TST-negative contacts separately, using generalized estimating equations. RESULTS We enrolled 160 index patients and 838 contacts; 523 (62.4%) were TST+, 62 (7.4%) TST converters, and 253 (30.2%) TST-. TST converters were frequently IGRA- at 8-12 weeks. In adjusted analyses, characteristics distinguishing TST converters from TST+ contacts (no contact with another TB patient and residence ownership) were different than those differentiating them from TST- contacts (stronger cough in index patient and contact BCG scar). CONCLUSIONS The individual risk and timing of M. tuberculosis infection within households is variable and dependent on index patient, contact and environmental factors within the household, and the surrounding community. Our findings suggest a threshold effect in the risk of infection in humans.
منابع مشابه
Author’s response to reviews Title: Incident Mycobacterium tuberculosis Infection in Household Contacts of Infectious Tuberculosis patients in Brazil Authors:
متن کامل
The Prevalence of Latent Tuberculosis Infection and Smear Positive Pulmonary Tuberculosis in People with Household Close Contact with Tuberculosis in North of Iran
One of the recommended strategies for preventing tuberculosis is to screen high-risk populations with respect to Mycobacterium tuberculosis (TB) infection. The aim of the present study was to investigate latent infection and active tuberculosis in people with close household contact. It was a cross-sectional descriptive, analytical study with the sample size of 668 people from homes with one in...
متن کاملRisk of tuberculosis among household contacts in Salvador, Bahia.
UNLABELLED Tuberculosis is one of the most important infectious diseases in the world. Only 68% of the estimated new tuberculosis (TB) cases in Brazil are diagnosed. Our aim was to determine the risk of infection among household contacts. STUDY DESIGN Cohort of tuberculin-negative household contacts followed for 12 months. METHODS Household contacts of randomly selected index acid-fast baci...
متن کاملMycobacterium tuberculosis Dominance over Nontuberculous Mycobacteria Irrespective of Immune Status: An Indian Scenario
Introduction: In HIV-associated tuberculosis cases, identifying nontuberculous Mycobacteria (NTM) from clinical samples has become essential regarding patients’ treatment and prognosis. This study aims to determine the prevalence of different Mycobacteria species from immunocompromised and immunocompetent patients with suspected tuberculosis attending a tertiary care hospital in Kolkata, India....
متن کاملTuberculosis contacts but not patients have higher gamma interferon responses to ESAT-6 than do community controls in The Gambia.
The Mycobacterium tuberculosis antigen ESAT-6 has been proposed for tuberculosis immunodiagnosis. In The Gambia, 30% of community controls produced gamma interferon (IFN-gamma) in response to ESAT-6. Increased proportions of responders and intensities of responses were found in household contacts. Responses that were initially low in tuberculosis patients increased after treatment. An ESAT-6 IF...
متن کامل