Background: There are large knowledge gaps on the transmission dynamics of Mycobacterium tuberculosis in settings where both tuberculosis and human immunodeficiency virus (HIV) are endemic. We aimed to assess the infectiousness of tuberculosis patients coinfected with HIV.
Methods: We systematically searched for studies of contacts of both HIV-positive and HIV-negative tuberculosis index cases. Our primary outcome was Mycobacterium tuberculosis infection in contacts. Data on sputum smear and lung cavitation status of index cases were extracted from each study to assess effect modification. Secondary outcomes included prevalent tuberculosis and HIV in contacts of HIV-positive and HIV-negative index cases.
Results: Of 5255 original citations identified, 32 studies met inclusion criteria, including 25 studies investigating M. tuberculosis infection (Nparticipants = 36 893), 13 on tuberculosis (Nparticipants = 18 853), and 12 on HIV positivity (Nparticipants = 18 424). Risk of M. tuberculosis infection was lower in contacts of HIV-positive index cases (odds ratio [OR], 0.67, 95% confidence interval [CI], .58-.77) but was heterogeneous (I2 = 75.1%). Two factors modified this relationship: the lung cavitary status of the index case and immunosuppression (measured through CD4 counts or HIV or acquired immunodeficiency syndrome diagnoses) among index people living with HIV. Rates of HIV were consistently higher in contacts of coinfected index cases (OR, 4.9; 95% CI, 3.0-8.0). This was modified by whether the study was in sub-Saharan Africa (OR, 2.8; 95% CI, 1.6-4.9) or in another global region (OR, 9.8; 95% CI, 5.9-16.3).
Conclusions: Tuberculosis patients coinfected with HIV are less infectious than HIV-uninfected cases when they have severe immunosuppression or paucibacillary disease. Contacts of coinfected index cases are almost 5 times more likely to also have HIV.
Keywords: human immunodeficiency virus; infectiousness; transmission dynamics; tuberculosis.
© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.