Does antiretroviral treatment increase the infectiousness of smear-positive pulmonary tuberculosis?

Abstract

BACKGROUND: Understanding of the effects of human immunodeficiency virus (HIV) infection and antiretroviral treatment (ART) on Mycobacterium tuberculosis transmission dynamics remains limited. We undertook a cross-sectional study among household contacts of smear-positive pulmonary tuberculosis (TB) cases to assess the effect of established ART on the infectiousness of TB. METHOD: Prevalence of tuberculin skin test (TST) positivity was compared between contacts of index cases aged 2–10 years who were HIV-negative, HIV-positive but not on ART, on ART for <1 year and on ART for ⩾1 year. Random-effects logistic regression was used to take into account clustering within households. RESULTS: Prevalence of M. tuberculosis infection in contacts of HIV-negative patients, HIV-positive patients on ART ⩾1 year and HIV-positive patients not on ART/on ART <1 year index cases was respectively 44%, 21% and 22%. Compared to contacts of HIV-positive index cases not on ARTor recently started on ART, the odds of TST positivity was similar in contacts of HIV-positive index cases on ART ⩾1 year (adjusted OR [aOR] 1.0, 95%CI 0.3–3.7). The odds were 2.9 times higher in child contacts of HIV-negative index cases (aOR 2.9, 95%CI 1.0–8.2). CONCLUSIONS: We found no evidence that established ART increased the infectiousness of smear-positive, HIV-positive index cases.

Transmission of drug-resistant tuberculosis in HIV-endemic settings

“…This increase in the number of infected contacts of drug-resistant index cases could be due to prolonged duration of infectiousness in drug-resistant tuberculosis as a result of diagnostic delays. 26 Immunosuppressed HIV-positive index cases with drug-susceptible tuberculosis are less likely to transmit to household contacts than HIV-negative cases, 27–31 probably due to aforementioned differences in cavitation and bacillary load. 27,29–31 Contact investigation in rural South Africa 32 has also shown the force of infection in an HIV-endemic setting.…”

“…26 Immunosuppressed HIV-positive index cases with drug-susceptible tuberculosis are less likely to transmit to household contacts than HIV-negative cases, 27–31 probably due to aforementioned differences in cavitation and bacillary load. 27,29–31 Contact investigation in rural South Africa 32 has also shown the force of infection in an HIV-endemic setting. It was found that, of 793 contacts of multidrug-resistant tuberculosis index cases, 14 (1.8%) were diagnosed with multidrug-resistant tuberculosis (incidence 1765 of 100 000) and 19 (2.0%) of 973 extensively drug-resistant tuberculosis contacts had extensively drug-resistant tuberculosis (incidence 1952 of 100 000) within a median of 70 days (IQR 57–89) of index case diagnosis.…”

Prevalence and risk factors for latent tuberculosis infection among household contacts of index cases in two South African provinces: Analysis of baseline data from a cluster-randomised trial

“…[31] There is uncertainty over the role of HIV in the infectiousness of pulmonary tuberculosis, particularly with immune reconstitution due to ART. [32] This is partly because of the lack of a robust test for diagnosis of recent TB infection in settings where community force of infection is high, and data suggesting that HIV infection may lead to a shorter duration of symptomatic pulmonary disease and with less cavitation and lower bacillary load in people living with HIV. [33] In a high-TB burden community, TST induration in a household contact may represent infection as a consequence of household exposure from an index case, infection from other community contacts, or both.…”

Patient support for tuberculosis patients in low-incidence countries: A systematic review

“…Of the 40 publications on TB patient support, 36 included treatment supervision options [ 9 , 28 , 39 – 48 , 30 , 49 , 50 , 52 – 54 , 56 – 60 , 31 , 62 , 64 – 67 , 32 , 33 , 35 – 38 ] (19 as the sole patient support intervention [ 9 , 29 , 39 , 41 , 42 , 45 , 48 , 50 , 58 , 64 , 30 – 33 , 35 – 38 ]), 12 included SE support [ 34 , 43 , 61 , 62 , 46 , 47 , 52 , 53 , 56 , 57 , 59 , 60 ] (1 as the sole intervention [ 61 ]), 11 included PE support [ 34 , 40 , 62 , 51 , 53 – 57 , 59 , ...…”