The impact of HIV infection on tuberculosis transmission in a country with low tuberculosis incidence: a national retrospective study using molecular epidemiology

Abstract

Background HIV is known to increase the likelihood of reactivation of latent tuberculosis to active TB disease; however, its impact on tuberculosis infectiousness and consequent transmission is unclear, particularly in low-incidence settings. Methods National surveillance data from England, Wales and Northern Ireland on tuberculosis cases in adults from 2010 to 2014, strain typed using 24-locus mycobacterial-interspersed-repetitive-units–variable-number-tandem-repeats was used retrospectively to identify clusters of tuberculosis cases, subdivided into ‘first’ and ‘subsequent’ cases. Firstly, we used zero-inflated Poisson regression models to examine the association between HIV status and the number of subsequent clustered cases (a surrogate for tuberculosis infectiousness) in a strain type cluster. Secondly, we used logistic regression to examine the association between HIV status and the likelihood of being a subsequent case in a cluster (a surrogate for recent acquisition of tuberculosis infection) compared to the first case or a non-clustered case (a surrogate for reactivation of latent infection). Results We included 18,864 strain-typed cases, 2238 were the first cases of clusters and 8471 were subsequent cases. Seven hundred and fifty-nine (4%) were HIV-positive. Outcome 1: HIV-positive pulmonary tuberculosis cases who were the first in a cluster had fewer subsequent cases associated with them (mean 0.6, multivariable incidence rate ratio [IRR] 0.75 [0.65–0.86]) than those HIV-negative (mean 1.1). Extra-pulmonary tuberculosis (EPTB) cases with HIV were less likely to be the first case in a cluster compared to HIV-negative EPTB cases. EPTB cases who were the first case had a higher mean number of subsequent cases (mean 2.5, IRR (3.62 [3.12–4.19]) than those HIV-negative (mean 0.6). Outcome 2: tuberculosis cases with HIV co-infection were less likely to be a subsequent case in a cluster (odds ratio 0.82 [0.69–0.98]), compared to being the first or a non-clustered case. Conclusions Outcome 1: pulmonary tuberculosis-HIV patients were less infectious than those without HIV. EPTB patients with HIV who were the first case in a cluster had a higher number of subsequent cases and thus may be markers of other undetected cases, discoverable by contact investigations. Outcome 2: tuberculosis in HIV-positive individuals was more likely due to reactivation than recent infection, compared to those who were HIV-negative.

Diagnosis of extrapulmonary tuberculosis by ultrasound-guided biopsy: A retrospective comparison study

“…From the demographic aspects, several studies have reported similar findings that HIV co-infection and age (> 65 years old) contribute to EPTB infection ( Lakoh et al., 2020 ; Winter et al., 2020 ; Barreto-Duarte et al., 2021 ), consistent with our results. However, we found that males were more likely to have EPTB than females (OR 1.89, 95%CI 1.10-3.29, p = 0.021), which was not consistent with some previous studies ( Peto et al., 2009 ; Pang et al., 2019 ).…”

Comorbidity and drug resistance of smear-positive pulmonary tuberculosis patients in the Yi Autonomous Prefecture of China: a cross-sectional study

“…The 2263 patients with sputum smear positive TB were mainly Yi men aged 15-44 years, and sex characteristics were consistent with the previous reported male-to-female ratio of 2:1 1,4,29 . However, compared with other regions of China or other ethnic minorities with tuberculosis, these patients are generally younger [30][31][32][33] .…”

“…The occurrence of TB in the 15-44 age group may be related to increased social activity, exposing them to risk factors such as smoking, drinking, and HIV. In our survey, we also observed that the number of smokers, alcoholism, and HIV-positive people are higher than those in previous surveys 29,[34][35][36] . All these inconsistencies can be explained by approximately 80% of the Yi patients in the study group.…”

The role of employment-based exposure to hazardous substances in driving tuberculosis diagnosis among working-age men in South Africa

“…Thus, other reasons as to why this might be the case had to be explored. Upon, deeper inspection the study found that it might be plausible that HIV infections could be making men from the Western Cape more susceptible to TB diagnosis as it weakens the immune system, thus increasing the risk of TB in people with HIV compared to men from Gauteng, particularly among young men whose risk of HIV is high (15,16,17). This could be the case considering that the Western Cape's PrEP uptake was 0.3% in 2021 compared to 1% in Gauteng (15).…”