Detecting Sub-Clinical Tuberculosis in Face Masks Worn by People Living with HIV Attending Routine HIV Care at Parirenyatwa Group of Hospitals Opportunistic Infections Unit, Harare, Zimbabwe

Tuberculosis (TB) is a bacterial infection spread through inhaling tiny droplets from the coughs or sneezes of an infected person. It is associated with a dynamic spectrum of pathology between adequate containment and progression to active disease, hence it has three main stages of infection namely subclinical stage, latent infection stage and active TB disease stage. Individuals with subclinical tuberculosis (TB) represent a large proportion of all prevalent cases of TB, yet their contribution to Mycobacterium tuberculosis (Mtb) transmission is unknown. Subclinical TB has been increasingly recognised as a separate spectrum of the disease, and evidence on its transmissibility is, however, still inconclusive and unknown. Culture or Xpert MTB/ RIF positivity in bronchoalveolar lavage from sputum-negative or sputum-scarce patients suggests the presence of Mtb in the peripheral airways. This study, therefore, aimed to provide preliminary data on the clinically relevant role of face mask sampling as a novel diagnostic specimen for TB screening and diagnosis in asymptomatic HIV-positive patients. An exploratory cross-sectional study was conducted at Parirenyatwa Group of Hospitals (PGH) Opportunistic Infections (OI) unit, which was purposively selected because of its desirable characteristic of population diversity. A total of 160 asymptomatic HIV-positive individuals were enrolled between September and November 2022 and these were randomly sampled from people living with HIV (PLHIV) attending routine HIV care at PGH OI unit. Participants under the age of 18 were asked to provide parental/ guardian consent. Pretested interviewer administered questionnaires were used to collect data for the patients and a desk review of medical records was done for extra data extraction. Statistical analysis was done on the obtained data and various indicators used in the study. Out of the total 160 asymptomatic HIV-positive individuals who were assessed, Mtb was detected in 2.5% of the pulmonary TB (pTB) face mask samples, and all were Rifampicin resistance negative. All positive cases had been on antiretroviral therapy (ART) for less than one year, and all were at least 60 years old. Findings from this study suggests that subclinical TB contributes to transmission of pTB, and thus needs to be diagnosed and treated for effective progress towards TB elimination. The study also proved face mask sampling as an effective and alternative approach to understanding and diagnosing TB. It offers a simple, highly sensitive, inexpensive, non-invasive and easily deployable tool for the diagnosis of pTB, and stratification of transmission risk from individuals with pTB. This study supports the potential of face mask sampling as a clinical tool to enhance TB control programmes necessary for eradication of TB and provides an epidemiological tool to better characterise Mtb transmission within complex community settings. Widespread application will potentially reduce diagnostic uncertainty and enable improved case-finding with both individual and public health benefits.