Abstract
BackgroundThe Mycobacterium tuberculosis complex (MTBC) consists of causative agents of both human and animal tuberculosis and is responsible for over 10 million annual infections globally. Infections occur mainly through airborne transmission, however, there are possible indirect transmissions through a faecal-oral route which is poorly reported. This faecal-oral transmission could be through the occurrence of the microbe in environments such as wastewater. This manuscript, therefore, reviews the source and fate of MTBC in the wastewater environment, including the current methods in use and the possible risks of infections.ResultsThe reviewed literature indicates that about 20% of patients with pulmonary TB may have extra-pulmonary manifestations such as GITB, resulting in shedding in feaces and urine. This could potentially be the reason for the detection of MTBC in wastewater. MTBC concentrations of up to 5.5 × 105 (±3.9 × 105) copies/L of untreated wastewater have been reported. Studies have indicated that wastewater may provide these bacteria with the required nutrients for their growth and could potentially result in environmental transmission. However, 98.6 (± 2.7) %, removal during wastewater treatment, through physical-chemical decantation (primary treatment) and biofiltration (secondary treatment) has been reported. Despite these reports, several studies observed the presence of MTBC in treated wastewater via both culture-dependent and molecular techniques.ConclusionThe detection of viable MTBC cells in either treated or untreated wastewater, highlights the potential risks of infection for wastewater workers and communities close to these wastewater treatment plants. The generation of aerosols during wastewater treatment could be the main route of transmission. Additionally, direct exposure to the wastewater containing MTBC could potentially contribute to indirect transmissions which may lead to pulmonary or extra-pulmonary infections. This calls for the implementation of risk reduction measures aimed at protecting the exposed populations.
Highlights
The Mycobacterium tuberculosis complex (MTBC) consists of causative agents of both human and animal tuberculosis and is responsible for over 10 million annual infections globally
The reviewed literature showed that MTBC could potentially survive in wastewater for months, this could be attributed to their cell physiology and ecology
Wastewater treatment has been shown to reduce the concentration of several bacteria, including these MTBC members, there are a significant number of reports on their occurrence in treated wastewater
Summary
The Mycobacterium tuberculosis complex (MTBC) consists of causative agents of both human and animal tuberculosis and is responsible for over 10 million annual infections globally. Infections occur mainly through airborne transmission, there are possible indirect transmissions through a faecal-oral route which is poorly reported. The main infection route for TB has been reported to be through exposure to aerosols from infectious patients [17,18,19,20,21,22] This fundamentally shows the airborne transmission of pulmonary TB and is currently widely accepted as the primary mechanistic transmission route [23, 24]. The clinical and pathological observations in the infected animals were similar to those found in guinea pigs infected via the respiratory or subcutaneous routes This shows the possible oral transmission of TB in exposed individuals
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