Background: Nigeria is ranked in the top 5 for tuberculosis deaths worldwide. Previous studies have suggested other forms of Mycobacteria other Mycobacterium tuberculosis that causes clinical tuberculosis in animals and humans is prevalent in Nigeria especially in TB/HIV co-infections with weakened immune system.
Methods: 1,835 suspected cases of pulmonary tuberculosis were recruited and screened for Mycobacterium with an algorithm that consisted of smear microscopy, culture, tuberculosis antigen MPT64 detection, and molecular line probe assay. HIV status was done as standard of care.
Results: 466 (29%) of the 1603 patients screened had culture confirmed pulmonary Mycobacterial infection. Of this, 375 (80%) were due to strains of Mycobacterial tuberculosis complex, and 69 (15%) due to Non-tuberculosis mycobacterium, 127 of 444 (29%) had co-infection with HIV with a rate of 29% among MTB complex and 37% among NTM. Cases resistant to at least one drug were more likely to have co-infection with HIV compared to cases without any resistance (OR=3.6, 1.5-8.8; p=0.0039). The NTM cases were more likely to have a pattern of occurrence that coincided with the calendar month of Harmattan (intense dust storm in the November to February time period) (OR=2.0, 1.1-3.8; p=0.0209).
Conclusions: While Mycobacterium TB complex predominates, M. africanum is frequent and anti-TB drug resistance is prevalent. The high frequency (15%) with clinical pulmonary TB due to NTM linked to seasonal dust exposure and HIV presents a novel public health challenge. Introduction of molecular detection and screening assays to address the rapid identification of NTM and drug resistant TB is a high priority for strengthening the public health response.
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