Advances in the Diagnosis of Hiv-associated Tuberculosis

HIV-associated tuberculosis (HIV-TB) remains a global public health challenge, with the major burden being borne by countries in low-resource settings. If World Health Organization targets to reduce TB deaths by 95% and new cases by 90% are to be met by 2035, major improvements in diagnostic strategies are among the most pressing needs. HIV coinfection presents particular challenges in the diagnosis of TB due, for example, to the relatively low mycobacterial burden in sputum specimens and rapid dissemination beyond the lungs. Low and middle-income countries still typically rely on traditional diagnostics such as chest radiology and sputum microscopy, which lack sufficient accuracy. Desired characteristics for an HIV-TB diagnostic test are well described and include the ability to test a wide variety of clinical samples, diagnose extra-pulmonary TB, have good accuracy to detect low mycobacterial burden disease, and be deployable at the peripheries of healthcare systems. Following a long period of under-investment in TB research, development of TB diagnostics has progressed rapidly over the past decade and the technology landscape looks much more promising. This article will summarise advances in diagnostics that are particularly relevant to HIV-TB. The Xpert® MTB/RIF and DetermineTM TB LAM assays have the most evidence assessing their use in HIV-TB. In addition to nucleic-acid amplification tests and antigen detection we will review new diagnostic technologies. Finally, we discuss whether use of empirical TB treatment offsets the potential impact and reduces the need for new diagnostics.