An approach to the problems of diagnosing and treating adult smear-negative pulmonary tuberculosis in high-HIV-prevalence settings in sub-Saharan Africa

Abstract

The overlap between the populations in sub-Saharan Africa infected with human immunodeficiency virus (HIV) and Mycobacterium tuberculosis has led to an upsurge in tuberculosis cases over the last 10 years. The relative increase in the proportion of notified sputum-smear-negative pulmonary tuberculosis (PTB) cases is greater than that of sputum-smear-positive PTB cases. This is a consequence of the following: the association between decreased host immunity and reduced sputum smear positivity; the difficulty in excluding other HIV-related diseases when making the diagnosis of smear-negative PTB; and an increase in false-negative sputum smears because of overstretched resources. This article examines problems in the diagnosis and treatment of smear-negative PTB in high-HIV-prevalence areas in sub-Saharan Africa. The main issues in diagnosis include: the criteria used to diagnose smear-negative PTB; the degree to which clinicians actually follow these criteria in practice; and the problem of how to exclude other respiratory diseases that can resemble, and be misdiagnosed as, smear-negative PTB. The most important aspect of the treatment of smear-negative PTB patients is abandoning 12-month "standard" treatment regimens in favour of short-course chemotherapy. Operational research is necessary to determine the most cost-effective approaches to the diagnosis and treatment of smear-negative PTB. Nevertheless, substantial improvement could be obtained by implementing the effective measures already available, such as improved adherence to diagnostic and treatment guidelines.