Full Length Research Paper

Prevalence and diagnostic aspects of sputum smear positive tuberculosis cases at a tertiary care institution in Rwanda

Claude Mambo Muvunyi^1,3*, Florence Masaisa^1,3, Claude Bayingana¹, Andre Musemakweri², Leon Mutesa¹ and Teresa Carbonell Hernandez^1,4

¹Department of Clinical Biology, Centre Hospitalier Universitaire-Butare, National University of Rwanda, Butare, Rwanda.

²Department of Internal Medicine, Centre Hospitalier Universitaire-Butare, National University of Rwanda, Butare, Rwanda.

³Department of Clinical Chemistry, Microbiology and Immunology, Ghent University Hospital, Belgium.

⁴Department of Microbiology, Teaching Hospital "J. M. Aristegui", Matanzas, Cuba.

*Corresponding author. E-mail: cmuvunyi@nur.ac.rw Tel: +250 0788493814.

Fax: +250 530 328.

Accepted 12 October, 2009

   Abstract

Approximately one third of the world’s population is infected with Mycobacterium tuberculosis and 9.27 million new cases of TB occurred in 2007. Developing countries disproportionately shoulder the global burden of disease with the highest estimated rates in the world, with an estimated 55% of global cases in Asia and 31% in the African region. The incidence of new sputum smear positive in Rwanda through recent national survey was an estimated 162 per 100 000 population. The aim of our study was to evaluate the prevalence of smear positive pulmonary TB among patients at the University of Butare Teaching Hospital, a tertiary health facility in South province, Rwanda.  In addition, some aspects of the performance of the pulmonary TB diagnosis are discussed. The overall prevalence of sputum smear positive cases were 17.3% (63 0f 364) and most of the positive patients were within the age range 15 - 44 years. The highest percentage of TB was seen in the age group of 15 - 24 years compared with the lowest percentages in the age group below 14 years and above 45 years. A total of 63 (17.3%) suspects were found to have at least one positive. Of these, 56 (88.9% of those with one or more positive smears and 92% of those who fulfilled the case definition) were detected from the first specimen and 7 (11.1%) were positive on the second specimen but not the first. The third specimen did not have any additional diagnostic value for the detection of AFB. The prevalence of sputum smear positive cases of 17.3% increases with age up to the age 44 years. Our result show that examining two sputa smears was sufficient for the detection of AFB in our laboratory. Further research involving different laboratories from all of the regions of Rwanda is needed to reassess these findings.

Key words: Smear positive tuberculosis, prevalence, diagnostic aspects, Rwanda.