Diagnostic delay and the potential of two fusion antigens for the diagnosis of Tuberculosis in Northeast Ethiopia

Abstract

Background: Tuberculosis (TB) is a major public health problem in the Horn of Africa, Ethiopia having the highest burden which is related to continued transmission of the disease to uninfected individuals as a result of delayed diagnosis and treatment. Early detection and effective treatment are pre-requisites to bring the high TB load under control. In this regard, early health seeking action from patients¡¦ side and prompt diagnosis as well as initiation of treatment from health system¡¦s side are essential steps. Currently, efforts are underway to identify simple, rapid and accurate diagnostic tests for TB. The aim of this study was to evaluate the potential of rESAT-6-CFP-10 and rƒÑ-crystallin-MPT-83 in the diagnosis of pulmonary TB. Besides, we have assessed delay in the diagnosis and treatment of TB patients in Northeast Ethiopia. Methods: To evaluate the two antigens, 328 pulmonary TB suspects who reported to selected health facilities were included consecutively. Sputum and serum samples were collected from all participants. Culture, which was used as reference standard, was done on all sputum samples. ELISA was run on 204 serum samples using the two antigens. To assess delay, 216 TB patients who visited DOTS clinics of two health facilities in Afar Region were included consecutively from September 2009 to February 2010. Time from onset of symptoms till first consultation of formal health providers (patients¡¦ delay) and time from first consultation till initiation of treatment (health system¡¦s delay) were analyzed. Results: The sensitivity and specificity of rESA-6-CFP-10 antigen were 57.3% and 71.3%, respectively whereas the sensitivity and specificity of rƒÑ-crystallin-MPT-83 antigen were 20.2% and 92.2%, respectively. The median patients¡¦ and health system¡¦s delay were 20 and 33.5 days, respectively. The median total delay was 70.5 days with a median treatment delay of 1 day. Self-treatment and first visit to non-formal health providers were found to be independent predictors of patients¡¦ delay. On the other hand, having extra-pulmonary TB and a first visit to health posts/clinics, health centers and private clinics were found to be independent predictors of health system¡¦s delay. Conclusion: The performance of the two antigens was low and therefore, they can¡¦t be used as a substitute or supplementary test in the study area. There is a long delay in the diagnosis and initiation of treatment and this was mainly attributable to the health system. Therefore, the quest for simple, accurate and rapid tests should be a priority in TB control programmes.