Comparison of direct, Rapid Immunohistochemical Test Performance with Direct Fluorescent Antibody Test for rabies diagnosis in Ethiopia

Abstract

Background: Rabies continues to be a persistent and major public health problem for many developing countries. Rapid and accurate laboratory diagnosis is one of the basic elements in rabies control strategies. However, Laboratory diagnosis for animal and human rabies is severely constrained in much of the developing world including Ethiopia where rabies is endemic. Objective: To evaluate the performance of Direct, Rapid Immunohistochemical Test for rabies antigen detection from clinical samples in comparison with the Direct Fluorescent Antibody, gold-standard test. Method: The study was conducted from July, 2010- June, 2011 in Zoonoses Research Laboratory of Ethiopian Health and Nutrition Research Institute. During this study period a total of 200 brain tissue samples were collected from animals head submitted for routine rabies diagnosis. All the brain tissue samples were tested for rabies using Direct, Rapid Immunohistochemical Test, and Direct Fluorescence Antibody Test. Results: Above two-thirds (67.5%, 135 of 200) of the animal brain tissues examined using direct, Rapid Immunohistochemistry Test were found positive for rabies antigen that showed 100% sensitivity and specificity of direct, Rapid Immunohistochemistry Test compared to the results obtained by Direct Fluorescent Antibody test. Conclusion: The direct, Rapid Immunohistochemistry Test showed equivalent sensitivity and specificity as compared to Direct Fluorescent Antibody test under laboratory condition. Further study with large sample size and wide range of geographical representation of the country is needed to assess the ease of use and feasibility of this test at regional laboratories and under field conditions.