Comparative study of histochemical staining of negri bodies using lendrum’s phloxine-tartrazine and fuchsin safranine blue staining methods
Abstract
Rabies is a fatal zoonotic disease caused by infection with the rabies lyssavirus, which causes 55,000 human deaths annually worldwide with 95% occurring in Africa and Asia. Diagnosis of rabies started way back in 1880 with inoculation of rabbits with the rabies virus. Today there are many methods used in rabies diagnosis from routine techniques such as Lendrum’s Phloxine-Tartrazine method and Fuchsin Safranine blue method to rapid techniques such as direct Fluorescent Antibody Test (dFAT), Rapid immunodiagnostic test (RIDT) and others with Fluorescent Antibody Test as a gold standard. However, dFAT is expensive and requires experienced personals as well as special equipment which are not usually available in developing countries such as Uganda. The aim of this study was to assess the histochemical staining of Negri bodies using Fuchsin Safranin blue method in comparison to Lendrum’s method and demonstrating the structure of Negri bodies. A total of thirty achieved rabies suspected brain samples were sectioned and stained with Lendrum’s Phloxine-Tartrazine method and Fuchsin Safranine blue method. The stained sections were observed under a light microscope at x40 for the presence of Negri bodies. Out of 30 brain samples, 17 and 12 were found to be positive for Lendrum’s Phloxine-Tartrazine method and Fuchsin Safranin blue staining method respectively. The sensitivity, specificity, predictive value of positive results and predictive value of negative results of Fuchsin Safranin blue staining method in relation Lendrum’s Phloxine-Tartrazine method was found to 70.1%, 100%, 100% and 72.2% respectively. In conclusion, the sensitivity of Fuchsin Safranine blue method for rabies is low in relation to Lendrum’s method, Fuchsin Safranine blue method has a high specificity for rabies and Lendrum’s method gives the best picture of Negri bodies. Therefore Lendrum's method is recommended for diagnosis of rabies and demonstration of Negri bodies in brain samples to confirm rabies.