A comparative study of the fluorescent antibody test for rabies diagnosis in fresh and formalin-fixed brain tissue specimens.

Many diagnostic methods have been used to detect rabies virus antigen. The preferred method for routine diagnosis of rabies in fresh or frozen brain tissues is the fluorescent antibody test (FAT). In this study, the FAT was used to evaluate the rabies status of fresh/frozen brain specimens from more than 800 rabies-suspected cases, in more than 14 different species of animals. A comparable brain specimen from each case was fixed in 10% buffered formalin and examined by the FAT. The evaluation of rabies status between fresh and formalin-fixed tissues was in agreement in more than 99.8% of the cases. When fresh tissue is not available for testing, these results validate the use of this procedure for routine diagnosis of rabies in formalin-fixed brain tissues.