As diagnosis based on clinical ground alone is difficult and often unreliable; it is recommended to confirm a clinical case of rabies through the use of laboratory-based techniques. For post mortem diagnosis, the gold-standard diagnostic technique is to detect rabies virus antigen in infected tissues, preferably brain smears or touch impressions collected from a biopsy, by fluorescent antibody test (FAT). FAT is recommended by WHO and in 95-99% of cases, gives reliable results on fresh specimens within a few hours. Other methods for detection of lyssavirus antigens such as direct rapid immunohistochemistry tests are proven to have sensitivity and specificity comparable to the FAT. WHO recommends further development of direct rapid immunohistochemistry tests as an alternative to the FAT for improved decentralized laboratory-based surveillance in endemic areas.