Diagnosis

Diagnosis of rabies is generally made clinically.

Fluorescent antibody has been used to detect rabies antigen in tissue e.g. - nuchal skin biopsy - viral antigens or RNA detected at the base of hair follicles containing peripheral nerves, in salivary secretions, in brain tissue (post mortem)

Negri bodies are detected in about 90% of patients with rabies at post-mortem.

Clinical cases can be confirmed by the presence of one or more of the following laboratory criteria:

• presence of viral antigens
• isolation of virus in cell culture or in laboratory animals
• presence of viral specific antibodies in the cerebrospinal fluid or in the serum of an unvaccinated person
• presence of viral nucleic acids detected by molecular methods in samples (for example, brain biopsy sample, skin, saliva, concentrated urine) collected post mortem or when the patient is alive (1).

Reference:

• (1) Crowcroft NS, Thampi N.The prevention and management of rabies. BMJ. 2015;350:g7827.