Laboratory diagnosis of rabies in an endemic country: Progress and challenges on the path to elimination

Rabies is a fatal zoonotic disease, predominantly transmitted through dog bites. With persistently high endemicity, India launched a National Action Plan in 2021 aligned with WHO's "Zero by 2030″ goal and declared rabies a notifiable disease. Laboratory confirmation is critical to achieving elimination targets.

To retrospectively analyse the clinical and diagnostic characteristics of samples received for rabies diagnosis or post-vaccination antibody titre estimation.

A five-year (2018-2022) audit of laboratory records was conducted at a national rabies referral laboratory in a public neurocare centre in South India. Demographic and clinical profiles of suspected rabies cases and individuals tested for post-vaccination seroconversion were evaluated.

Of 790 clinical samples from 317 suspected cases, cerebrospinal fluid (38.6 %) was the most frequently received, followed by serum (27.6 %) and saliva (20.5 %). Laboratory confirmation was achieved in 41.9 % of cases using real-time PCR for rabies RNA detection and/or the rapid fluorescent focus inhibition test (RFFIT) for detection of neutralising antibodies. Among confirmed cases, males predominated (81.2 %), and children under 10 years accounted for 42.1 % of cases. Additionally, 2056 sera following pre- or post-exposure prophylaxis were tested by RFFIT, with 90 % demonstrating adequate virus-neutralizing antibody response.

The study highlights key trends in rabies diagnosis, epidemiology, and prophylaxis. Greater awareness among clinicians regarding optimal sample selection, limitations of antemortem testing, and the utility of postmortem brain sampling is essential to strengthen laboratory-based surveillance.