Detection of Rabies Virus Antigen by Fluorescent Antibody Test and Rapid Immunochromatographic Assay in a Pregnant Goat from Salem, Tamil Nadu, India

Rabies in small ruminants is underdiagnosed in India because a bite history is often absent and clinical signs may mimic metabolic disorders of late pregnancy. This study reports a case of rabies in a pregnant doe, confirmed by the fluorescent antibody test and supported by two complementary techniques. A doe at approximately 4.5 months’ gestation was presented to the Veterinary Clinical Complex, Veterinary College and Research Institute, Salem, Tamil Nadu, with inappetence, aggression and recumbency. Blood and urine glucose were estimated ante-mortem. The doe exhibited aggression, biting, eye rubbing, continuous leg licking, yawning, bleating and sternal recumbency, with no reported history of a dog bite. The doe died on the day of presentation. Blood glucose was 103 mg/dL, accompanied by glucosuria. Postmortem brain tissue collected through the occipital foramen was examined using the fluorescent antibody test (FAT), a rapid immunochromatographic lateral flow assay (LFA) and modified Van Gieson staining. FAT revealed apple-green intracytoplasmic fluorescence, the LFA showed distinct control and test bands and Negri bodies were identified by modified Van Gieson staining. Rabies was confirmed by FAT; the LFA result was concordant and the Negri bodies provided supportive evidence. Hyperglycaemia with glucosuria in an anorectic pregnant doe was observed in this case; however, this finding is non-specific, and its diagnostic value needs to be evaluated in a larger number of cases. The LFA offers rapid, field-level detection and can complement FAT, the gold standard method.