How do you test a rat for rabies? - briefly
Testing is performed by obtaining brain tissue after euthanasia and applying a direct fluorescent antibody assay, the gold‑standard method for rabies detection; molecular techniques such as PCR on saliva or tissue may be used as supplementary diagnostics.
How do you test a rat for rabies? - in detail
Testing a rodent for rabies requires strict biosafety, accurate sample collection, and reliable laboratory techniques.
The animal should be humanely euthanized under approved protocols. Personnel must wear disposable gloves, a fluid‑resistant gown, eye protection, and a face shield; work must occur in a biosafety level 2 cabinet.
Brain tissue provides the definitive diagnostic material. After euthanasia, the skull is opened with a sterile scalpel. The following regions are removed with a brain spatula:
- hippocampus
- cerebellum
- brainstem (including the medulla oblongata)
Samples are placed in a sterile, leak‑proof container, kept on ice, and shipped to a reference laboratory within 24 hours. Packaging must comply with the UN3373 “Biological Substance, Category B” regulations.
Laboratories employ three primary methods:
- Direct Fluorescent Antibody (DFA) test – brain impressions are stained with fluorescein‑labeled anti‑rabies antibodies and examined under a fluorescence microscope. Positive fluorescence in neuronal cells confirms infection.
- Reverse Transcription Polymerase Chain Reaction (RT‑PCR) – extracts viral RNA from homogenized brain tissue, amplifies rabies‑specific gene segments, and detects viral genome with high sensitivity.
- Virus isolation in cell culture – homogenates inoculated onto susceptible cell lines (e.g., neuroblastoma cells) are observed for cytopathic effect and confirmed by DFA on harvested cells. This method is slower but provides live virus for further characterization.
Serological assays are unsuitable for rodents because they rarely develop detectable antibody titers before death.
Result interpretation follows established criteria: a positive DFA or RT‑PCR result indicates active rabies infection; a negative DFA must be confirmed by a second test (RT‑PCR or virus isolation) to rule out false negatives.
Confirmed cases are reported to public health authorities, triggering post‑exposure prophylaxis recommendations for any individuals exposed to the animal’s saliva or neural tissue. Documentation includes species, collection date, test methods, and final diagnosis.