Rabies

Test code: S0116 - Ultrasensitive qualitative detection of rabies virus by reverse transcription real time polymerase chain reaction

Rabies virus, a nonsegmented, negative-stranded RNA virus, is a member of the Rhabdoviridae family. This family includes at least three genera of animal viruses, Lyssavirus, Ephemerovirus, and Vesiculovirus. The genus Lyssavirus includes rabies virus, Lagos bat virus, Mokola virus, Duvenhage virus, European bat virus 1 & 2 and Australian bat virus.

Rabies virus can cause fatal acute encephalitis in all mammalian hosts, including humans, dogs, cats, ferrets, pigs, livestock and many other species. However, only a few species are important as reservoirs for the disease. In the United States, several distinct rabies virus variants have been identified in raccoons, skunks, foxes, coyotes and several species of insectivorous bats.

Transmission of rabies virus usually begins when an uninfected animal contacts the saliva of an infected host animal. Various routes of transmission have been documented, including contamination of mucous membranes (ie eyes, nose, and mouth) and even aerosol transmission. However, the most common mode of rabies virus transmission is a bite from an infected host animal.

Initial symptoms of rabies infection in animals include lethargy, fever, vomiting, and anorexia. Signs progress within days to cerebral dysfunction, ataxia, weakness, paralysis, seizures, difficulty breathing, difficulty swallowing, excessive salivation, abnormal behavior, aggression, and/or self-mutilation.

Serology testing has been used to diagnose rabies virus exposure in animals. Direct fluorescent antibody testing is most frequently used to diagnose rabies. This test requires brain tissue from the animal suspected of being rabid. The test can only be performed post-mortem and is not suitable for testing live animals that may have contacted the virus. However, since animals may have had prior exposure to the virus, serology testing may not be specific in confirming the current presence of the virus. An extensive and time-consuming serology titering study may be required to prove the animal’s recent exposure.

Molecular detection by PCR is a rapid, sensitive and specific method to identify the presence of the rabies virus in a sample. The PCR test can be performed on saliva, spinal fluid or a bite lesion swab or biopsy.

See the US Centers for Disease Control (CDC) rabies website at http://www.cdc.gov/rabies/ for additional information on the diagnosis of rabies.

Utilities:

• Confirm the disease causing agent
• Identify rabies carriers
• Ensure that animal groups and populations are free of rabies virus
• Early prevention of spread of the virus among animals
• Minimize human exposure to the virus
• Safety monitoring of biological products that derive from animals

References:
http://www.cdc.gov/rabies/ (Centers for Disease Control and Prevention’s rabies information website)

Specimen requirements: Buccal swab of suspected host animal, or 0.5 ml of cerebrospinal fluid, or 0.5 ml of fresh brain stem tissue, shipped overnight at room temperature.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative reverse transcription real time PCR

Normal range: Nondetected