Laboratory Diagnosis in Animals - Rabies Virus Infection

Laboratory Diagnosis in Animals

Laboratory diagnosis of rabies in dogs and other animals is useful to assess the risk of infection and to monitor postexpo-sure prophylaxis in humans bitten by the animals.

◗ Specimens

The brain of the dead animal is the specimen of choice. The brain is collected carefully from the dead animal. Part of the specimen is collected in 50% glycerol saline (preservative) for isolation of virus. The other part of the brain including the hip-pocampus and cerebellum (abundant in Negri bodies) is col-lected in Zenkers’ fixative for demonstration of Negri bodies.

◗ Microscopy

Impression smears of the brain tissue are stained by Seller’s technique for demonstration of Negri bodies. This is still a useful method in the laboratories lacking facilities for cell cul-ture and antigen detection methods.

◗ Direct antigen detection

Demonstration of viral antigens in the infected brain tissue and in saliva of the animal by DFA is a useful method for diagnosis of rabies in animals. Detection of antigen in the saliva shows whether the animal was excreting the virus in the saliva or not.

◗ Isolation of the virus

Viruses can be isolated from animal brain issue and saliva by culture in cell lines or in animals, as described earlier for diag-nosis of human rabies.