The small round red 10 micron inclusion seen here in the cytoplasm of a Purkinje cell is a Negri body indicative of rabies infection, typically acquired from the bite of an infected animal. Both urban (usually dogs) and sylvatic (often fox, mongoose, bat) animal populations provide a reservoir. The rabies virus present in saliva of an infected animal is introduced into a wound, typically on an extremity. The viral particles begin replication in skeletal muscle, but then spread to peripheral nerve and track centrally to the brain, where replication occurs in grey matter. Viral particles may then track distally via autonomic nerves to other tissues; those that track to salivary gland provide a means for infecting other hosts. The incubation period varies from days to months, depending upon the amount of virus, distance of nerves travelled, and host reponse. Persons at risk and pets can be immunized with a rabies vaccine. Following exposure, antirabies antiserum must be administered because recovery is rare. Diagnosis of rabies is made by examination of CNS tissues (hippocampus and cerebellum are good areas to look) with a fluorescent antibody stain.
There were 19 correct entries out of 82 total entries for case 48.
| Our winner is: Dr. Olgun Kontas of Kayseri, TURKEY
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