Rabies encephalitis following fox bite--histological and immunohistochemical evaluation of lesions caused by virus.

Rabies caused by fox bite is uncommon, most cases being caused by bite of rabid dogs (95%). We report a 45-year-old lady with rabies encephalomyelitis caused by bite of a rabid wild fox (Vulpes vulpes), a species prevalent in the Deccan plateaus of Central India. Though foxes are known to be susceptible to rabies, literature on the pathological changes caused by fox bite rabies in humans is scarce. Unlike the mild histological alterations described in canine rabies, a florid encephalitic process evolved in fox bite rabies, in our case, with intense microglial reaction, neuronophagia and perivascular inflammatory infiltrates despite clinical manifestation as a paralytic rabies. Immunostaining using polyclonal antibodies to the rabies viral nucleocapsid antigen and to the whole virion demonstrated high viral load within neurons with extensive spread along dendritic arborization and axonal tracts. Genomic sequence analysis demonstrated close homology with canine virus strain with only minor variations.