An outbreak of post-vaccinal rabies (rage de laboratoire) in Fortaleza, Brazil, in 1960. Residual fixed virus as the etiological agent.

The repeated isolation of fixed rabies virus from the CNS tissues of victims of an acute and lethal outbreak of encephalomyelitis in Fortaleza, Brazil, in November 1960, following vaccination with a locally produced killed-virus anti-rabies vaccine of the Fermi type is considered as definitive evidence of the rabic etiology (vaccinal fixed-virus rabies, rage de laboratoire) of this outbreak. Eighteen persons were affected, all of whom died.The clinical picture of paralytic rabies was recognizable in all of these 18 patients. The well-marked characteristics of an acute infection permit the easy differentiation of the paralysis caused by fixed rabies virus from post-vaccinal accidents that occur as allergic reactions.The incriminated anti-rabies vaccine was found to contain fixed live rabies virus at a titre of 10(-3.0). After one year of storage under refrigeration, the vaccine still contained fixed rabies virus, at a titre of 0,2x10(-1.0).Subsequent laboratory studies tend to indicate that the curve of inactivation of fixed virus by phenol does not follow a linear function but rather resembles the curve of inactivation of poliomyelitis virus by heat and formol according to the Salk technique. It is suggested that the antigenicity of the so-called "killed-virus" anti-rabies vaccines is actually due to the presence in them of residual amounts of live virus.