A group of guinea pigs carrying a chronic streptococcus cervical lymphadenitis has been studied. The chronic disease may be transmitted with pure cultures of streptococci isolated from the naturally occurring abscesses. Its probable mode of transmission under natural conditions was shown to be the ingestion of the infective agent.
The spontaneous appearance of an acutely fatal variant was observed. Infection with the chronic strains protected animals against the highly virulent strain. Such immunity could not be passively transferred to either mice or guinea pigs, nor could any opsonizing, precipitating, or bactericidal antibody be associated with it. The presence of allergy could not be correlated with this immunity.
The dissociation of the chronic and acute strains was investigated and non-invasive phases isolated. No precipitin reaction attributable to an antigenic virulence factor could be demonstrated. No protection was obtained with vaccines or aggressins.