Isolation of Streptococci in a Study of the Epidemic of Encephalitis in St. Louis

Abstract

In a previous report 1 the consistent demonstration of streptococci in the spinal fluid obtained from patients during the active stage of encephalitis; the isolation of a streptococcus having peculiar cataphoretic velocity and virulence from the nasopharynx, spinal fluid, and brain; the specific agglutinability of the streptococcus by the encephalitis antistreptococcus serum, and by the serum of convalescent patients; and the production in rabbits of the more important acute clinical and pathological manifestations of the disease, have been recorded. Since then the streptococcus has been isolated from the blood of 5 of 7 patients during the active stage of the disease, it has been found in the nasopharynges and spinal fluids in additional cases, and a large proportion of contacts and non-contacts in the epidemic zone have been found to be carriers of this streptococcus. Thus, the streptococci of 52 (81%) of the different strains isolated from 64 persons in the active stage of the disease (2 to 10 days) had mainly neurotropic cataphoretic velocity. The streptococci of 78 (52%) of the different cultures from 149 well persons and patients with diseases other than encephalitis, in the epidemic zone, had a similar neurotropic cataphoretic velocity. The results in both of these groups were in sharp contrast to the results in 149 well persons and patients with diseases other than encephalitis, remote from the epidemic, in which the streptococci from only 39 (26%) had mainly neurotropic cataphoretic velocity.

Streptococci or diplococci have been demonstrated in or adjacent to the lesions of the brain, and in the sediment of spinal fluids of rabbits and monkeys that developed encephalitis following inoculation with the streptococcus, and with emulsions of the glycerolated brain in fatal cases, and in or adjacent to the lesions in the brains in several fatal cases.

The precipitin reaction with the encephalitis antistreptococcus serum and cleared nasopharyngeal washings, was positive in 78% of 69 active cases, and in 49% of 149 contact and non-contact controls residing in the epidemic zone, as compared with 14% of 159 well persons tested remote from the epidemic.