Additional Highly Virulent Strains of Rocky Mountain Spotted Fever Virus Isolated in Georgia

Abstract
Strains of Rocky Mt. spotted fever isolated in 1940 from human cases and ticks (Dermacentor variabilis) were found to be as virulent as a previously isolated tick strain in 1939. The fatality rate in guinea pigs for the human strains were 73.9 and 69.9%; the tick strains 71.4%, the 1939 tick strain 70.4%.
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