An illness most commonly characterized by acute onset and fever,
usually accompanied by myalgia, headache, and petechial rash (on the palms and
soles in two-thirds of the cases)
Laboratory criteria for diagnosis
Fourfold or greater rise in antibody titer to the spotted
fever group antigen by immunofluorescent antibody (IFA), complement fixation
(CF), latex agglutination (LA), microagglutination (MA), or indirect hemagglutination
(IHA) test, or a single titer greater than or equal to 64 by IFA or greater
than or equal to 16 by CF
Demonstration of positive immunofluorescence of skin lesion
(biopsy) or organ tissue (autopsy)
Isolation of Rickettsia rickettsii from clinical
specimen
Case classification
Probable: a clinically compatible
case with supportive serology (fourfold rise in titer or a single titer greater
than or equal to 320 by Proteus OX-19 or OX-2, or a single titer greater
than or equal to 128 by LA, IHA, or MA test)