CLINICAL DESCRIPTION
A tick borne febrile illness most commonly characterized by acute onset, and usually accompanied by myalgia, headache, and a petechial rash (on palms and soles in two thirds of the cases). In the northeastern, United States, the dog tick is responsible for most transmissions, although history of tick exposure is not always found. The incubation period is 3 to more than 14 days.

CASE CLASSIFICATION

1. CONFIRMED
   
   A clinically compatible case AND one or more of the following laboratory tests:
   
   • Fourfold or greater rise in antibody titer to Rickettsia rickettsii antigen by immuno-fluorescence antibody (IFA), complement fixation (CF), latex agglutination (LA), microagglutination (MA), or indirect hemagglutination antibody (IHA) test in acute- and convalescent-phase specimens ideally taken greater than or equal to 3 weeks apart, OR
     
   • Positive PCR assay to Rickettsia rickettsii, OR
     
   • Demonstration of positive immunofluorescence of skin lesion biopsy or organ tissue, OR
     
   • Isolation of Rickettsia rickettsii from a clinical specimen.
     
     
2. PROBABLE
   
   A clinically compatible case AND:
• · Single IFA serologic titer of greater than or equal to 64; OR
  · Single CF titer of greater than or equal to 16; OR
  · Fourfold rise in titer or a single titer greater than or equal to 320 by Proteus OX-19 or OX-2; OR
  Single titer greater than or equal to 128 by an LA, IHA, or MA test.
  
  
3. POSSIBLE
   
   Initially reported on the basis of clinical diagnosis, until confirmation is obtained or probable case status is established; no possible case qualifications are retained.

What you should know about Rocky Mountain Spotted Fever?