Correlation of Rickettsial Titers, Circulating Endotoxin, and Clinical Features in Rocky Mountain Spotted Fever

Lisa G. Kaplowitz, James V. Lange, Janet J. Fischer, David H. Walker

Research output: Contribution to journalArticle

33 Scopus citations


Blood rickettsial titers, skin biopsy results, and circulating endotoxin measurements were correlated with the clinical course of disease in patients with Rocky Mountain spotted fever (RMSF). Nine of 11 patients with documented RMSF had Rickettsia rickettsii isolated from plasma samples. Of the eight patients in whom rickettsial titers were measured, seven had 100.7 to 101.2 median tissue culture infective doses (TCID50) per milliliter; all seven had mild to moderately severe disease. One patient with fulminant, fatal untreated RMSF had 103 TCID50/mL of postmortem plasma. Two patients from whom rickettsiae were not isolated had positive direct immunofluorescent stains of skin biopsy material for R rickettsii. Circulating endotoxin was present in two patients, one with documented rickettsemia and one with a positive skin biopsy alone. Only low levels of circulating rickettsiae are present in patients with moderately severe disease. Measurement of plasma endotoxin is not useful in the early diagnosis of RMSF.

Original languageEnglish (US)
Pages (from-to)1149-1151
Number of pages3
JournalArchives of Internal Medicine
Issue number6
StatePublished - Jun 1983
Externally publishedYes


ASJC Scopus subject areas

  • Internal Medicine

Cite this