Lack of association between Kawasaki syndrome and infection with Rickettsia conorii, Rickettsia typhi, Coxiella burnetii or Ehrlichia phagocytophila group

BACKGROUND.The etiology of Kawasaki syndrome (KS) is unknown. Rickettsiae, intracellular microorganisms that invade the vascular endothelium, might cause KS. OBJECTIVES.To investigate whether there is an association between KS and infection with Rickettsia conorii, Rickettsia typhi, Coxiella burnetii or Ehrlichia phagocytophila group. METHODS.All children who were diagnosed with KS at the University of Athens Second Department of Pediatrics from December, 1999, through November, 2000, were prospectively studied. Paired serum specimens were obtained from all patients and antibody titers against R. conorii, R. typhi, C. burnetii and E. phagocytophila group were assessed by microimmunofluorescence assay. RESULTS.Eleven children with a median age of 2.5 years were included in the study. A 15-month-old child had a 4-fold rise of antibody titers against C. burnetii, which is indicative of acute Q fever. The patient had a history of recent exposure to possible sources of C. burnetii. The remaining patients tested negative for the presence of antibodies against R. conorii, R. typhi, C. burnetii and E. phagocytophila group. CONCLUSIONS.Our study does not provide serologic evidence that KS is the result of infection with R. conorii, R. typhi, C. burnetii or E. phagocytophila group. It is suggested that C. burnetii may cause a KS-like illness in young children.