Time course of the levels of antibodies to Coxiella burnetii and detection of C. burnetii-DNA in three imported cases of acute Q fever

摘要

Three patients developed acute Q fever after returning from an inspection tour of farms and abattoirs to Australia. Serum levels of antibodies to Coxiella burnetii and the presence of C. burnetii-DNA in blood samples were examined for more than 100 days. Four-fold raises of IgM and IgG antibodies against C. burnetii phase 2 were observed within the first three weeks in all the three cases. Maximum titers of IgM and IgG antibodies were 1,024-2,048 and 512-4,096, respectively. According to the temporal diagnostic criteria of acute Q fever in the convalescent serum: the IgM titer of > or = 64 and IgG titer of > or = 512 against phase 2, patient A, B and C were determined to be antibody positive for 45, 199 and 122 days, respectively. The result suggests that this standard is practical and reasonable for diagnosis of acute Q fever. C. burnetti-DNA was detected in the sera and buffy coat samples of patient A who developed high fever, severe thrombocytopenia and liver disfunction, but not in those of patientB and C. This study provides useful information for optimization and standardization of Q fever diagnosis in Japan.