Retrospective survey of chronic Q fever in Japan by using PCR to detect Coxiella burnetii DNA in paraffin-embedded clinical samples.

We used PCR to detect Coxiella burnetii DNA in paraffin-embedded tissues obtained from patients with chronic endocarditis in which the etiological agent had been unknown. On the basis of the published nucleotide sequence of the C. burnetii htpB gene, primers were chosen to produce an amplified fragment of 285 bp. A total of 60 samples from 56 patients were tested for the presence of C. burnetii DNA. Five samples from four patients were found to be positive. All of the amplified DNA fragments possessed a TthHB8I restriction site, as predicted from the published sequence of C. burnetii. In one of the four positive patients, rickettsia-like particles were found in sections of tissue stained by Gimenez's method. This is the first report of chronic Q fever in Japan.