The presence of foci of Rickettsia conorii infection in China

Abstract

China is not considered as an endemic area of Rickettsia conorii, so there is no routine clinical way to diagnose this infection. This study aims to determine whether 2 febrile patients who had a tick bite in East China were indeed infected with R. conorii. The citrate synthase gene (gltA) was amplified with universal rickettsial primers by real-time fluorescent PCR from the patients’ blood samples. Nested PCR was used to amplify the outer membrane protein A gene (ompA) for positive specimens. PCR products were further identified and analyzed through nucleic acid sequencing. Positive amplification of the gltA and ompA genes was found in both patients. The nucleotide sequences (303 bp) of the ompA gene of the 2 patients had high homology (99%) with the R. conorii Indian tick typhus strain in GenBank. A more than 4-fold increase in IgG against R. conorii provided supportive evidence of SFG Rickettsia infection. And the rapid recovery after doxycycline treatment also supported a rickettsial cause for the disease. Physicians in East China should be aware of human infections with R. conorii. PCR-based diagnostic methods offer a rapid and precise way to diagnose rickettsiosis, improving patient identification and management.