Molecular evidence of CandidatusRickettsia longicornii and a novel Rickettsiastrain from ticks in Southern China

Ticks and tick-borne rickettsial diseases have been gaining greater attention in China over the past decade. However, most published studies to date have occurred in Northern China, with limited investigations occurring in China’s southern provinces. As part of larger surveillance efforts, a cross-sectional survey was conducted in six sites at Guangdong, Guangxi and Yunnan investigating rickettsial infection in ticks. A total of 581 ticks were collected from hosts and screened via PCR, targeting rrs, gltA, ompB, sca4,and ompAgene fragments. Two of 12 Haemaphysalis formosensisticks were infected with novel Rickettsiastrain GD01, which was closest phylogenetically (97.3–98.9 % identity) to Rickettsia tamuraestrain AT-1, but not within the same clade. Another detected strain (GD02) shared similar identity, 99–100 % across four gene targets, to recently detected CandidatusRickettsia longicornii isolate ROK-HL727, with an overall prevalence of 12.5 % (71/569). The presence of such pathogens calls for increased public health attention and active surveillance in patients reporting recent tick bites.