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Background. Rickettsia raoultii is frequently detected in multiple tick species, whereas human infection remains scarcely studied. Methods. A surveillance study was performed at 3 sentinel hospitals in China, to recruit participants with suspected tick exposure. Rickettsia raoultii infection was identified through polymerase chain reaction, followed by sequencing, and confirmed serologically. Isolation by cell culture was performed and the isolates were genome sequenced. Results. Twenty-six subjects were determined to have R. raoultii infection, including 7 with asymptomatic infection, 15 with mild to moderate illness, and 4 with severe illness. Common nonspecific manifestations in the 19 patients with mild to moderate or severe illness included fever (100%), malaise (95%), myalgia (58%), lymphadenopathy (53%), and nausea (42%). Only 5% of them had rash, and 16% had eschar. Scalp eschar and neck lymphadenopathy after a tick bite syndrome was only seen in 2 patients. Of the 4 patients with severe complications, 3 developed pulmonary edema, and 1 developed clouding of consciousness and lethargy. Frequent abnormalities of laboratory testing included leukopenia, thrombocytopenia, lymphopenia, neutropenia, hypoproteinemia, and elevated levels of total bilirubin, hepatic aminotransferases, lactate dehydrogenase, and creatine kinase. All the 19 patients recovered without sequelae after receiving doxycycline treatment. Two R. raoultii strains were isolated, and a significantly less degraded genome was observed than other more virulent Rickettsia strains, indicating a low pathogenicity of the current strain. Conclusions. Human infection with R. raoultii has a wide clinical spectrum that ranged from subclinical infection to severe complications. Physicians need to be aware of the high potential and clinical complexity of R.raoultii infection, to ensure appropriate testing and treatment in endemic regions. [ABSTRACT FROM AUTHOR]

Background: Human infection with Candidatus Rickettsia tarasevichiae (CRT) was first reported in northeastern China in 2012.Objective: To describe the clinical spectrum and laboratory findings of patients infected with CRT in eastern central China.Design: Case series.Setting: A sentinel hospital for severe fever with thrombocytopenia syndrome (SFTS) in eastern central China in 2014.Participants: Hospitalized patients with SFTS-like illness.Measurements: Molecular and serologic tests were performed to diagnose CRT infection. Data about clinical manifestations and laboratory findings were retrieved from medical records.Results: 56 of 733 assessed patients had CRT based on polymerase chain reaction and sequencing. All patients presented with nonspecific manifestations, including fever (96%), malaise (88%), myalgia (57%), cough (25%), and dizziness (14%). Only 2 patients had rash. Further, 16% had eschar, 29% had lymphadenopathy, 100% had gastrointestinal symptoms, 34% had neurologic symptoms, 43% had hemorrhagic manifestations, and 23% had signs of plasma leakage. Thrombocytopenia was observed in 70%, leukopenia in 59%; lymphopenia in 45%; and elevated levels of lactate dehydrogenase in 82%, aspartate aminotransferase in 70%, alanine aminotransferase in 54%, and creatinine kinase in 46%. Co-infection with SFTS virus was documented in 66% patients, and 8 of the 56 patients died.Limitations: Patients with CRT were not treated for infection because they were retrospectively identified. This was not a population-based study, and the results cannot be generalized to all patients with CRT.Conclusion: Candidatus R tarasevichiae infection should be considered in the differential diagnosis of febrile patients with SFTS-like illness in endemic areas.Primary Funding Source: National Natural Science Foundation of China. [ABSTRACT FROM AUTHOR]

Background: Rickettsia spp. belonging to the spotted fever group (SFG) cause infections in humans, domestic animals and wildlife. At least five SFG rickettsial species have been reported in China, but the occurrence of Rickettsia aeschlimannii and R. massiliae in ticks has not been characterized to date. Findings: A total of 114 adult ticks were collected from sheep in Yining County, Xinjiang Uygur Autonomous Region, in northwest China. The ticks were identified from morphological and molecular characteristics. All samples were examined by polymerase chain reaction (PCR), and six genetic markers were used to determine the Rickettsia spp. in the ticks. The ticks collected were identified as Rhipicephalus turanicus. Three different lineages of Rh. turanicus from Yining County were discovered on phylogenetic analysis of 16S rDNA and cox1. Twenty-one of the 114 samples (18.42%) were positive for rickettsial agents. Phylogenetic analysis based on six genetic sequences showed that three rickettsial species were present, namely: R. aeschlimannii (19.05%, 4/21), R. massiliae (19.05%, 4/21) and R. sibirica variant (61.90%, 13/21), which is clustered in the clade of R. sibirica subsp. sibirica. Conclusions: This is the first description of R. aeschlimannii and R. massiliae in China. R. massiliae, R. aeschlimannii and R. sibirica variant co-circulate in the region of the China-Kazakhstan border, in northwest China. Rickettsial agents in ticks of the genus Rhipicephalus from migrant birds, transported livestock, wildlife and human beings should be investigated further in the region of the China-Central Asian border. [ABSTRACT FROM AUTHOR]