Background A tick-borne segmented RNA virus called Jingmen tick virus (JMTV) was recently identified, variants of which were detected in a non-human primate host and fatal patients with Crimean-Congo haemorrhagic fever. We investigated its infectivity and pathogenicity for humans. Methods We obtained skin-biopsy, blood and serum samples from patients with tick bites, and used high-throughput sequencing, in situ hybridisation, and serologic testing to diagnose and ascertain the cases of JMTV infection. Findings A JMTV strain was isolated from the tick Amblyomma javanense into an embryo-derived tick cell line. We obtained sustained passage of JMTV, and revealed that it was able to accumulate in salivary glands of experimentally infected ticks. Four JMTV-infected patients were identified by high-throughput sequencing of skin biopsies and blood samples. The virus replication in skin tissue was visualised by in situ hybridisation. The four patients all had an itchy or painful eschar at the site of tick bite, with or without lymphadenopathy. Immunohistochemical examination revealed remarkable local inflammation manifested as infiltration by neutrophils. Eight patients were identified by serological testing and showed more severe clinical manifestations. Two Ixodes persulcatus ticks detached from patients were positive for JMTV. All JMTV strains identified in this study formed a well-supported sub-lineage, distinct from those previously reported in China. Interpretation The public significance of JMTV should be highly concerning due to its potential pathogenicity for humans and efficient transmission by potential ticks. Fund China Natural Science Foundation, State Key Research Development Programme, and United Kingdom Biotechnology and Biological Sciences Research Council.

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To identify Candidatus Neoehrlichia mikurensis infection in northeastern China, we tested blood samples from 622 febrile patients. We identified in 7 infected patients and natural foci for this bacterium. Field surveys showed that 1.6% of ticks and 3.8% of rodents collected from residences of patients were also infected.

We used molecular methods to identify Rickettsia raoultii infections in 2 persons in China. These persons had localized rashes around sites of tick bites. R. raoultii DNA was detected in 4% of Dermacentor silvarum ticks collected in the same area of China and in 1 feeding tick detached from 1 patient.

We conducted an investigation of Borrelia miyamotoi infections in humans and ticks in northeastern China. Of 984 patients reporting recent tick bites, 14 (1.4%) were found to be infected with B. miyamotoi by PCR and genomic sequencing. The 14 patients had nonspecific febrile manifestations, including fever, headache, anorexia, asthenia, and arthralgia. Rash, eschar, and regional lymphadenopathy were each observed in 1 patient. Four (28.6%) patients were hospitalized because of severe disease. B. miyamotoi was detected in 3.0% (19/627) of Ixodes persulcatus, 1 (2.8%) of 36 Haemaphysalis concinna, and none of 29 Dermacentor silvarum ticks. Phylogenetic analyses based on sequences of a nearly entire 16s rRNA gene, a partial flagellin gene, and the glycerophosphodiester phosphodiesterase gene revealed that B. miyamotoi identified in patients and ticks were clustered in the group of the Siberian type. These findings indicate that B. miyamotoi is endemic in northeastern China and its public health significance deserves further investigation.

We identified B. crassa-like infection in people in northeastern China that caused mild to moderate symptoms. The possibility of more severe disease in immunocompromised patients and of transmission through the blood supply due to asymptomatic infections justifies further investigation of this reported infection.

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The variety of Borrelia burgdorferi sensu lato (B. burgdorferi) genospecies leads to distinction in clinical manifestations of Lyme borreliosis (LB). There are reports of LB clinical characteristics in China, where the B. burgdorferi genospecies in ticks and animal hosts are different from those in Europe and North America. During May to September in 2010 and 2011, all patients who had erythema migrans (EM, more than 5 cm in diameter) after a recent tick-bite, and sought medical care at Mudanjiang Forestry Central Hospital, Heilongjiang Province of northeastern China, were enrolled in the study. Specific PCR was used to determine the B. burgdorferi genospecies in the disseminated patients. Of 265 EM patients, B. burgdorferi DNA was detected in blood specimens from 15 of 55 disseminated patients. Sequence analyses of 5S-23S rRNA, flagellin, ospC, 16S rRNA and ospA genes revealed that 11 patients were infected with Borrelia garinii, three with Borrelia afzelii and one with Borrelia valaisiana-related genospecies. Among 15 patients, 40%, 13.3% and 13.3% manifested pruritus, pain and ulceration, respectively. Systemic symptoms, arthralgia or a swollen joint and lymphadenopathy were observed in 26.7%, 13.3% and 6.7% patients, respectively. In northeastern China, three genospecies of LB patients were detected. The B. burgdorferi genospecies identified in this study was predominantly B. garinii. A case infected with B. valaisiana-related genospecies was reported for the first time.