Authors: Xiang-Rong Qin, Hui-Ju Han, Fu-Jun Han...

PCR amplification indicated the minimum infection rate of Rickettsia spp. was 0.66% in Haemaphysalis longicornis ticks collected from Shandong Province, China. Phylogenetic analysis based on the rrs, gltA, ompA, and ompB genes indicated that the ticks carried R. japonica, Candidatus Rickettsia longicornii, and a novel Rickettsia species related to R. canadensis.

Topics: Animals; China; DNA, Bacterial; Humans; Phylogeny; Polymerase Chain Reaction; Public Health Surveillance; Rickettsia; Ticks; Vector Borne Diseases

PubMed: 31002060
DOI: 10.3201/eid2505.171745

Authors: Hisashi Inokuma, Hironori Matsuda, Leo Sakamoto...

Rickettsia japonica pathogenesis and reservoir potential in dogs were evaluated by both experimental inoculation and epidemiologic survey. In the experimental inoculation study, dogs 1 and 2 were pretreated with an immunosuppressive dose of cyclosporine 14 days before inoculation and became ill after exposure to R. japonica. Dogs exhibited clinical signs, including fever, anorexia, depression, and decreased water consumption, between 36 and 96 h after inoculation, but these signs disappeared spontaneously by 5 days after inoculation. Dogs 3 and 4 were not pretreated with cyclosporine, and no clinical signs were detected in them throughout the 14-day observation period. The control dog was clinically normal and had a normal rectal temperature throughout the study period. We attempted to detect rickettsial DNA from peripheral blood and aspiration samples from kidney and spleen by nested PCR, but all samples examined were negative. The control dog lacked detectable titers to R. japonica antigen on day 14, while positive antibodies to R. japonica were detected in all four experimentally infected dogs, with titers of 1:160 to 1:80. In the epidemiologic survey, 24 (1.8%) of the 1,363 dogs examined throughout Japan had antibodies against R. japonica, with titers of 1:40 or more. However, we observed neither clinical signs at the time of sample collection nor nested PCR results indicative of rickettsial infection in these dogs. In conclusion, dogs in Japan can be exposed to R. japonica, and infected dogs with immunosuppressive conditions can temporarily develop clinical symptoms, including fever, anorexia, depression, and decreased water consumption.

Topics: Animals; Antibodies, Bacterial; DNA, Bacterial; Disease Reservoirs; Dog Diseases; Dogs; Japan; Rickettsia; Rickettsia Infections

PubMed: 20980481
DOI: 10.1128/CVI.00369-10

Authors: Kentaro Kasama, Hiromi Fujita, Seigo Yamamoto...

is the causative agent of Far-Eastern spotted fever (FESF). In Japan, a human case of FESF was identified in Sendai in Miyagi Prefecture in 2008, and bacteria were isolated from ticks collected in the suspected geographical area of infection. Although the intraspecies genome diversity of Rickettsia has been poorly investigated, our recent analysis revealed extremely low genomic diversity of , the agent of Japanese spotted fever, which is a close relative of . In this study, to investigate the genomic diversity of and understand the genetic relationship between Japanese and Chinese isolates, we sequenced three isolates from ticks collected in Sendai and one isolate from a tick collected in Inner Mongolia, China, and performed genomic comparisons between these isolates and strain 054, the type strain isolated from a tick in Heilongjiang Province, China. Although the three Japanese strains were isolated in 2008, 2009, and 2012, their genome sequences were identical, indicating that ticks carrying a single clone have been distributed in Sendai, Japan. Among the five isolates, only 81 SNPs and 13 insertion/deletion sites were identified, despite the significant differences in these isolates both geographically and temporally. A significant portion of the 81 SNPs (16/81) were found to be recombinogenic. These results indicate low genomic diversity of , as observed in . We further performed a detailed genomic comparison of and to accurately define conserved and species-specific genes. This analysis revealed that although notable variations were found in the genomic loci encoding RelA/SpoT family proteins and tandem repeats in major surface proteins, there was only a small difference in the gene repertoire between the two species, suggesting that SNPs and small InDels are responsible for the functional or physiological differences between the two species, if present. Through this analysis, several species-specific genomic regions that can serve as ideal PCR targets for distinguishing and were also identified.

PubMed: 31866968
DOI: 10.3389/fmicb.2019.02787

Authors: Hao Li, Pan-He Zhang, Juan Du...

During 2014-2017, we screened for Rickettsia japonica infection in Xinyang, China, and identified 20 cases. The major clinical manifestations of monoinfection were fever, asthenia, myalgia, rash, and anorexia; laboratory findings included thrombocytopenia and elevated hepatic aminotransferase concentrations. Physicians in China should consider R. japonica infection in at-risk patients.

Topics: Adult; Aged; Animals; China; Female; Humans; Male; Middle Aged; Phylogeny; Rickettsia; Rickettsia Infections; Risk Factors; Tick Bites; Ticks

PubMed: 31441748
DOI: 10.3201/eid2509.171421

Authors: Tatsuya Fujikawa, Tomoki Yoshikawa, Takeshi Kurosu...

Severe fever with thrombocytopenia syndrome was diagnosed in a febrile woman in Japan after a tick bite. However, Rickettsia japonica DNA was retrospectively detected in the eschar specimen, suggesting co-infection from the bite. Establishment of the severe fever with thrombocytopenia syndrome virus infection might have overpowered the R. japonica infection.

Topics: Coinfection; Female; Humans; Japan; Retrospective Studies; Rickettsia; Rickettsia Infections; Severe Fever with Thrombocytopenia Syndrome; Tick Bites

PubMed: 33755004
DOI: 10.3201/eid2704.203610

Authors: Maria Angenica F Regilme, Megumi Sato, Tsutomu Tamura...

Ixodid ticks, such as Ixodes ovatus and Haemaphysalis flava, are important vectors of tick-borne diseases in Japan, such as Japanese spotted fever caused by Rickettsia japonica. This study describes the Rickettsia infection rates influenced by the population genetic structure of I.ovatus and H. flava along an altitudinal gradient. A total of 346 adult I. ovatus and 243 H. flava were analyzed for the presence of Rickettsia by nested PCR targeting the 17kDA, gltA, rOmpA, and rOmpB genes. The population genetic structure was analyzed utilizing the mitochondrial cytochrome oxidase 1 (cox1) marker. The Rickettsia infection rates were 13.26% in I. ovatus and 6.17% in H. flava. For I. ovatus, the global FST value revealed significant genetic differentiation among the different populations, whereas H. flava showed non-significant genetic differentiation. The cox1 I. ovatus cluster dendrogram showed two cluster groups, while the haplotype network and phylogenetic tree showed three genetic groups. A significant difference was observed in Rickettsia infection rates and mean altitude per group between the two cluster groups and the three genetic groups identified within I. ovatus. No significant differences were found in the mean altitude or Rickettsia infection rates of H. flava. Our results suggest a potential correlation between the low gene flow in I. ovatus populations and the spatially heterogeneous Rickettsia infection rates observed along the altitudinal gradient. This information can be used in understanding the relationship between the tick vector, its pathogen, and environmental factors, such as altitude, and for the control of tick-borne diseases in Japan.

Topics: Animals; Ixodes; Altitude; Phylogeny; Ixodidae; Rickettsia Infections; Rickettsia; Spotted Fever Group Rickettsiosis; Genetic Structures

PubMed: 38478554
DOI: 10.1371/journal.pone.0298656

Authors: Makoto Kondo, Yoshiaki Matsushima, Kento Mizutani...

(1) Background. () infection induces severe inflammation, and the disappearance of eosinophil in the acute stage is one of the phenomena. (2) Materials and Methods. In the current study, we measured the serum concentrations of Th1, Th2, and Th17 cytokines in the acute and recovery stages. (3) Results. In the acute phase, IL-6 and IFN-γ levels were elevated and we speculated that they played a role as a defense mechanism against . The high concentration of IFN-γ suppressed the differentiation of eosinophil and induced apoptosis of eosinophil, leading to the disappearance of eosinophil. On day 7, IL-6 and IFN-γ concentrations were decreased, and Th2 cytokines such as IL-5 and IL-9 were slightly increased. On day 14, eosinophil count recovered to the normal level. The transition of serum cytokine concentration in infection was presented. (4) Conclusions. IL-6 and IFN-γ seem to be critical cytokines as defense mechanism against in the acute phase, and this may deeply connect to the decrease of eosinophil.

PubMed: 33322277
DOI: 10.3390/idr12030023

Authors: Tetsuro Aita, Eiichiro Sando, Shungo Katoh...

To elucidate the epidemiology of murine typhus, which is infrequently reported in Japan, we conducted a cross-sectional study involving 2,382 residents of rickettsiosis-endemic areas in Honshu Island during August-November 2020. Rickettsia typhi seroprevalence rate was higher than that of Orientia tsutsugamushi, indicating that murine typhus is a neglected disease.

Topics: Animals; Mice; Humans; Typhus, Endemic Flea-Borne; Scrub Typhus; Seroepidemiologic Studies; Japan; Cross-Sectional Studies; Orientia tsutsugamushi; Rickettsia typhi

PubMed: 37347821
DOI: 10.3201/eid2907.230037

Authors: Xiaoxu Wang, Meng Shang, Zihao Wang...

OBJECTIVE

To determine the current and future suitable areas of , and to provide a reference for preventing its outbreak and spread.

METHODS

Based on the geographic distribution of and overlapping data points and information on 56 climatic factors, we utilized the Maxent model to estimate suitable areas for in Asian adjacent Regions and China. Model parameter adjustments and the construction of receiver operating characteristic curves were conducted using R 4.3.0 software.

RESULTS

Average precipitation in June (prec6, 28.2%), Temperature Seasonality (bio4, 9.8%) and the minimum temperature in August (tmin8, 9.2%) contributed most to the distribution of . The performance metrics for the Maxent model in predicting the distribution of are as follows: the Area Under the Curve (AUC) is 0.990, the True Skill Statistic (TSS) is 0.857, and the Kappa statistic is 0.763. Under current climatic conditions, the Asian and adjacent space medium and highly suitable areas for are estimated to be 176.78 × 10 km and 95.13 × 10 km, respectively. The highly suitable areas for were mainly distributed in east and south Asia. In China, the high suitability areas are mainly distributed in the southeast coastal areas and the Qinling Mountains and Huai River cities. Under future climatic conditions, the Asian and adjacent regions maximum area change rate of increased by 118.65%, and that of China increased by 50.42%. Meanwhile, the suitable areas of gradually expanding northward in China.

CONCLUSION

Under global climate change, the suitable area of is generally increasing, with a northward shift observed in China. Governments should strengthen monitoring, risk assessment, and response strategies in highly suitable regions, while also preventing the invasion of from external source.

Topics: Climate Change; China; Rickettsia; Humans; Animals; Rickettsia Infections

PubMed: 40115352
DOI: 10.3389/fpubh.2025.1478736

Authors: Fanfan Xing, Chaowen Deng, Jinyue Huang...

Rickettsiosis includes a diversity of culture-negative non-specific systemic infections. Laboratory diagnosis of rickettsiosis is often not easy. In this 12-month study, six patients with a variety of rickettsia infections of the spotted fever group, typhus group and scrub typhus were diagnosed directly or indirectly by metagenomic next-generation sequencing (mNGS). The patient with Japanese spotted fever was rapidly made when mNGS analysis of the patient's blood revealed Rickettsia japonica sequences. For the two patients with Rickettsia felis chest infections, the bacterium was detected in the bronchoalveolar lavage of one case and lung biopsy of the other. Both patients had underlying malignancies, carcinoma of the breast and carcinoma of the lung respectively, and were on chemotherapy with immunosuppressive effect. For the remaining three patients who presented over a period of 13 weeks, all had fever, headache and the typical eschar. They also had increased serum transaminases and responded promptly to doxycycline. However, the Weil-Felix test results of all three patients were negative. Since we considered the three cases typical of rickettsiosis, we submitted their serum samples for mNGS analysis. Results showed that Orientia tsutsugamushi sequences were present in the serum of one case. In view of the positive mNGS results, we repeated the Weil-Felix test for the residual sera of all three patients and it revealed that those of the other two cases showed OX-19 titers of 1:640 and 1:160 respectively, inferring that these two patients probably had rickettsiosis of the typhus group. As for the patient positive for O. tsutsugamushi sequences, we also detected IgM for O. tsutsugamushi in the serum, which double confirmed that it was a case of scrub typhus. mNGS is an important molecular tool and can complement serology for laboratory diagnosis of rickettsiosis.

Topics: Humans; Female; Male; Rickettsia Infections; High-Throughput Nucleotide Sequencing; Middle Aged; Rickettsia; Aged; Metagenomics; Adult; Orientia tsutsugamushi; Scrub Typhus; Molecular Diagnostic Techniques

PubMed: 39383151
DOI: 10.1371/journal.pntd.0012546