Genetic structure and Rickettsia infection rates in Ixodes ovatus and Haemaphysalis flava ticks across different altitudes.

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.

Knowledge, attitudes, and practices regarding tick-borne diseases among an at-risk population living in Niigata prefecture, Japan.

OBJECTIVE: This study examined the knowledge, attitudes, and practices (KAP) of an at-risk population living in Niigata prefecture regarding tick-borne diseases (TBDs) and preventive strategies. METHODS: A cross-sectional questionnaire-based study was conducted to assess the KAP of the community. RESULTS: In total, 186 responses were received. Among the respondents, 130 (69·9%) were men, and the mean age was 51.1 (14·3). Nine (4·8%) respondents reported having experienced tick bites. Of the respondents, 44 (23.7%) knew about both scrub typhus and severe fever with thrombocytopenia syndrome, while 156 (83·9%) and 71 (38·2%) recognized limiting skin exposure and use of insect repellents as preventive measures, respectively. The attitudes towards TBDs: being worried about tick bites (p = 0·018) and interested in preventing TBDs (p = 0·001), were significantly higher among women than men. About 75% of the respondents reported taking preventive measures against tick bites, and limiting skin exposure was the most frequently applied method (69·9%). Insect repellents were used by 58 (31·2%) respondents. Age (p = 0·049), being worried about tick bites (p = 0·046), and knowledge of ticks score (p = 0·024) were the significant independent predictors of practicing countermeasures. CONCLUSION: We identified gaps in knowledge and practices regarding TBDs. Public health interventions should be implemented to improve public awareness of TBDs.

Comparative population genetic structure of two ixodid tick species (Acari:Ixodidae) (Ixodes ovatus and Haemaphysalis flava) in Niigata prefecture, Japan.

Ixodid ticks (Acari:Ixodidae) are essential vectors of tick-borne diseases in Japan. In this study, we characterized the population genetic structure and inferred genetic divergence in two widespread and abundant ixodid species, Ixodes ovatus and Haemaphysalis flava. Our hypothesis was that genetic divergence would be high in I. ovatus because of the low mobility of their small rodent hosts of immature I. ovatus would limit their gene flow compared to more mobile avian hosts of immature H. flava. We collected 320 adult I. ovatus from 29 locations and 223 adult H. flava from 17 locations across Niigata Prefecture, Japan, and investigated their genetic structure using DNA sequences from fragments of two mitochondrial gene regions, cox1 and the 16S rRNA gene. For I. ovatus, pairwise FST and analysis of molecular variance (AMOVA) analyses of cox1 and 16S sequences indicated significant genetic variation among populations, whereas both markers showed non-significant genetic variation among locations for H. flava. A cox1 gene tree and haplotype network revealed three genetic groups of I. ovatus. One of these groups consisted of haplotypes distributed at lower altitudes (251-471 m.a.s.l.). The cox1 sequences of I. ovatus from Japan clustered separately from I. ovatus sequences reported from China, suggesting the potential for cryptic species in Japan. Our results support our hypothesis and suggest that the host preference of ticks at the immature stage may influence the genetic structure of the ticks. This information may be important for understanding the tick-host interactions in the field to better understand the tick-borne disease transmission and in designing an effective tick control program.

Diversity and distribution of ticks in Niigata prefecture, Japan (2016-2018): Changes since 1950.

We performed tick surveys in all regions (Kaetsu, Chuetsu, Joetsu, and Sado) of the Niigata prefecture, Japan. A total of 105 field surveys were done from 2016 to 2018 in 41 sites, from north to south, in the prefecture. All 4806 ticks collected were identified and classified by species, sex, and developmental stage. Twelve species were recorded: Dermacentor taiwanensis, Haemaphysalis flava, Haemaphysalis hystricis, Haemaphysalis japonica, Haemaphysalis longicornis, Haemaphysalis megaspinosa, Ixodes ovatus, Ixodes nipponensis, Ixodes persulcatus, Ixodes monospinosus, Ixodes columnae, and Ixodes turdus. The major tick species in Niigata prefecture were H. flava, H. longicornis, and I. ovatus and they comprised 93.4% of all samples. These three species have one generation per year. Climatic and anthropogenic factors may be involved in the substantial change of the endemic species composition from a previous tick survey (1959) in the Niigata prefecture. These factors include increasing temperatures, introduction of new hosts such as the wild boar, highway construction, and a rural exodus facilitating animal migration and reproduction. Tick hosts suitable for the transmission of Japanese spotted fever, Lyme borreliosis, and SFTS occur in Niigata prefecture. Heightened awareness of these three tick-borne diseases is needed for preparation and disease prevention.

Spotted fever group rickettsiae (SFGR) detection in ticks following reported human case of Japanese spotted fever in Niigata Prefecture, Japan.

Japanese spotted fever, a tick-borne disease caused by Rickettsia japonica, was firstly described in southwestern Japan. There was a suspicion of Rickettsia japonica infected ticks reaching the non-endemic Niigata Prefecture after a confirmed case of Japanese spotted fever in July 2014. Therefore, from 2015 to 2017, 38 sites were surveyed and rickettsial pathogens were investigated in ticks from north to south of Niigata Prefecture including Sado island. A total of 3336 ticks were collected and identified revealing ticks of three genera and ten species: Dermacentor taiwanensis, Haemaphysalis flava, Haemaphysalis hystricis, Haemaphysalis longicornis, Haemaphysalis megaspinosa, Ixodes columnae, Ixodes monospinosus, Ixodes nipponensis, Ixodes ovatus, and Ixodes persulcatus. Investigation of rickettsial DNA showed no ticks infected by R. japonica. However, three species of spotted fever group rickettsiae (SFGR) were found in ticks, R. asiatica, R. helvetica, and R. monacensis, confirming Niigata Prefecture as a new endemic area to SFGR. These results highlight the need for public awareness of the occurrence of this tick-borne disease, which necessitates the establishment of public health initiatives to mitigate its spread.

Scrub typhus caused by Shimokoshi type Orientia tsutsugamushi showing variant 56-kDa type-specific antigen gene sequence in Tohoku region, Japan.

In 2018, a patient was diagnosed with Shimokoshi type scrub typhus in Yamagata Prefecture, Japan. The causative pathogen was likely a variant type because 43 (8.3%) of 521 deduced amino acid sequences of the 56-kDa type-specific antigen (TSA) were different from those of the Shimokoshi prototype strain. The patient's paired sera showed low antibody titers against the Shimokoshi prototype strain. Two cases of scrub typhus reported in the Tohoku region during 2011-2012 also involved the same 56-kDa TSA gene sequence. These findings suggest the presence of diversity in Shimokoshi type Orientia tsutsugamushi, which may impede the laboratory diagnosis of scrub typhus.

Cognitive and brain reserve in conversion and reversion in patients with mild cognitive impairment over 12 months of follow-up.

INTRODUCTION: Two reserve hypotheses have been proposed to account for the observed disjunction between the degree of brain pathology and its clinical manifestations. This study investigated whether cognitive reserve (CR), taken here as educational attainment and premorbid IQ, or brain reserve (BR; i.e., brain volume) is associated with progression and regression in patients with mild cognitive impairment (MCI) over a 12-month follow-up. METHOD: Patients with MCI (n = 123) were prospectively enrolled. The Mini-Mental State Examination, the Japanese version of the Cognitive subscale of the Alzheimer's Disease Assessment Scale, the Clinical Dementia Rating (CDR), the Frontal Assessment Battery, the Neuropsychiatric Inventory, magnetic resonance imaging (MRI), and quantitative single-photon emission computed tomography were performed at intake and again at 12-month follow-up. Patients were classified into three groups: no change, conversion, and reversion. Conversion was defined as a change in CDR from 0.5 to 1, and reversion as a change from 0.5 to 0. RESULTS: Voxel-based morphometry MRI revealed no significant differences in entorhinal and hippocampal gray matter loss among the groups. Patients with reversion had higher premorbid IQ (p = .03, ηp(2) = .35) as measured by the Japanese version of the National Adult Reading Test, higher atrophy ratio (hippocampal volume/whole brain volume; p = .04, ηp(2) = .89) at baseline, and better cognitive performance (p < .001) during the 12-month follow-up than those with conversion did. There were no statistically significant differences among the three groups in terms of years of education. CONCLUSION: Multinomial logistic regression analysis revealed that higher CR contributed to protecting against cognitive decline during the 12-month follow-up, whereas higher BR at baseline was the strongest predictor for reversion and conversion.

Impact of lifestyle-related disease on conversion and reversion in patients with mild cognitive impairment: after 12 months of follow-up.

OBJECTIVE: The objective of the study is to investigate whether the lifestyle-related disease (LSRD) hypertension, type II diabetes mellitus, and lipid abnormality are associated with conversion and reversion in patients with mild cognitive impairment (MCI) over 12 months of follow-up. METHODS: One hundred and thirteen patients with MCI were prospectively enrolled and longitudinally assessed. Methods used include mini-mental state examination, the Japanese version of the cognitive subscale of the Alzheimer's Disease Assessment Scale, the Clinical Dementia Rating, the Frontal Assessment Battery, the Neuropsychiatric Inventory, magnetic resonance imaging, and quantitative single-photon emission computed tomography. In addition, laboratory examinations of glucose and lipids were also performed. All measurements were performed at first intake and again at the end of the 12-month follow-up. Conversion was identified as a change in Clinical Dementia Rating from 0.5 to 1 and reversion as a change from 0.5 to 0. RESULTS: Patients with MCI with reversion had lower comorbid lipid abnormality at baseline and higher cognitive and behaviour function across the 12-month follow-up compared with those with no change or conversion. Patients without comorbid LSRD had lower systolic pressure and lower glucose and triglyceride levels at baseline, as well as less cognitive decline compared with other groups across the follow-up period. CONCLUSIONS: The absence of lipid abnormality at baseline may contribute to reversion in patients with MCI. The presence of multiple LSRD was associated with cognitive decline. Our results highlight the contribution of multiple LSRD on increasing conversion and decreasing reversion in patients with MCI. Copyright © 2015 John Wiley & Sons, Ltd.

Impact of cognitive reserve on the progression of mild cognitive impairment to Alzheimer's disease in Japan.

AIM: The present study aimed to investigate whether cognitive reserve (CR), referring here to education and premorbid intelligence (IQ), is associated with the risk for progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD). METHODS: A total of 51 patients with MCI and 59 patients with AD were prospectively enrolled for assessment with the Mini-Mental State Examination, the Japanese version of the cognitive subscale of the Alzheimer's Disease Assessment Scale, the Japanese version of the Nelson Adult Reading Test (JART), magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT), adjusting for sex, age at diagnosis, age at onset and duration of illness. RESULTS: SPECT findings showed hypoperfusion in the posterior cingulate gyri and precunei, suggesting that the participants were in the early or mild stage of AD or MCI. Voxel-based morphometry MRI showed no statistical differences between the two groups in gray matter loss in the entorhinal and hippocampal areas; however, multiple logistic regression analysis showed a significant difference in premorbid IQ measured with JART. CONCLUSION: Despite the limitations of the cross-sectional design, the findings suggest that premorbid intellectual function might explain the discrepancy in clinical status between MCI and AD patients with a similar magnitude of brain pathology and comorbid medical disorders.

Phylogenetic Clades 6 and 8 of Enterohemorrhagic Escherichia coli O157:H7 With Particular stx Subtypes are More Frequently Found in Isolates From Hemolytic Uremic Syndrome Patients Than From Asymptomatic Carriers.

BACKGROUND: Enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection causes severe diseases such as bloody diarrhea and hemolytic uremic syndrome (HUS). Although EHEC O157:H7 strains have exhibited high genetic variability, their abilities to cause human diseases have not been fully examined. METHODS: Clade typing and stx subtyping of EHEC O157:H7 strains, which were isolated in Japan during 1999-2011 from 269 HUS patients and 387 asymptomatic carriers (ACs) and showed distinct pulsed-field gel electrophoresis patterns, were performed to determine relationships between specific lineages and clinical presentation. RESULTS: Clades 6 and 8 strains were more frequently found among the isolates from HUS cases than those from ACs (P = .00062 for clade 6, P < .0001 for clade 8). All clade 6 strains isolated from HUS patients harbored stx2a and/or stx2c, whereas all clade 8 strains harbored either stx2a or stx2a/stx2c. However, clade 7 strains were predominantly found among the AC isolates but less frequently found among the HUS isolates, suggesting a significant association between clade 7 and AC (P < .0001). Logistic regression analysis revealed that 0-9 year old age is a significant predictor of the association between clade 8 and HUS. We also found an intact norV gene, which encodes for a nitric oxide reductase that inhibits Shiga toxin activity under anaerobic condition, in all clades 1-3 isolates but not in clades 4-8 isolates. CONCLUSIONS: Early detection of EHEC O157:H7 strains that belonged to clades 6/8 and harbored specific stx subtypes may be important for defining the risk of disease progression in EHEC-infected 0- to 9-year-old children.

Executive dysfunction in remitted late-life depression: Juntendo University Mood Disorder Projects (JUMP).

The authors aimed to investigate whether remitted adult and elderly major depressive disorder patients show different patterns of executive dysfunction. Executive functions of 20 euthymic major depressive disorder patients and 29 healthy comparison subjects were evaluated using the Behavioral Assessment of the Dysexecutive Syndrome. Relative to adult patients and healthy comparison subjects, euthymic elderly patients were more impaired in the subtest of Modified Six Elements. Since the regions most implicated in this subtest are the medial prefrontal, the anterior cingulate, and the dorsolateral prefrontal areas, the authors conclude that dysfunctions of such frontal neural networks remain unresolved even in the remission phase of late-life depression.