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Case Report: An imported severe case of paediatric scrub typhus with Karp B subgenotype in non-endemic Northern China, Beijing.

Scrub typhus, a zoonosis caused by Orientia tsutsugamushi (O. tsutsugamushi), remains a significant public health threat in the Asia-Pacific region. This disease is transmitted through the bite of infected trombiculid mite larvae (chiggers) and typically manifests as acute undifferentiated fever during the early stage. Despite the availability of targeted antibiotic therapies, delayed diagnosis frequently leads to severe complications and fatal outcomes. Here, we report a severe imported paediatric case in Beijing, a city in China's temperate zone, involving a 12-year-old girl with a recent tr…

Determination of Optimal Diagnostic Cut-Offs for the Naval Medical Research Center Scrub Typhus IgM ELISA in Chiang Rai, Thailand.

In this diagnostic accuracy study, we evaluated data from 135 febrile patients from Chiang Rai, to determine the optimal optical density (OD) cutoffs for an in-house scrub typhus IgM ELISA. Receiver operating characteristic curves were generated using a panel of reference assays, including an IgM immunofluorescence assay (IFA), PCR, in vitro isolation, presence of an eschar, or a combination of these. Altogether, 33 patients (24.4%) were diagnosed as having scrub typhus. Correlation between positivity by IFA and increasing OD values peaked at a cutoff of 2.0, whereas there was little associati…

Clinical profile and risk factors associated with severe scrub typhus infection among non-ICU patients in semi-urban south India.

BACKGROUND & OBJECTIVES: Scrub typhus is as an emerging infectious disease that generally causes acute febrile illness, with disease spectrum ranging from mild illness to multiorgan dysfunction. This study was aimed to report the clinical profile, complications and risk factors associated with severe illness in patients with scrub typhus, outside the intensive care setting. METHODS: It was a prospective study, which involved recruitment of patients with acute febrile illness and diagnosed to have scrub typhus, who were admitted to the general medical wards of a tertiary care centre in Kanchip…

Validation of Geno-Sen's Scrub Typhus Real Time Polymerase Chain Reaction Kit by its Comparison with a Serological ELISA Test.

BACKGROUND: In the recent past, scrub typhus (ST) has been reported from different parts of India, based on Weil-Felix/enzyme-linked immunosorbent assay (ELISA)/indirect immunofluorescence assay (IFA). Molecular tests are applied only by a few researchers. AIMS: Evaluation of a new commercial real time polymerase chain reaction (PCR) kit for molecular diagnosis of ST by comparing it with the commonly used IgM ELISA is our aim. SETTINGS AND DESIGN: ST has been reported all over India including Puducherry and surrounding Tamil Nadu and identified as endemic for ST. This study was designed to c…

Orientia tsutsugamushi, agent of scrub typhus, displays a single metapopulation with maintenance of ancestral haplotypes throughout continental South East Asia.

Orientia tsutsugamushi is the causative agent of scrub typhus, a major cause of febrile illness in rural area of Asia-Pacific region. A multi-locus sequence typing (MLST) analysis was performed on strains isolated from human patients from 3 countries in Southeast Asia: Cambodia, Vietnam and Thailand. The phylogeny of the 56-kDa protein encoding gene was analyzed on the same strains and showed a structured topology with genetically distinct clusters. MLST analysis did not lead to the same conclusion. DNA polymorphism and phylogeny of individual gene loci indicated a significant level of recombi…

[Sequence analysis subtyping of the 56-kDa protein-encoding gene of Karp-type Orientia tsutsugamushi isolated in scrub typhus cases].

To determine the Karp-type Orientia tsutsugamushi subtype in northern Japan, i.e., Yamagata, Niigata, and Akita Prefectures, we analyzed the partial nucleotide sequence of the 56-kDa protein-encoding gene of 30 isolates from scrub typhus cases. Based on sequencing results, we classified isolates into two groups of 27 and 3 isolates. Nucleotide sequences of 27 isolates were homologous to the yeo-joo strain, classified as a JP-1 subtype. The three isolates were each homologous to a stain of CMM1, KNP1, or KNP2, classified as JP-2 subtypes. Phylogenetic tree analysis showed the 27 isolates formin…

Atypical Clinical Manifestations and Laboratory Predictors of Severe Scrub Typhus in Hospitalized Adults at Two Tertiary Care Hospitals in North India.

INTRODUCTION: Scrub typhus is a re-emerging, neglected tropical disease in India, often presenting with nonspecific symptoms. While classical features are well-documented, atypical and severe manifestations are underreported and frequently misdiagnosed. OBJECTIVES: Our objective was to describe uncommon clinical manifestations of scrub typhus in hospitalized patients at two tertiary care hospitals in Northern India. METHODS: This prospective cross-sectional study included 22 adult patients (no controls) with serologically confirmed scrub typhus (IgM ELISA positive) presenting between January…

Mathematical analysis of scrub typhus seasonal infection with re-scaled transmission rate considering Northeast India reported data from 2010 to 2022.

Healthcare reporting methods have seen a common problem with actual incidence of scrub typhus cases in Northeast India that were reported during post rainy season. We propose a Host-Vector model, a first of its kind, with a significant modification in the disease infection transmission rate. Our work aims to investigate a mathematical model by Atangana-Baleanu fractal-fractional operator that has seasonal pattern incorporating 2010-2022 data. The existence-uniqueness property is investigated using the fixed point theory, and also Ulam-Hyers stability is performed. Based on Lagrange's interpola…

A whole blood intracellular cytokine assay optimised for field site studies demonstrates polyfunctionality of CD4+ T cells in acute scrub typhus.

BACKGROUND: Assessment of cellular immune responses by combining intracellular cytokine staining and immunophenotyping using flow cytometry … monstrate the ability of the WBA to capture polyfunctional T cell responses in the context of acute scrub typhus infection, by measuring IFN-γ, TNF and IL-2 in CD4+ and CD8+ T cells in response to the causative agent O. tsutsugamushi (OT). Using an optimised OT antigen preparation, we demonstrate the presence of polyfunctional antigen-specific memory CD4+ T ce …

Simple clinical and laboratory predictors to improve empirical treatment strategies in areas of high scrub typhus and dengue endemicity, central Vietnam.

BACKGROUND: Dengue fever is highly endemic in Vietnam, but scrub typhus-although recognized as an endemic disease-remains underappreciated. These diseases together are likely to account for more than half of the acute undifferentiated fever burden in Vietnam. Scrub typhus (ST) is a bacterial disease requiring antimicrobial treatment, while dengue fever (DF) is of viral etiology and does not. The access to adequate diagnostics and the current understanding of empirical treatment strategies for both illnesses remain limited. In this study we aimed to contribute to the clinical decision process i…

Временная связь между метеорологическими факторами и скребным тифом с дистрибутивной нелинейной моделью в сельской юго-западной части Китая.

СПРАВОЧНАЯ ИНФОРМАЦИЯ: Метеорологические факторы могут влиять на появление скруба тифа в течение периода продолжительностью от нескольких дней до недель после их возникновения. Кроме того, связь между метеорологическими факторами и скруб-тифом является сложной из-за отставших и нелинейных моделей. Изучение отстающих структур корреляции между метеорологическими переменными и скруб-тифами может способствовать пониманию этой связи и способствовать предотвращению вспышек заболеваний. Мы извлекали данные о случаях скруба тифа в сельских районах Панжихуа в юго-западном Китае каждую неделю с 2008 по

Совпадение в аннотации оригинала
BACKGROUND: Meteorological factors can affect the emergence of scrub typhus for a period lasting days to weeks after their occurrence. Furthermore, the relationship between meteorological factors and scrub typhus is complicated because of lagged and non-linear patterns. Investigating the lagged correlation patterns between meteorological variables and scrub …

Early diagnosis of scrub typhus with a rapid flow assay using recombinant major outer membrane protein antigen (r56) of Orientia tsutsugamushi.

The variable 56-kDa major outer membrane protein of Orientia tsutsugamushi is the immunodominant antigen in human scrub typhus infections. We developed a rapid immunochromatographic flow assay (RFA) for the detection of immunoglobulin M (IgM) and IgG antibodies to O. tsutsugamushi. The RFA employs a truncated recombinant 56-kDa protein from the Karp strain as the antigen. The performance of the RFA was evaluated with a panel of 321 sera (serial bleedings of 85 individuals suspected of scrub typhus) which were collected in the Pescadore Islands, Taiwan, from 1976 to 1977. Among these 85 individ…

Non-linear effects and lag patterns of eco-environmental factors on scrub typhus: a spatiotemporal analysis in Yunnan, China, 2015-2022.

BACKGROUND: Yunnan Province is characterized by a high incidence of scrub typhus and complex ecological environments, where epidemic patterns are shaped by the dual influence of the plateau monsoon system and geomorphological evolution. However, macro-scale meteorological indicators often fail to accurately capture climatic features within such rugged terrains, leaving the multi-factor coupled spatiotemporal associations of scrub typhus epidemics elusive. METHODS: This study integrates Wavelet periodicity analysis and STL decomposition to identify the temporal rhythms and structural mutations…

Associations between meteorological factors and scrub typhus incidence: a systematic review and meta-analysis of linear and nonlinear dose-response relationships.

BACKGROUND: Scrub typhus is an important zoonotic disease with rising incidence globally. Meteorological factors may influence its transmission dynamics. However, inconsistencies across studies and limited quantitative evidence highlight the need for further investigation. OBJECTIVE: To systematically evaluate the linear and nonlinear associations between various meteorological factors and scrub typhus incidence, explore lagged effects and potential sources of heterogeneity, and analyze inconsistencies in existing findings. METHOD: We searched PubMed, Scopus, Web of Science, and Embase for s…

Molecular detection of Orientia tsutsugamushi in ectoparasites & their small mammal hosts captured from scrub typhus endemic areas in Madurai district, India.

BACKGROUND OBJECTIVES: Scrub typhus, caused by Orientia tsutsugamushi present in small mammals harbouring the ectoparasites. A study was undertaken to detect the pathogen present in small mammals and its ectoparasites in the scrub typhus-reported areas. METHODS: The small mammals (rodents/shrews) and its ectoparasites were screened for O. tsutsugamushi using nested PCR amplification of the groEL gene. Small mammals were collected by trapping and screened for ectoparasites (mites, ticks and fleas) by combing method. RESULTS: All the chigger mites collected were tested negative for O. tsutsuga…

[Knowledge, attitudes and practices towards scrub typhus control and associated influencing factors among residents in Longling County, Yunnan Province in 2023].

OBJECTIVE: To investigate the knowledge, attitudes and practices (KAP) towards scrub typhus control and analyse the influencing factors among residents in Longling County, Yunnan Province in 2023, so as to provide insights into management of scrub typhus in the county. METHODS: Two townships were randomly sampled from Longling County, Baoshan City, Yunnan Province in July 2023, and 2 to 3 administrative villages were randomly selected from each township. Then, 20 to 40 households were randomly selected from each village, and 1 to 2 villagers were surveyed in each household. Residents' KAP tow…

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 ts…