Myositis and rhabdomyolysis in scrub typhus infection: A case report

Rationale:Fever with myositis and rhabdomyolysis is a medical emergency requiring prompt diagnosis and management.Scrub typhus associated myositis with rhabdomyolysis is rare.Patient concerns:A 36-year-old female presented with intermittent fever up to 38.6℃,jaundice and progressive weakness of all four limbs.Diagnosis:Scrub typhus associated myositis and rhabdomyolysis.Intervention:Doxycycline 100 mg twice daily and injection of ceftriaxone 1 gm twice daily along with continuous intravenous fluids.Outcome:Fever resolved with normalization of liver function and recovery of muscle power.Lessons:Presence of myositis and rhabdomyolysis is uncommon in scrub typhus;high clinical suspicion should be kept in patients with atypical manifestations of scrub typhus.

Epidemiology and clinico-laboratory manifestations of scrub typhus in Hadoti region of Rajasthan,India:A cross-sectional study

Objective:To study epidemiology,clinical manifestations,and laboratory parameters of scrub typhus in Hadoti region of Rajasthan,India.Methods:A cross-sectional study was conducted on 50 patients with scrub typhus between August 2022 and November 2022.Scrub typhus was diagnosed by ELISA IgM scrub typhus antibody.The data about demography,vital parameters,and lab investigations were collected and analyzed.Results:Ninety-two percent of the patients were from a rural background(92%),86% were farmers and the majority were females.Most patients were 40-60 years old.The major complaints were fever(100%),myalgia(100%),headache(82%),and body swelling(80%).Major complications were pneumonia(68%),multiple organ dysfunction syndrome(62%),hepatitis(44%),and acute kidney injury(42%).Triglyceride levels were>200 mg/dL in 80% of patients,albumin<3.5 g/dL in 98% and eschar mark was present in 24%of patients.Conclusions:Scrub typhus is a serious acute febrile illness that can lead to multi-organ dysfunction and is associated with significant mortality.Increasing awareness regarding disease in endemic regions,early screening of patients,and treatment as early as possible could help prevent the patient from severe life-threatening complications.

A review of the epidemic and clinical study on scrub typhus in China(2010-2020)

Scrub typhus is an acute febrile vector-borne zoonotic disease caused by the obligate intracellular growth bacterium Orientia tsutsugamushi(Ot).Mites are the primary vectors and rodents play a pivotal role in the transmission of scrub typhus.Due to the climate warming,increased human activity and other factors,cases of scrub typhus have been increased sharply during the past decade in China,especially in the northern China.To understand the incidence trend,epidemic pattern,clinical sign,diagnosis and therapy of this diseases as well as genotype evolution of Orientia tsutsugamushi,we summarized and analyzed the current knowledge of scrub typhus in China from 2010 to 2020.The data indicated that the dominate genotypes of scrub typhus in China were Karp,Kato and Gilliam.Although the disease was distributed national wide,Yunnan,Guangzhou and Fujian showed the highest incidence rate.The main vector of scrub typhus in southwest,middle east and southeast of China appeared a geographic preference respectively.Seasonal timing,age and occupation were the key factors that relate to the peak incidence of scrub typhus.Notably,farmer was the occupation with the highest risk of Ot infection.Further study on the epidemic characteristics,risk factors,diagnosis and treatments of scrub typhus will be of benefit to a comprehensive guideline for prevention and control of this ancient disease.

Scrub typhus:pathophysiology,clinical manifestations and prognosis

Scrub typhus is a zoonosis caused by the pathogen Orientia tsutsugamushi(O.tsvtsugamushi). The disease has significant prevalence in eastern and Southeast Asia.Usually presenting as an acute febrile illness,the diagnosis is often missed because of similarities with oilier tropical febrile infections.Many unusual manifestations are present,and these are described in this review,together with an outline of current knowledge of pathophysiology.Awareness of these unusual clinical manifestations will help the clinician to arrive at an early diagnosis,resulting in early administration of appropriate antibiotics.Prognostic indicators for severe disease have not yet been clearly established.

Comparison of a rapid diagnostic test and microimmunofluorescence assay for detecting antibody to Orientia tsutsugamushi in scrub typhus patients in China

Objective:To evaluate the detection of IgM and IgG antibodies to Orientia tsutsugamushi(O. tsutsugamushi) by rapid diagnostic test(RDT) and microimmunofluorescence assay(ml FA). Methods:RDT using a mixture of recombinant 56-kDa proteins of O.tsutsugamushi and mIFA assay were performed on 20 patients from Fujian and 13 patients from Yunnan Province,and 82 sera samples from healthy farmers in Anhui Province and Beijing City in 2009.Comparison of the RDT and mIFA assay was performed by using X test and the P level of 【0.05 was considered to be significance.Results:Among these 82 normal sera samples,the specificity of RDT was 100%for both IgM and IgG tests.In 33 samples from patients with scrub typhus,5 cases were positively detected earlier by RDT than by mIFA in IgM test,and 2 cases were positive in IgG test.Sensitivities of RDT were 93.9%and 90.9%for IgM and IgG,respectively.The sensitivity of combination lest of IgM and IgG was 100%.Geometric mean titer diluted sera from confirmed cases by IFA and RDT assay were 1:37 vs.1:113(P【0.001) in IgM test and 1:99 vs.1:279 (P【0.05) in IgG test.Conclusions:RDT is more sensitivite than mIFA in the early diagnosis of scrub typhus and it is particularly applicable in rural areas.

Circulatory and hepatic failure at admission predicts mortality of severe scrub typhus patients: A prospective cohort study

Objective:To study the spectrum and outcome of severe scrub typhus in adult patients and to predict the hospital mortality by organ failure on admission.Methods:This was a prospective observational cohort study conducted between July 2017 and October 2020 at the medical emergency centre of PGIMER,Chandigarh,India.One hundred and twenty-six patients aged≥13 years were diagnosed with scrub typhus.Severe disease was defined as the presence of organ failure based on the Sequential Organ Failure Assessment(SOFA)score on admission.Results:About two-thirds of the patients were from geographic regions outside the endemic sub-Himalayan belt.Fever(99.21%)and dyspnea(79.36%)were the most frequent complaints.Respiratory failure(81.75%)was the most common organ failure,followed by hepatic(52.38%),coagulative(47.62%),circulatory(33.33%),renal(21.43%),and cerebral dysfunction(13.49%).The median(Q1,Q3)SOFA score was 8(6,9),and 48.41%of the patients had a quick-SOFA score≥2.Organ supports with invasive ventilation(40.48%),vasopressors(36.51%),and renal replacement therapy(7.14%)were frequently required.The in-hospital mortality was 11.90% and was independently predicted by circulatory and hepatic failures on multivariate logistic regression(OR 11.12,95%CI 1.73-71.31 and OR 8.49,95%CI 1.18-61.41,respectively).Conclusions:Most patients had pulmonary dysfunction;circulatory or hepatic failure on admission strongly predicts death.

Massive small bowel bleeding caused by scrub typhus in Korea

A 79-year-old man was diagnosed with scrub typhus based on fever,eschar,skin rash and a markedly elevated serum tsutsugamushi antibody and doxycycline was started.Five days later,hematochezia developed and multiple small bowel ulcerations with hemorrhage were seen on colonoscopy.Despite intensive therapy,the massive hematochezia worsened and the distal small bowel was resected.Multiple ulcerated lesions were identified pathologically as vasculitis caused by scrub typhus.This is the first reported case of pathologically proven small bowel involvement in scrub typhus infection.

Spectrum of cardiac manifestations and its relationship to outcomes in patients admitted with scrub typhus infection

AIM To study the spectrum of cardiac manifestations in scrub typhus infection and assess its relationship to outcomes.METHODS Demographic data, electrocardiographic(ECG) changes, left ventricular (LV) systolic and diastolic function, myocardial injury (defined as troponin T > 14 pg/mL), and pericardial effusion were documented. Myocarditis was diagnosed when myocardial injury was associated with global LV systolic dysfunction. The relationship between myocarditis and outcomes was assessed using logistic regression analysis and expressed as odds ratio(OR) with 95%CI.RESULTS The cohort(n = 81; 35 males) aged 49.4 ± 16.1 years(mean, SD) presented 8.1 ± 3.1 d after symptom onset. The APACHE-Ⅱ score was 15.7 ± 7.0. Fortyeight (59%) patients were ventilated, and 46 (56%) required vasoactive agents. Mortality was 9.9%. ECG changes were non-specific; sinus tachycardia was the most common finding. Myocardial injury was evident in 61.7% of patients and LV systolic dysfunction in 30.9%. A diagnosis of myocarditis was made in 12.3%. In addition, seven patients with regional wall motion abnormalities had LV systolic dysfunction and elevated cardiac enzymes. Mild diastolic dysfunction was observed in 18 (22%) patients. Mild to moderate pericardial effusion was seen in 51%. On multivariate logistic regression analysis, patients with myocarditis tended to be older (OR = 1.04, 95%CI: 0.99-1.09), had shorter symptom duration (OR = 0.69, 95%CI: 0.49-0.98), and tended to stay longer in hospital(OR = 1.17, 95%CI: 0.98-1.40). Myocarditis was not associated with increased mortality.CONCLUSION In scrub typhus infection, cardiac manifestations are frequent and associated with increased morbidity but not mortality.

Public knowledge,practices and perceptions on typhus fevers in Southern Sri Lanka

Objective:To assess public knowledge,practices and perceptions on typhus fevers in Sri Lanka.Methods:A descriptive study was done in four selected typhus-prone areas in Southern Sri Lanka.A mixed-method was employed using face-to-face interviews and questionnaire-based surveys among confirmed cases of typhus and at-risk populations,respectively.Frequencies,percentages,and means were used to characterize socio-demography and evaluate disease awareness.Results:The lay terms for typhus fevers reported in the studied region were“peacock fever”,“tick fever”and“bird fever”.A total of 499 subjects participated[mean±SD,(45±16)years]in the questionnaire-based survey,and 13.6%(n=68)reported past experience of typhus fever,1.2%(n=6)identified the disease as“typhus”while 58.7%(n=293)and 11.8%(n=59)knew it as‘peacock fever’and‘tick fever’,respectively.The etiological agent was unknown to 95.2%(n=475),but 53.5%(n=267)were aware that it was vector-borne.Fever(57.3%,n=286),eschar(35.7%,n=178),headache(22.0%,n=267)and myalgia(19.2%,n=96)were identified as key symptoms.Past disease experience was significantly associated with higher awareness of the main disease symptoms(fever:χ^(2)=15.713,P<0.001;headache:χ^(2)=19.447,P<0.001;lymphadenopathy:Fisher’s exact test,P=0.023;eschar:χ^(2)=12.049,P<0.001).None knew of any disease prevention methods.Participants with a past history of typhus fever had sought treatment at state hospitals(55.9%,38/68)and private sector hospitals(5.9%,4/68).Conclusions:Public awareness on preventive practices for typhus fevers was rare among the participants though vector-borne aspect was known to many.Clinical disease awareness was deficient among those without past experience of typhus fever.Community sensitization on vector avoidance strategies is highly recommended.

Neglected scrub typhus:An updated review with a focus on omics technologies

Scrub typhus is a neglected disease and one of the most serious health problems in the Asia-Pacific region.The disease is caused by an obligate intracellular bacteria Orientia tsutsugamushi,which is transmitted by chigger bites or larval mite bites.Scrub typhus is a threat to billions of people worldwide causing different health complications and acute encephalitis in infants and growing children.The disease causes multiple organ failure and mortality rates may reach up to 70%due to a lack of appropriate healthcare.Currently available genome and proteome databases,and bioinformatics methods are valuable tools to develop novel therapeutics to curb the pathogen.This review discusses the state-of-the-art of information about Orientia tsutsugamushi-mediated scrub typhus and delineates the role of omics technologies to develop drugs against the pathogen.The role of proteome-wide in silico approaches for the identification of therapeutic targets is also highlighted.

Manifestation of acute peritonitis and pneumonedema in scrub typhus without eschar:A case report

BACKGROUND Scrub typhus is an acute infectious disease caused by rickettsia infection.The diagnosis is based on eschar,and clinical manifestations can range from asymptomatic to multiorgan dysfunction.CASE SUMMARY We report the case of a 35-year-old man living in Zhuhai,Guangdong,China,who had repeated high fever with a maximum body temperature of 40.2°C and elevated white blood cells and procalcitonin levels.After 7 d of persistent high fever,the patient developed rash,abdominal pain,and symptoms of peritonitis.Within 24 h after admission,the patient developed diffuse peritonitis and pneumonedema,requiring ventilator support in the intensive care unit.However,there was no eschar on the body,and the first Weil-Felix test was negative.Taking into account that the patient had a history of jungle activities,doxycycline combined with meropenem was selected.The patient improved,healed,and was discharged after a week.The diagnosis of scrub typhus was confirmed by a repeat Weil-Felix test(Oxk 1:640),and pathology of the appendix resected by laparotomy suggests vasculitis.CONCLUSION This rare presentation of peritonitis,pulmonary edema,and pancreatitis caused by scrub typhus reminds physicians to be alert to the possibility of scrub typhus.

Association between scrub typhus encephalitis and diffusion tensor tractography detection of Papez circuit injury:A case report

BACKGROUND It is difficult to restore the cognitive functions of patients with impaired cognition caused by brain injury.Diffusion tensor imaging can visualize the integrity of neural tracts in the white matter(WM)three-dimensionally.It is unclear whether encephalitis following scrub typhus damages the WM.For the first time,we aimed to report diffusion tensor tractography(DTT)findings in a chronic patient with cognitive impairment following scrub typhus encephalitis,which revealed injury to the Papez circuit of the WM.CASE SUMMARY A 70-year-old male patient was affected by encephalitis caused by scrub typhus that occurred 23 years ago.He had poor cognition and his clinical examination findings were as follows:Mini-Mental Status Examination score,14;and handgrip strength(right/left,kg),32.3/31.3.DTT revealed serious injuries of the left thalamocingulate tract and right mammillothalamic tract in the Papez circuit,and a partial injury of the anterior part of the fornix.CONCLUSION Using DTT,we found a relationship between cognitive impairment and the integrity of the Papez circuit following scrub typhus.

In Search of Scrub Typhus: A Prospective Analysis of Clinical and Epidemiological Profile of Patients from a Tertiary Care Hospital in New Delhi

Introduction: Scrub typhus is a febrile illness caused by Orientia tsutsugamushi which is transmitted by the larval stage of trombiculid mites. It has varied manifestations ranging from mild disease to fatal illness. The classical manifestations include fever, rash, lymphadenopathy and eschar. Serology is the preferred diagnostic tool with indirect immunofluorescence assay (IFA) as the current gold standard. Material & Methods: A total of 229 clinically suspected cases of Scrub typhus from 15th of October 2013 to 15th of October 2015 were enrolled in the study. Clinical, epidemiological and laboratory data of the patients were collected and analysed. The method for diagnosis was IgM immunofluorescence assay. Results: A total of 33 cases (14.4%) of scrub typhus were detected. Most of the cases (87%) presented in the months of September to November. Fever of >39°C was seen in all 33 cases. Rash and eschar were seen in 24.2% and 18.2% cases, respectively. Lymphadenopathy (18.2%), hepatomegaly (48.5%), splenomegaly (21.2%) and icterus (15.2%) were seen in some cases. Pulmonary manifestations were noted in 69.7% of cases. Acute kidney injury (18.2%), encephalitis (21.2%), and myocarditis (15.15%) were the other complications observed. Common haematological abnormalities noted in patients of scrub typhus were anaemia (45.6%), leucocytosis (45.6%), thrombocytopenia (48.5%) and transaminitis (54.5%). 10 cases were treated by azithromycin while doxycycline was used for treatment in 28 cases. Conclusion: The nonspecific symptoms and lack of classical manifestations make the diagnosis of scrub typhus difficult. There is a definite need to increase awareness and heighten the suspicion, especially in the light of increasing number of patients presenting with atypical manifestations.

A Case Report of Scrub Typhus: Secondary Acute Arrest of Hemopoiesis with Multiple Organ Dysfunction Syndromes

Scrub typhus is a zoonotic disease caused by Orientia tsutsugamushi (O. tsutsugamushi) in which humans are accidental hosts. Acute arrest of hemopoiesis (AAH) always manifests in pancytopenia and with supportive treatment or inducement removal, the AAH patients would show significant improvement in blood routine for about a week. As a rapidly progressive and potentially life-threatening organ function disorder syndrome, multiple organ dysfunction syndrome (MODS) is often induced by many factors including infection, illness and injury. We received a rare case of scrub typhus rapidly presenting with AAH and MODS 2 weeks ago. The clinical data of a 32-year-old female with O. tsutsugamushi-induced AAH and MODS was summarized retrospectively and analyzed with a literature review. In this case, we selected tigecycline and moxifloxacin as treatment regimens for scrub typhus. When the potential infection was controlled, her pancytopenia and hepatic function rapidly improved in a few days.

Molecular epidemic survey on co-prevalence of scrub typhus and marine typhus in Yuxi city,Yunnan province of China

Background Human rickettsioses are worldwide zoonoses and it is not easy to differentiate them from other infectious diseases because of their atypical manifestation. In recent years the number of patients with fever of unknown causes from Hongta District CDC, Yuxi city of Yunnan Province has been increasing significantly in the summer. Diagnosis of scrub typhus was made by local clinicians. In order to ascertain the disease, we undertook a laboratory investigation for such patients from August 18 to 26, 2005. Methods Active surveillance was conducted by Hongta District CDC Yuxi city of Yunnan Province from 2002 to 2004 and basic data were obtained from cases confirmed according to clinical definitions. Average incidences and town-level incidences were calculated during the study periods. Blood samples were analyzed by PCR and serological test. Based on the groEL gene sequences a paired general outer primers （Gro-1 and Gro-2） targeting typhus, spotted fever as well as scrub typhus and two paired inner primers （SF1, SR2 and TF1, TR2） for typhus together with spotted fever and scrub typhus, respectively, were designed to perform a multiplex-nested PCR. Serological assay was carried out by indirect immunofluorescence assay with 7 different rickettsial antigens, i.e., R.mossori, R.sibirica, R.conorii, O.tsutsugamushi, B.quintana, B.henselae and Coxilella burnetii phase Ⅱ Ag. Results Epidemiological surveillance showed that from 2002 to 2004, the average incidences of the scrub typhus or scrub typhus with murine typhus were 222.1/10^5, 204.3/10^5 and 109.6/10^5, respectively. Of 13 blood samples taken during acute stage of illness, 6 showed the amplified products for scrub typhus and the sequenced products showed 100%, 99%, 99%, 99%, 99%, 99% similarity to O.tsutsugamushi Karp but they shared the same deduced amino acid sequences, which indicated 100% identity with the heat shock protein of the O.tsutsugamushi Karp strain. Five yielded PCR products for murine typhus and their corresponding nucleotide sequences exhibited 100%, 100%, 99%, 99% and 99% similarity to R. mossori Wilmington and the analyses of predicted amino acid sequences indicated 100%, 100%, 98%, 98% and 98% identity with the heat shock protein of R. mossoriWilmington strain. Of the 8 PCR positive patients, 3 showed a co-infection of scrub typhus with murine typhus. All the 13 serum samples from febrile patients were positive against O. tsutsugamushi and 8 of them were positive against R. mossori. All of the 8 paired specimens had four-fold elevation of antibody against O. tsutsugamushi, and seroconversion for typhus was demonstrated in 3 paired serum samples. Another finding in the study was that a high seropositive prevalence （76.9%） of Q fever was detected. Concluaion It＇s confirmed that co-prevalence of scrub typhus with murine typhus are occurring in Yuxi city of Yunnan province, China. Other rickettsial diseases also need to be investigated in these areas.

Evaluation of scrub typhus diagnosis in China:analysis of nationwide surveillance data from 2006 to 2016

Background:Scrub typhus is a life-threatening disease caused by O rientia tsu tsu gom u sh i,and specific antimicrobial medicine is available.Early and accurate diagnosis is essential for reducing the risk of severe complications and death.In this study,we aimed to evaluate the case diagnosis situation among medical care institutions and geographical regions in China,and the results will benefit both clinical practice and the disease surveillance system.Methods:We extracted individual scrub typhus case data 2006-2016 from a national disease surveillance system in China.The diagnosis category and interval time from illness onset to diagnosis were compared among three levels of medical care institutions and provinces.The descriptive analysis method was performed in our study.Results:During the 11-year study period,93481 scrub typhus cases,including 57 deaths,were recorded in the nationwide surveillance system.The overall proportion of laboratory-confirmed cases was only 4.7%,and this proportion varied greatly among primary medical centres(2.8%),county level hospitals(4.2%),and city level hospitals(6.3%).Notably,the proportion of laboratory-confirmed cases has consistently decreased from 16.3%in 2006 to 2.6%in 2016,and the same decreasing trend was found among all three levels of medical care institutions.The interval from illness onset to case diagnosis(Tdiag)for all cases was 5 days(interquartile range[IQR]:2-9 days)and decreased from 7 days(IQR:3-11 days)in 2006 to 5 days(IQR:2-8 days)in 2016.The risk of death for patients with a Tdiag of>7 days was 2.2 times higher(OR=22),(95%CI:1.05-5.21)than that of patients with a Tdiag of<2 days.Conclusions:The interval time from illness onset to diagnosis for scrub typhus cases decreased greatly in China;however,the diagnosis rate of cases with laboratory-confirmed results must be increased among all levels of medical care institutions to reduce both the risk of death and the misuse of antibiotics associated with scrub typhus.

Clinical and paraclinical profile, and predictors of outcome in 90 cases of scrub typhus, Meghalaya, India

Background:India is an integral component of“tsutsugamushi triangle”which depicts a part of the globe endemic to scrub typhus.Owing to frequent outbreaks witnessed in different parts of the country in the recent past,scrub typhus is described as a re-emerging infectious disease in India.The present study aimed to study the clinical and paraclinical profile,complications and predictors of outcome among 90 cases of scrub typhus diagnosed in a hospital of north-eastern India from Sept 2011 to Aug 2012.Methods:A longitudinal study was conducted in a hospital of Meghalaya,India between Sept 2011 and Aug 2012.Diagnosis of scrub typhus was arrived by SD BIOLINE tsutsugamushi(solid phase immunochromatographic assay)rapid diagnostic test for antibodies(IgM,IgG or IgA).Descriptive analyses of age,gender,geographic area,symptoms and signs,treatment,laboratory findings,complications,and outcome were conducted.Relative risk(RR)with 95%confidence interval(CI)was computed for Multiple Organ Dysfunction Syndrome(MODS)and mortality.Binary logistic regression was applied to the significant correlates(P<0.05)on univariate analysis to identify the predictors of MODS and mortality in scrub typhus.Results:As many as 662 clinically suspected scrub typhus patients were tested and 90(13.6%)were diagnosed to have scrub typhus.Out of 90 patients,52.2%(n=47)were males and their mean(SD)age was 36.29(13.38)years.Fever of<7 days(n=75,83.3%),myalgia(n=56,62.2%),pain abdomen(n=24,26.7%),headache(n=24,26.7%),nausea/vomiting(n=21,23.3%),dry cough(n=21,23.3%),hepatomegaly(n=24,26.7%),splenomegaly(n=22,24.4%),and lymphadenopathy(n=20,22.2%)were the predominant clinical features.Eschar was seen in 10 patients(11.1%).One third(n=30)of the patients developed at least one systemic complication.Acute hepatitis(n=15,16.7%),pneumonitis(n=14,15.6%),and acute kidney injury(n=11,12.2%)were the common complications.MODS was seen in 14.4%(n=13)and 38.5%(n=5)of the patients with MODS died.Overall,case fatality rate was 5.15%(n=5).On univariate analysis,platelets<100000/mm3,serum creatinine>1.5 mg/dl,and transaminase(AST,ALT or both)>500 U/L were associated with MODS(P<0.001)and mortality(P<0.05).In addition,serum bilirubin>3 mg/dl was also associated with MODS(P<0.001).On applying binary logistic regression,serum creatinine>1.5 mg/dl was a predictor of MODS(OR:76.1,95%CI:4.9–1175.6)and mortality(OR:18.03,95%CI:1.38–235.1).Conclusion:In this study setting,approximately one-seventh(13.6%)of the acute undifferentiated febrile illness were due to scrub typhus.Systemic complications were common(33.3%).Serum creatinine>1.5 mg/dl was a predictor of MODS and mortality.

Ecological and behavioural risk factors of scrub typhus in central Vietnam:a case-control study

Background The risk factors for scrub typhus in Vietnam remain unknown.Scrub typhus caused by Orientia tsutsugamushi often presents as an undifferentiated febrile illness and remains under appreciated due to the limited availability of diagnostic tests.This tropical rickettsial illness is increasingly recognized as an important cause of non-malaria acute undifferentiated fever in Asia.This study aimed to investigate behavioural and ecological related risk factors of scrub typhus to prevent this potentially life-threatening disease in Vietnam.Methods We conducted a clinical hospital-based active surveillance study,and a retrospective residence-enrolment date-age-matched case–control study in Khanh Hoa province,Vietnam,from August 2018 to March 2020.Clinical examinations,polymerase chain reaction and enzyme-linked immunosorbent assay IgM tests were applied to define cases and controls.All enrolled participants filled out a questionnaire including demographic socio-economic status,personal behaviors/protective equipment,habitat connections,land use,and possible exposure to the vector.Multivariable conditional logistic regression was used to define the scrub typhus associated risk factors.Results We identified 44 confirmed cases and matched them with 152 controls.Among cases and controls,the largest age group was the 41–50 years old and males accounted for 61.4%and 42.8%,respectively.There were similarities in demographic characteristics between the two groups,with the exception of occupation.Several factors were significantly associated with acquisition of scrub typhus,including sitting/laying directly on household floor[adjusted OR(aOR)=4.9,95%CI:1.6–15.1,P=0.006],household with poor sanitation/conditions(aOR=7.9,95%CI:1.9–32.9,P=0.005),workplace environment with risk(aOR=3.0,95%CI:1.2–7.6,P=0.020),always observing mice around home(aOR=3.7,95%CI:1.4–9.9,P=0.008),and use of personal protective equipment in the field(aOR=0.4,95%CI:0.1–1.1,P=0.076).Conclusions Ecological and household hygiene-related factors were more associated with scrub typhus infection,than individual-level exposure activities in the hyper-endemic area.These findings support local education and allow people to protect themselves from scrub typhus,especially in areas with limitations in diagnostic capacity.

Diagnostic evaluation of rapid tests for scrub typhus in the Indian population is needed

Background:Owing to frequent outbreaks witnessed in different parts of the country in the recent past,scrub typhus is being described as a re-emerging infectious disease in India.Differentiating scrub typhus from other endemic diseases like malaria,leptospirosis,dengue fever,typhoid,etc.is difficult due to overlapping clinical features and a lower positivity for eschars in Asian populations.Hence,the diagnosis heavily relies on laboratory tests.Discussion:Costs and the need of technical expertise limit the wide use of indirect immunoperoxidase or immunofluorescence assays,ELISA and PCR.The Weil-Felix test is the most commonly used and least expensive serological test,but lacks both sensitivity and specificity.Hence,the diagnosis of scrub typhus is often delayed or overlooked.With due consideration of the cost,rapidity,single test result and simplicity of interpretation,rapid diagnostic tests have come into vogue.However,evaluation of rapid diagnostic tests for scrub typhus in the Indian population is needed to justify or discourage their use.Conclusion:Research studies are needed to find the most suitable test in terms of the rapidity of the result,simplicity of the procedure,ease of interpretation and cost to be used in the Indian populace.

Surveys of rodent-borne disease in Thailand with a focus on scrub typhus assessment

The epidemiology of many rodent-borne diseases in South-East Asia remains ill-defined.Scrub typhus and lep-tospirosis are common and medically significant,while other zoonotic diseases,such as spotted fever group Rickettsiae have been identified,but their overall medical significance is unknown.Rodent surveillance was con-ducted from June 2002 to July 2004 in 18 provinces from Thailand.Traps were set up for one to three nights.Blood and serum samples and animal tissue samples(liver,spleen,kidney and urinary bladder)were collected.Chigger-mites,ticks and fleas were removed from captured rodents.Atotal of 4536 wild-caught rodents from 27 species were captured over two years of animal trapping.Rattus rattus was the dominant species,followed by Rattus exulans and Bandicota indica.Almost 43000 ectoparasites were removed from the captured animals.Approximately 98%of the ectoparasites were chigger-mites,of which 46%belonged to the genus Leptotrombidium(scrub typhus vector).Other genera included Schoengastia and Blankaartia.Tick and flea specimens together comprised less than 1%of the sample.Among the five species of ticks collected,Haemaphysalis bandicota was the predominant species caught,followed by Ixodes granulatus other Haemaphysalis spp.,Rhipicephalus spp.and Dermacentor spp.Only two species of fleas were collected and Xenopsylla cheopis(rat flea)was the predominant species.Using both commercial diagnostic kits and in-house molecular assays,animal tissue samples were examined and screened for zoonotic diseases.Seven zoonotic diseases were detected:scrub typhus,leptospirosis,murine typhus,tick typhus,bartonella,babesiosis and trypanosomiasis.Most samples were positive for scrub typhus.Other zoonotic diseases still under investigation include borrelosis,ehrlichiosis,the plague,and other rickettsial diseases.Using geo-graphic information systems,global positioning systems and remote sensing technology,epidemiological and environmental data were combined to assess the relative risk in different biotopes within highly endemic areas of scrub typhus in Thailand.