An immunochromatographic test for serological diagnosis of scrub typhus

A fluorescent immunochromatographic test (FM-ICT) was developed for rapid detection of anti-Orientia tsutsugamushi antibodies in serum samples. The FM-ICT was constructed based on the dual-antigen sandwich method. Truncated 56 kDa outer membrane protein of O. tsutsugamushi strain SJ, was expressed in E. coli and mixed with those of Ptan and Gillam strains. A thin line of the protein mixture was precisely sprayed across a nitrocellulose membrane making this the "Test" line. Polyclonal antibodies (pAbs) to O.tsutsugamushi were sprayed in another line across the membrane making this the "Control" line. Fluorescent microspheres conjugated 56 kDa proteins reacting with sample serum will be captured on the "Test" line if the sample contains antibodies to O.tsutsugamushi. Several experimental parameters were optimized. After optimizing the reaction procedure, the results are visible, within 6 min, with the naked eye under ultraviolet light. The limit of detection (LOD) was determined to be 7.63 ng/mL with prepared polyclonal antibodies. No cross-reaction was observed with sera samples from other febrile diseases. In clinical evaluations, the strips showed 94.92% sensitivity (106/112) and 93.75% specificity (56/60). The FM-ICT we developed will provide a new tool for on-site diagnosis of scrub typhus.

Guillain-Barre syndrome following scrub typhus: a case report and literature review

BACKGROUND

Scrub typhus is an acute infectious disease caused by Orientia tsutsugamushi. Guillain-Barre syndrome (GBS) is an autoimmune-mediated peripheral neuropathy with a frequent history of prodromal infections, but GBS associated with scrub typhus is very rare.

CASE PRESENTATION

We report a 51-year-old male patient who developed dysarthria and peripheral facial paralysis following the cure of scfrub typhus. CSF examination and electrophysiological findings suggested a diagnosis of GBS. After treatment with intravenous immunoglobulin, the patient's neurological condition improved rapidly.

CONCLUSIONS

Scrub typhus infection is likely to be a potential predisposing factor in GBS, while scrub typhus-associated GBS has a favorable prognosis.

Molecular epidemiological study of Scrub Typhus in residence, farm and forest habitats from Yunnan Province, China

The number of people suffering from scrub typhus, which is not of concern, is increasing year by year, especially in Yunnan Province, China. From June 1, 2021 to August 15, 2022, a total of 505 mammalian samples were collected from farm, forest, and residential habitats with high incidence of scrub typhus in Yunnan, China, for nPCR (nested PCR) and qPCR (quantitative real-time PCR) detection of Orientia tsutsugamushi. A total of 4 orders of murine-like animals, Rodentia (87.52%, n = 442), Insectivora (10.29%, n = 52), Lagomorpha (1.79%, n = 9) and Scandentia (0.40%, n = 2) were trapped. Comparing the qPCR infection rates in the three habitats, it was no significant difference that the infection rate of residential habitat (44.44%) and that of the farm habitat (45.05%, P>0.05), which is much larger than that of the forest habitat (3.08%) (P<0.001). Three genotypes (Karp-like, Kato-like and TA763-like) of O. tsutsugamushi were found from Yunnan, China in this study.

Development and implementation of a strategy for early diagnosis and management of scrub typhus: an emerging public health threat

Scrub typhus, caused by Orientia tsutsugamushi, is a re-emerging zoonotic disease in the tropics with considerable morbidity and mortality rates. This disease, which is mostly prevalent in rural areas, remains underdiagnosed and underreported because of the low index of suspicion and non-specific clinical presentation. Limited access to healthcare, diagnostics, and treatment in rural settings further makes it challenging to distinguish it from other febrile illnesses. While easily treatable, improper treatment leads to severe forms of the disease and even death. As there is no existing public health program to address scrub typhus in India, there is an urgent need to design a program and test its effectiveness for control and management of the disease. With this backdrop, this implementation research protocol has been developed for a trial in few of the endemic "pockets" of Odisha, an eastern Indian state that can be scalable to other endemic areas of the country, if found effective. The main goal of the proposed project is to include scrub typhus as a differential diagnosis of fever cases in every tier of the public health system, starting from the community level to the health system, for the early diagnosis among suspected cases and to ensure that individuals receive complete treatment. The current study aimed to describe the protocol of the proposed Scrub Typhus Control Program (STCP) in detail so that it can receive valuable views from peers which can further strengthen the attempt.

Epidemiology of Murine Typhus in Taiwan from 2013 to 2020

Murine typhus is a flea-borne disease caused by Rickettsia typhi infection. The disease is a notifiable infectious disease in Taiwan. Specimens from suspected cases are required to be sent to the Taiwan Centers for Disease Control and Prevention for laboratory diagnosis. In this study, 204 cases of murine typhus were identified by bacterial isolation, real-time polymerase chain reaction, or indirect immunofluorescence assay between 2013 and 2020. The average incidence rate was 0.11/100,000 person-years (95% CI: 0.08-0.13). Murine typhus occurred throughout the year, but it was most prevalent in summer (May to August). The majority of patients were males (75%), residents of Kaohsiung city (31%), and worked in agriculture, forestry, fishing, and animal husbandry (27%). Fever was the most common symptom, present in 95.6% of patients, followed by headache (41%), myalgia (33%), and liver dysfunction (33%). Only 13% of patients had a rash. Up to 80% of cases were among hospitalized patients, and 43% of patients developed severe manifestations. Serological assays also indicated coinfection events. Seven patients showed a 4-fold increase in antibody titers against Orientia tsutsugamushi (N = 2), Coxiella burnetii (n = 2), and Leptospira (N = 3). In conclusion, murine typhus is an endemic and important zoonotic rickettsial disease in Taiwan that cannot be ignored. Further epidemiological surveillance and clinical characteristics should be continuously investigated to prevent and control murine typhus.

Digital Gangrene Associated with Scrub Typhus: A Case Series

Rickettsial diseases cover a broad spectrum of illnesses. Scrub typhus is present worldwide, and Orientia tsutsugamushi is the causative agent of this chigger mite-borne infectious illness. Infections exhibit a range of severity, from mild illness to the more severe manifestation of multiorgan failure. We report three cases of scrub fever (55-year-old female, 63-year-old female, and 29-year-old male), all cases developed focal or pan-digital gangrene. All cases were successfully treated by administering doxycycline and additional supportive measures. Digital gangrene is uncommon in scrub typhus. Clinical suspension for early diagnosis and appropriate treatment may avoid further complications.

Scrub typhus in Northeast India: epidemiology, clinical presentations, and diagnostic approaches

Scrub typhus is one of the most neglected tropical diseases, a leading cause of acute undifferentiated febrile illness in areas of the 'tsutsugamushi triangle', diagnosed frequently in South Asian countries. The bacteria Orientia tsutsugamushi is the causative agent of the disease, which enters the human body through the bite of trombiculid mites (also known as chiggers) of the genus Leptotrombidium deliense. Diagnosis of the disease is challenging, as its early symptoms mimic other febrile illnesses like dengue, influenza and corona viruses. Lack of rapid, reliable and cost-effective diagnostic methods further complicates the identification process. Northeast India, a mountainous region with a predominantly rural tribal population, has witnessed a resurgence of scrub typhus cases in recent years. Various ecological factors, including rodent populations, habitat characteristics and climatic conditions, influence its prevalence. Entomological investigations have confirmed the abundance of vector mites, highlighting the importance of understanding their distribution and the probability of transmission of scrub typhus in the region. Proper diagnosis, awareness campaigns and behavioural interventions are essential for controlling scrub typhus outbreaks and reducing its impact on public health in Northeast India. Further research and community-based studies are necessary to accurately assess the disease burden and implement effective prevention strategies.

Changing epidemiologic patterns of typhus group rickettsiosis and scrub typhus in China, 1950-2022

OBJECTIVES

We conducted a systematic analysis of the notifiable rickettsial diseases in humans in China during 1950-2022.

METHODS

We utilized descriptive statistics to analyze the epidemiological characteristics, clinical manifestations, and diagnostic characteristics of typhus group rickettsiosis (TGR) and scrub typhus (ST) cases.

RESULTS

Since the 1950s, there have been variations in the incidence rate of TGR and ST in China, with a downtrend for TGR and an uptrend for ST. The South became a high-incidence area of TGR, whereas the North was previously the high-incidence area. ST cases were concentrated in the South and the geographic area of ST spread northward and westward. The seasonality of TGR and ST were similar in the South but distinct in the North. Most TGR and ST cases were reported by county-level medical institutions, whereas primary institutions reported the least. Delayed diagnosis was associated with fatal outcomes of TGR and ST. Cases in low-incidence provinces, confirmed by laboratory tests and reported from county/municipal-level institutions had higher odds of delayed diagnoses.

CONCLUSIONS

Our study revealed significant changes in the epidemiological characteristics of TGR and ST in China, which can provide useful information to enhance the control and prevention strategies of rickettsial diseases in China.

Clinical and laboratory findings in scrub typhus associated Guillain-Barré syndrome in South Korea

BACKGROUND AND AIMS

Scrub typhus is an endemic disease in the fall season that occurs in a limited number of places known as the Tsutsugamushi Triangle. Peripheral neuropathy is a common complication of scrub typhus. Herein, we encountered several patients with ascending paralysis after scrub typhus infection, who were diagnosed with Guillain-Barré syndrome (GBS). We aimed to investigate the clinical and laboratory characteristics of patients who developed GBS after scrub typhus.

METHODS

Patients were retrospectively recruited from six nationwide tertiary centers in South Korea from January 2017 to December 2021. Patients who had been clinically diagnosed with GBS and confirmed to have scrub typhus via laboratory examination and/or the presence of an eschar before the onset of acute limb paralysis were included. The GBS-associated clinical and electrophysiological characteristics, outcomes, and scrub typhus-associated features were collected.

RESULTS

Of the seven enrolled patients, six were female and one was male. The median time from scrub typhus infection to the onset of limb weakness was 6 (range: 2-14) days. All patients had eschar on their bodies. Four patients (57.1%) were admitted to the intensive care unit and received artificial ventilation for respiratory distress. At 6 months, the median GBS disability score was 2 (range, 1-4) points.

INTERPRETATION

Patients with scrub typhus-associated GBS have a severe clinical presentation and require intensive treatment with additional immunotherapies. Therefore, GBS should be included in the differential diagnosis when peripheral neuropathies develop during scrub typhus treatment. Notably, scrub typhus is associated to GBS.

Integration of IgM ELISA and 56 kDa gene PCR in management of pediatric acute encephalitis syndrome associated with scrub typhus

OBJECTIVES

To identify the potential target genes for detection of Orientia tsutsugamushi (OT) in pediatric acute encephalitis syndrome (pAES).

METHODS

DNA was extracted from whole blood of 100 pAES cases having tested positive (n = 41) and negative (n = 59) for scrub typhus (ST) by IgM ELISA. These samples were subjected to standard PCR for 56 kDa, 47 kDa, 16 s rRNA, groEL, traD genes and the newly identified 27 kDa gene.

RESULTS

Among the selected gene targets, 56 kDa demonstrated its superiority for OT detection over the other tested genes. The presence of OT was confirmed via PCR targeting 56 kDa gene in 17 out of the 41 (41.4 %) IgM-positive ST AES cases and 38 out of the 59 (64.4 %) ST IgM negative cases. None of the other gene targets were amplified.

CONCLUSION

Integration of serological diagnosis with molecular diagnostics targeting the 56 kDa gene for routine testing of AES patients would facilitate detection of OT in AES endemic regions.

A case of neonatal tsutsugamushi disease diagnosed with the aid of rickettsial macrogenomic detection

BACKGROUND

Tsutsugamushi, also known as bush typhus, is a naturally occurring disease caused by Orientia tsutsugamushi. We reported a case of vertical mother-to-newborn transmission of Orientia tsutsugamushi infection in a newborn from Yunnan (China).

CASE PRESENTATION

Decreased fetal movements were observed at 39 weeks of gestation. After birth, the newborn (female) had recurrent fever, shortness of breath, and bruising around the mouth and extremities. At 5 h 58 min of age, the newborn was admitted for fever, shortness of breath and generalized rash. The liver was palpable 3 cm below the costal margin, and the limbs showed pitting edema. There was subcutaneous bleeding. Investigations suggested heavy infection, myocardial damage, decreased platelets. Treatment with cefotaxime and ampicillin failed. The mother was hospitalized at 29 weeks of gestation with a fever for 4 consecutive days, and an ulcerated crust was found in the popliteal fossa. Due to this pregnancy history, A diagnosis of Orientia tsutsugamushi infection was suspected in our index case and confirmed by macrogenomic testing and she was treated with vancomycin and meropenem, and later azithromycin for 1 week. The newborn was discharged in good general condition, gradually normalizing body temperature, and decreasing rash and jaundice. There were no abnormalities on subsequent blood macrogenomic tests for the baby. And one month later she showed good mental health, sleep, and food intake and no fever, rash, or jaundice.

CONCLUSION

Determining the cause of symptoms is the key to treating diseases, especially the rare diseases that can be misdiagnosed.

SUITABLE FOR PEOPLE WITH

Infectious Diseases; Neonatology; Obstetrics.

Transmission Cycle of Shimokoshi-Type Orientia tsutsugamushi in Shimane Prefecture, Japan

To demonstrate the transmission cycle of Shimokoshi-type Orientia tsutsugamushi in Shimane Prefecture, field rodents were captured from areas where four human infections caused by the pathogen have been reported. The rodents were investigated for the transmission cycle of the pathogen based on the pathogen's genome, antibodies against the pathogen, and the vector of the pathogen (Leptotrombidium palpale). In addition, the vector was captured from the soil in the study area. A total of 44 rodents were captured. No O. tsutsugamushi DNA was detected in the blood or spleen samples by real-time polymerase chain reaction. However, a specific antibody against the pathogen was detected in 2 out of 44 (4.5%) rodents using the indirect immunoperoxidase method, indicating the presence of the pathogen in the study area. Although 29 L. palpale were identified, DNA detection was not performed because of the insufficient number of vectors, based on the DNA detection rate in previous studies. However, the identification of the vector, as well as the specific antibody in rodents, suggests the presence of the transmission cycle of Shimokoshi-type O. tsutsugamushi in Shimane Prefecture.

Spontaneous splenic rupture associated with scrub typhus: a case report

BACKGROUND

Scrub typhus, an acute febrile disease with mild to severe, life-threatening manifestations, potentially presents with a variety of complications, including pneumonia, acute respiratory distress syndrome, cardiac arrhythmias (such as atrial fibrillation), myocarditis, shock, peptic ulcer, gastrointestinal bleeding, meningitis, encephalitis, and renal failure. Of the various complications associated with scrub typhus, splenic rupture has rarely been reported, and its mechanisms are unknown. This study reports a case of scrub typhus-related spontaneous splenic rupture and identifies possible mechanisms through the gross and histopathologic findings.

CASE PRESENTATION

A 78-year-old man presented to our emergency room with a 5-day history of fever and skin rash. On physical examination, eschar was observed on the left upper abdominal quadrant. The abdomen was not tender, and there was no history of trauma. The Orientia tsutsugamushi antibody titer using the indirect immunofluorescent antibody test was 1:640. On Day 6 of hospitalization, he complained of sudden-onset left upper abdominal quadrant pain and showed mental changes. His vital signs were a blood pressure of 70/40 mmHg, a heart rate pf 140 beats per min, and a respiratory rate of 20 breaths per min, with a temperature of 36.8 °C. There were no signs of gastrointestinal bleeding, such as hematemesis, melena, or hematochezia. Grey Turner's sign was suspected during an abdominal examination. Portable ultrasonography showed retroperitoneal bleeding, so an emergency exploratory laparotomy was performed, leading to a diagnosis of hemoperitoneum due to splenic rupture and a splenectomy. The patient had been taking oral doxycycline (100 mg twice daily) for 6 days; after surgery, this was discontinued, and intravenous azithromycin (500 mg daily) was administered. No arrhythmia associated with azithromycin was observed. However, renal failure with hemodialysis, persistent hyperbilirubinemia, and multiorgan failure occurred. The patient did not recover and died on the fifty-sixth day of hospitalization.

CONCLUSIONS

Clinicians should consider the possibility of splenic rupture in patients with scrub typhus who display sudden-onset abdominal pain and unstable vital signs. In addition, splenic capsular rupture and extra-capsular hemorrhage are thought to be caused by splenomegaly and capsular distention resulting from red blood cell congestion in the red pulp destroying the splenic sinus.

Case report of scrub typhus with bilateral acute sensorineural hearing loss and cerebral salt-wasting disease

Scrub typhus is a re-emerging and endemic disease in the Asia Pacific region caused by Orientia tsutsugamushi. We present a 65-year-old male from Sri Lanka who presented with fever, bilateral acute sensorineural hearing loss, and confusion. On examination, he was dehydrated. Significant orthostatic hypotension and an eschar were noted. Investigations revealed hyponatraemia with elevated urine sodium, reduced serum osmolality, and normal urine osmolality suggestive of cerebral salt wasting. After initial hydration with 0.9% NaCl, hyponatraemia was corrected with 3% NaCl. Oral doxycycline was prescribed, and he showed dramatic clinical improvement. A diagnosis of typhus must be considered in a patient presenting with a febrile illness and acute hearing loss. Cerebral salt-wasting disease should be considered in a patient with typhus who develops hyponatraemia with dehydration. Furthermore, acute sensorineural hearing loss in both ears is an important manifestation of the disease.

Comparative analysis of diagnostic assays for scrub typhus: Unveiling enhanced approaches for accurate detection

The study comparatively evaluated serological assays, namely, Weil Felix assay, and IgM ELISA with the gold-standard immunofluorescence test (IFAT) for the sensitive and specific serodiagnosis of scrub typhus infection in occupationally exposed groups of humans. A total of 78 serum samples collected from persons affected with various ailments and belonging to different risk groups were screened in the study. Out of the 78 serum samples tested, a total of 17, 26, and 47 samples turned out to be positive by IFAT, IgM ELISA, and Weil Felix test, respectively. The Weil Felix assay could not serve as an ideal test for screening scrub typhus infection owing to its poor sensitivity and specificity in comparison with IFAT. IgM-ELISA could be an initial screening test to detect scrub typhus suspected patient in limited resource settings.

Human rickettsial infections in India - A review

Rickettsial infections are emerging and/or re-emerging disease that poses a serious global threat to humans and animals. Transmission to humans and animals is through the bite of the ectoparasites including ticks, fleas and chigger mites. Most of the rickettsial diseases are endemic in India, but underdiagnosed. This review is aimed at analyzing the prevalence of rickettsiosis in India and the advancement of rickettsial diagnosis. We have conducted a systematic review on the prevalence of rickettsial disease in India ranging from 1.3% to 46.6% for spotted fever, 2.4% to 77.8% for scrub typhus and 1% to 46.4% for Q fever, based on the literature published with the evidence of isolation, serological, and molecular diagnostics. Search engines Medline/PubMed, Science Direct, ProQuest, and EBSCO were used to retrieve the articles from electronic databases by using appropriate keywords to track the emergence of these rickettsial diseases in India for the period of 1865 to till date. We retrieved 153 published rickettsial articles on hospital-based studies from India that were purely made on the basis of prevalence and the laboratory parameters viz., Weil-Felix test (WF) and Rapid Immunochromatographic tests (RICT) with reference to the gold standard IFA and ELISA. More epidemiological studies are required for epidemic typhus to know the exact prevalence status of this louse-borne rickettsiosis in India. Currently, there is no confirmed specific inflammatory marker for rickettsial diseases. Moreover, serological cross-reactivity is an important aspect, and it should be investigated in endemic areas, there is also a need to include molecular diagnostic techniques for further confirmation in healthcare settings.

Diagnostic challenges and antibody kinetics in a paediatric traveller with scrub typhus

Diagnosing scrub typhus in travellers is challenging due to symptom similarities with other travel-related illnesses and limited early diagnostic tools. We present a distinctive case of scrub typhus in a child traveller, providing a comprehensive account of the case, the diagnostic challenges encountered, laboratory findings and the dynamics of antibodies.

Clinical and Laboratory Characteristics of Patients with Mono and Coinfection of Dengue and Scrub typhus

BACKGROUND

Dengue is a neglected tropical disease, and Scrub typhus is an emerging tropical illness in Nepal. Coinfection between them is found in literature and clinical practice. The objective of this study is to describe and compare the demographic, clinical, and laboratory characteristics of patients with mono and coinfection of Dengue and Scrub typhus.

METHODS

This was a single-center hospital-based retrospective study, performed at Beni District Hospital, Nepal. The patient who was diagnosed with mono and coinfection of Dengue and Scrub typhus from 1st January 2020 to 16th September 2020 were included. Data regarding demographic characteristics, symptoms, signs, and laboratory parameters were collected and analyzed.

RESULTS

In 53 patients who fall under the inclusion criteria of our study, 12 patients had coinfection with dengue and Scrub typhus with headache being the most common symptom regardless of mono or coinfection followed by myalgia and arthralgia. Total platelet counts at the time of admission were lower in the coinfection group with increasing thrombocytopenia during the disease course in comparison to mono-infection. The maximum temperature recorded, elevation in hepatic enzymes, and duration of defervescence were more in the coinfection group in comparison to dengue and scrub mono-infection.

CONCLUSIONS

Mono and coinfection of Dengue, Scrub typhus present with common clinical symptoms, laboratory findings. With limited resources for screening and diagnosis, clinical prediction based on symptoms alone or together with lab parameters is difficult which is further difficult in the presence of Co-infection.

CRISPR/Cas12a-Based Detection Platform for Early and Rapid Diagnosis of Scrub Typhus

Orientia tsutsugamushi is responsible for causing scrub typhus (ST) and is the leading cause of acute encephalitis syndrome (AES) in AES patients. A rapid and sensitive method to detect scrub typhus on-site is essential for the timely deployment of control measures. In the current study, we developed a rapid, sensitive, and instrument-free lateral flow assay (LFA) detection method based on CRISPR/Cas12a technology for diagnosing ST (named LoCIST). The method is completed in three steps: first, harnessing the ability of recombinase polymerase for isothermal amplification of the target gene; second, CRISPR/Cas12a-based recognition of the target; and third, end-point detection by LFA. The detection limit of LoCIST was found to be one gene copy of ST genomic DNA per reaction, and the process was complete within an hour. In 81 clinical samples, the assay showed no cross-reactivity with other rickettsial DNA and was 100% consistent with PCR detection of ST. LoCIST demonstrated 97.6% sensitivity and 100% specificity. Overall, the LoCIST offers a novel alternative for the portable, simple, sensitive, and specific detection of ST, and it may help prevent and control AES outbreaks due to ST. In conclusion, LoCIST does not require specialized equipment and poses a potential for future applications as a point-of-care diagnostic.

Prevalence of and factors associated with scrub typhus exposure among the hill tribe population living in high incidence areas in Thailand: a cross-sectional study

BACKGROUND

Scrub typhus is a significant tropical disease, occurring in rural settings and therefore usually afflicting remote agricultural populations who have lower socioeconomic status and limited access to medical care. A large proportion of the hill tribe people in Thailand are financially poor, have limited education, and do not have adequate health care access. This study aimed to estimate the prevalence of and determine factors associated with scrub typhus exposure among the hill tribe population living in high-incidence areas in northern Thailand.

METHODS

A cross-sectional study design was used to gather information from hill tribe people aged 18 years and over living in ten hill tribe villages in Mae Fah Luang, Chiang Rai Province, Thailand. Participants who met the inclusion criteria were invited to participate in the study. A validated questionnaire was used as the research instrument, and 5 mL blood samples were taken. Orientia tsutsugamushi IgM and IgG antibodies were detected by enzyme-linked immunosorbent assay (ELISA) and then confirmed by immunofluorescence assay (IFA). Logistic regression was used to detect associations between variables at a significance level of α = 0.05.

RESULTS

A total of 485 hill tribe people participated in the study; 57.1% were female, 29.9% were over 60 years of age, 46.4% were from the Akha tribe, and 74.2% had never attended school. The overall prevalence of scrub typhus exposure was 48.0%. In the multivariate model, five variables were found to be associated with scrub typhus exposure. Participants aged over 60 years had a 4.31-fold increased risk (95% CI = 1.73-10.72) of scrub typhus exposure compared to those who were younger than 30 years. Those who were illiterate had a 3.46-fold increased risk (95% CI = 1.93-6.21) of scrub typhus exposure than those who had at least a primary education level. Participants from the Akha tribe had a 2.20-fold increased risk (95% CI = 1.31-3.72) of scrub typhus exposure than those from the Lahu tribe. Subjects who had a history of cutting grass had a 1.85-fold increased risk (95% CI = 1.20-2.84) of scrub typhus exposure. Those who never wore gloves for farming had a 2.12-fold increased risk (95% CI = 1.28-3.49) of scrub typhus exposure than those who wore gloves daily.

CONCLUSIONS

There is a high prevalence of scrub typhus exposure among the hill tribe in Thailand. Effective public health interventions to promote scrub typhus awareness and prevention are urgently needed in these populations.

Clinical Characteristics and Diagnostic Prediction of Severe Fever with Thrombocytopenia Syndrome and Rickettsiosis in the Co-Endemic Wakayama Prefecture, Japan

Background and Objectives: The Wakayama prefecture is endemic for two types of tick-borne rickettsioses: Japanese spotted fever (JFS) and scrub typhus (ST). Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne hemorrhagic viral disease with a high mortality rate and is often difficult to differentiate from such rickettsioses. SFTS cases have recently increased in Wakayama prefecture. For early diagnosis, this study aimed to evaluate the clinical characterization of such tick-borne infections in the co-endemic area. Materials and Methods: The study included 64 febrile patients diagnosed with tick-borne infection in Wakayama prefecture between January 2013 and May 2022. Medical records of 19 patients with SFTS and 45 with rickettsiosis (JSF, n = 26; ST, n = 19) were retrospectively examined. The receiver operating curve (ROC) and area under the curve (AUC) were calculated to evaluate potential factors for differentiating SFTS from rickettsiosis. Results: Adults aged ≥70 years were most vulnerable to tick-borne infections (median, 75.5 years; interquartile range, 68.5-84 years). SFTS and rickettsiosis occurred mostly between summer and autumn. However, no significant between-group differences were found in age, sex, and comorbidities; 17 (89%) patients with SFTS, but none of those with rickettsiosis, experienced gastrointestinal symptoms such as vomiting, abdominal pain, and diarrhea. Meanwhile, 43 (96%) patients with rickettsiosis, but none of those with SFTS, developed a skin rash. The AUCs of white blood cells (0.97) and C-reactive protein (CRP) levels (0.98) were very high. Furthermore, the differential diagnosis of SFTS was significantly associated with the presence of gastrointestinal symptoms (AUC 0.95), the absence of a skin rash (AUC 0.98), leukopenia <3.7 × 109/L (AUC 0.95), and low CRP levels < 1.66 mg/dL (AUC 0.98) (p < 0.001 for each factor). Conclusions: Clinical characteristics and standard laboratory parameters can verify the early diagnosis of SFTS in areas where tick-borne infections are endemic.

A CARE-compliant article: A case report of unusual eschar and extensive soft tissue necrosis in Tsutsugamushi disease

RATIONALE

Tsutsugamushi disease is a common infectious disease in the Northern Hemisphere. A patient infected with tsutsugamushi disease will show a characteristic clinical course with eschar formation, which is mostly small and self-limited in nature without causing major problems. We report a rare case of unusually extensive necrosis started from a small eschar.

PATIENT CONCERNS

In this report, a 65-year-old female patient with a history of diabetes mellitus present an 8 × 6 cm-sized huge eschar and extensive soft tissue necrosis aggravated from a small eschar. Also, there were 3 other small eschars in the scalp and left flank area. In early July, she was farming in a field in Hongseong-gun, South Korea. She had been treated at another hospital for 2 weeks. However, the eschar became bigger and worse.

DIAGNOSES

After admission, escharectomy was performed and extensive soft tissue necrosis was identified. Orientia tsutsugamushi antibody tests were positive from blood test. Providencia rettgeri and Enterococcus faecalis were detected in a tissue bacterial culture test.

INTERVENTION

While using oral azithromycin and intravenous imipenem/cilastatin, the necrosis of the thigh was excised and covered by lateral femoral circumflex artery based myocutaneous Keystone flap.

OUTCOMES

The remaining small eschars recovered spontaneously, the large eschars that had caused necrosis were successfully treated, and all other clinical symptoms improved without complications.

LESSONS

For unusual eschar of an unknown cause, especially in patients with uncontrolled diabetes or immunocompromised, the possibility of Tsutsugamushi should be considered. Careful physical examination and proper management should be performed as soon as possible.

Molecular characterization of Orientia tsutsugamushi causing fatal scrub typhus in a young male affected by so-called "mystery fever" in North India

Scrub typhus is a zoonotic disease caused by Orientia tsutsugamushi. Although the presence of eschar is considered pathognomic, diagnosis of scrub typhus is challenging due to overlapping presentation. The diagnosis is based on the serological and molecular assay. Here, we describe a case of a young male patient who was diagnosed with scrub typhus and developed complications in the course of the disease. We also performed molecular characterization of the strain which revealed a close relatedness to Karp-like Linh.DT strains were previously reported from Vietnam.

Epidemiology of scrub typhus and other rickettsial infections (2018-22) in the hyper-endemic setting of Mizoram, North-East India

BACKGROUND

In the past decade, scrub typhus cases have been reported across India, even in regions that had no previous history of the disease. In the North-East Indian state of Mizoram, scrub typhus cases were first recorded only in 2012. However, in the last five years, the state has seen a substantial increase in the scrub typhus and other rickettsial infections. As part of the public health response, the Mizoram Government has integrated screening and line listing of scrub typhus and other rickettsial infections across all its health settings, a first in India. Here we detail the epidemiology of scrub typhus and other rickettsial infections from 2018-2022, systematically recorded across the state of Mizoram.

METHODOLOGY/PRINCIPAL FINDINGS

The line-listed data positive for scrub typhus and other rickettsial infections identified by rapid immunochromatographic test and/or Weil-Felix test from 2018-22 was used for the analysis. During this period, 22,914 cases of rickettsial infections were recorded, out of which 19,651 were scrub typhus cases. Aizawl is the worst affected, with 10,580 cases (46.17%). The average incidence of rickettsial infections is 3.54 cases per 1000 persons-year, and the case fatality rate is 0.35. Only ∼2% of the reported scrub typhus cases had eschar. Multivariate logistic regression analysis indicate patients with eschar (aOR = 2.5, p<0.05), occupational workers [farmers (aOR:3.9), businessmen (aOR:1.8), construction workers (aOR:17.9); p<0.05], and children (≤10 years) (aOR = 5.4, p<0.05) have higher odds of death due to rickettsial infections.

CONCLUSION

The integration of systematic surveillance and recording of rickettsial diseases across Mizoram has shed important insights into their prevalence, morbidity, and mortality. This study underscores the importance of active surveillance of rickettsial infections across India, as the burden could be substantially higher, and is probably going undetected.

Isothermal amplification technology (IAT) for rapid diagnosis of Rickettsioses: scope, overview, existing evidence, and the way forward

Rickettsioses, a category of zoonosis primarily caused by Rickettsia and Orientia, is a huge cause of public health concern worldwide. Diseases like murine typhus, scrub typhus, Mediterranean spotted fever and rocky mountain spotted fever are major contributors of Rickettsioses globally, with peculiar distributions in south-east Asia, Africa, Arabia and the Americas. With the innovations in molecular diagnostics, Isothermal Amplification Technology is gaining popularity for its fidelity, rapidity and cost-effectiveness. Compared to commercial assays, they are easily adaptable for point-of-care (PoC) settings. Due to nonspecific presentation as an acute undifferentiated febrile illness, diagnosis of Rickettsioses poses a great challenge. Certain isothermal amplification assays have proven to be highly efficient in diagnosing vector borne diseases like dengue, malaria, and chikungunya. The purpose of this review is to provide readers the current advancements, scope, challenges, and future prospects of isothermal amplification technologies in the detection of zoonotic pathogens like Rickettsia and Orientia.

Identification of novel variants for complicating cardiac disease in the scrub typhus infection using whole genome sequencing

BACKGROUND/AIMS

Scrub typhus infection has been known to complicate cardiovascular diseases mainly attributing to high mortality. Genetic susceptibility loci for complicating cardiac diseases such as atrial fibrillation, heart failure, and ischemic heart disease identified by genomic study have been limited in scrub typhus infection. Therefore, we investigated the genetic novel variants predicting complicating cardiac diseases in patients with confirmed scrub typhus infection using whole genome sequencing.

METHODS

We performed a prospective study for eight consecutive patients with scrub typhus infection. During follow-up, six cases were clinically diagnosed with complicating cardiac diseases and two controls without complicating cardiac diseases. The whole genomes of the all patients were sequenced, and the individual sequence variants were compared between accordcase and control patients. Variant genotypes were compared and identified as a single nucleotide polymorphism (SNP) of the different genotype distributions between six cases and two controls.

RESULTS

The GG genotype in SNP (rs4977397) of solute carrier 24 family member 2 (SLC24A2) gene and non-TT genotype in SNP (rs2676750) of adenosine deaminase, RNA specific, B2 (ADARB2) gene were distinctively found in the case patients with complicated cardiac disease, compared with control patents in the scrub typhus infection.

CONCLUSION

We suggest that the SNPs of SLC24A2 and ADARB2 might be genetic surrogate markers for complicating cardiac diseases in the scrub typhus infection. Our study show that early detection based on individual sequence variants might be feasible to predict complicating cardiac diseases in patients with scrub typhus infection, if further studies with more participants confirm these findings.

Clinical treatment of patients with scrub typhus-induced liver injury and intracranial infection

Scrub typhus is an infectious disease caused by Orientia tsutsugamushi, a bacterium within the family Rickettsiaceae. The clinical symptoms are usually acute and are characterized by fever, eschar formation or ulceration, local or generalized lymphadenopathy, and rash. Because of the extensive damage to small blood vessels throughout the body, scrub typhus can involve multiple systems and organs, causing damage to the respiratory, digestive, and nervous systems and inducing kidney and liver dysfunction. Death can occur in severe cases. We herein report two cases of scrub typhus with liver damage and intracranial infection. Among patients with scrub typhus, the risk of death is significantly higher in those who develop liver injury and intracranial infection. However, there are few reports on the treatment of patients with liver injury and intracranial infection caused by scrub typhus, and relevant treatment experience is thus lacking. Our clinical case report helps to fill the knowledge gap in this area.

Three cases of scrub typhus with hemorrhage: a case report and literature review

Scrub typhus (ST) is an acute focal infectious disease that is caused by Orientia tsutsugamushi. The Asia-Pacific region is an area of relatively high incidence. There is a high incidence in China, principally owing to the disease being endemic in the south of the country. The main source of ST infection is rats, which act as reservoirs of infection after being bitten by the chigger mite, and the human population is generally susceptible to the disease. ST can be controlled and treated successfully if antibiotics are administered in a timely manner. However, because it does not have a specific clinical manifestation, it is difficult to distinguish ST from other febrile diseases in clinical practice. Therefore, rapid diagnostic methods are still needed to help clinicians make a timely diagnosis. Here, we share three cases of patients with ST who experienced hemorrhage, but did not have typical skin lesions, such as eschar and ulcer, early in the course of their disease, and review the relevant literature regarding ST. We conclude that clinicians should pay attention to the risk of hemorrhage associated with this disease, and emphasize the importance of making an early diagnosis.

An alarming surge of scrub typhus cases presenting as acute encephalitis in children

Scrub typhus, which is prevalent in the Asia Pacific region is most feared owing to its life-threatening neurological complications. We present four cases of scrub typhus with acute encephalitis, including one with multiorgan failure and another serologically proven co-infection with Hepatitis C. Treatment of scrub typhus is not, however, so difficult, so its early diagnosis is paramount.

Retrospective analysis of clinico-laboratory parameters, outcome and predictors of scrub typhus co- infection in covid-19 affected children

The objective of this study was to describe clinico-laboratory parameters, outcome and predictors of scrub typhus co- infection in COVID-19 affected children. Ours was a retrospective analysis done in a tertiary care pediatric COVID facility. COVID-19 positive children in the age group of 1 month to 12 years who were tested for scrub typhus co-infection between May to August 2020 were included in the study. In all positive cases, clinical, laboratory, treatment and outcome data were analyzed. Relevant data were compared between scrub typhus confirmed, and suspected but negative patients. All six patients with co-infection had fever for >5 days and four had features of cerebral involvement. These had lymphocytic pleocytosis in cerebrospinal fluid (CSF) analysis and two had eschar. Screening for scrub typhus in persistently febrile children residing in highly endemic areas is highly recommended.

The first case report of acute myocardial infarction in young adult caused by scrub typhus

RATIONALE

Scrub typhus is a zoonotic disease caused by Orientia tsutsugamushi, a gram-negative intracellular bacterium and endemic in Asia-Pacific area. Acute myocardial infarction after Oricntia tsutsugamushi infection was rarely reported, and young adult was not reported.

PATIENT CONERNS

A 33-year-old man came to the emergency complained with chest tightness and fever for 4 days.

DIAGONOSES

After Weil-Felix agglutination test (titer 1:160) twice, scrub typhus was diagnosed.

INTERVENTIONS

After treating with a hormonotherapy, antibiotic and ventilator-assisted ventilation, his chest tightness was mild lessened with normal breath and body temperature. However, an emergent coronary angiography performed unnormal, then a percutaneous coronary intervention was realized with the implantation of a stent.

OUTCOMES

After the surgeon, his chest tightness was totally released, and he was discharged.

LESSONS

Our case was the first report of young adult acute myocardial infarction after O tsutsugamushi infection and we tried to figure out the potential mechanism and how to deal with.

A case of pulmonary tuberculosis patient complicated with hemorrhagic fever with renal syndrome and scrub typhus in Yunnan, China: a case report

BACKGROUND

Hemorrhagic fever with renal syndrome (HFRS) caused by Orthohantavirus (OHV) and scrub typhus (ST) caused by Orientia tsutsugamushi (OT) are two infectious diseases prevalent in southwest China. Rodents are the natural host and the main source of the two diseases. OT infection to humans is usually resulted from bite of an infective chigger mite on rodents, and OHV is transmitted through contact or inhalation of aerosols and secretions from infected rodent. The use of antibiotics and hormones is crucial for infectious diseases, although the clinical manifestations are not obvious and a definitive diagnosis becomes more difficult in the presence of these drugs. Clinically, fever is the first symptom of these two diseases, and most of them are accompanied by common symptoms such as chills and headaches. The clinical symptoms of these two diseases are very similar and therefore it is not easy to make a differential diagnosis.

CASE PRESENTATION

In this case, a 44-year-old male famer with pulmonary tuberculosis and a history of working in coal transportation was admitted to the hospital because of respiratory symptoms accompanied by fever, headache, and skin rashes on his body. Biochemical and urinalysis revealed the hepatic and renal injury. The subsequent molecular testing confirmed he suffered from HFRS and scrub typhus simultaneously that the serological and clinical diagnosis could not identify the cause of infection before. Such case has not been reported in Yunnan Province before.

CONCLUSION

The clinical diagnosis should be combined with serological and nucleic acid testing approaches for differential diagnosis in areas where HFRS and ST are endemic.

Historical epidemics of scrub typhus in Queensland and Papua New Guinea

Undifferentiated febrile diseases (e.g., Mossman fever) from northern Queensland were eventually partially attributed to mite-transmitted rickettsial infections known as scrub typhus or tsutsugamushi fever. Scrub typhus became a major medical threat to military operations in Papua New Guinea during the Second World War and killed more Australian soldiers than malaria in the pre-antibiotic era. Further investigations showed scrub typhus to be an occupational disease of rural workers in north Queensland especially around Cairns and Innisfail. Occasional small epidemics of scrub typhus still occur during military exercises in Queensland, but as scrub typhus is not a reportable disease, its presence in the civilian community is largely unknown. Increased use of serological testing in patients with fever and rash illnesses after exposure in northern Queensland is likely to show that scrub typhus is a modern infection that remains treatable with antibiotics once it is identified.

Re: Leukocytoclastic Vasculitis: A peculiar presentation of scrub typhus

NONE

Diagnostic Accuracy of Rapid Antibody Detection Test for Scrub Typhus

OBJECTIVE

To detect the diagnostic accuracy of rapid antibody detection test using IgM immunochromatography for scrub typhus in children.

METHODS

This cross-sectional study enrolled children aged 2 months-18 years hospitalized over a period of 18 months with undifferentiated fever of duration five days or more. The blood samples were subjected to serological tests like Weil-Felix, Scrub IgM ELISA, immunofluroscence assay (IFA) and rapid diagnostic test (IgM Immunochromatography). Diagnostic accuracy was measured against IFA as the gold standard.

RESULTS

A total of 90 children were included in the study, among which 43 children were positive for gold standard test IFA. Rapid diagnostic test showed sensitivity of 88.3%, specificity of 89.3%, positive predictive value of 88.3% and negative predictive value of 89.3%. The sensitivity, specificity, PPV and NPV of Weil-Felix test was 39.5%, 84.2%, 58.6 and 71.1%, respectively and of IgM ELISA was 93%, 89.3%,88.8% and 93.3%, respectively.

CONCLUSION

IgM immunochromatography had good diagnostic accuracy for scrub typhus in children with acute undifferentiated fever.

Diagnostic Accuracy of Rapid Antibody Detection Test for Scrub Typhus

OBJECTIVE

To detect the diagnostic accuracy of rapid antibody detection test using IgM immunochromatography for scrub typhus in children.

METHODS

This cross-sectional study enrolled children aged 2 months-18 years hospitalized over a period of 18 months with undifferentiated fever of duration five days or more. The blood samples were subjected to serological tests like Weil-Felix, Scrub IgM ELISA, immunofluroscence assay (IFA) and rapid diagnostic test (IgM Immunochromatography). Diagnostic accuracy was measured against IFA as the gold standard.

RESULTS

A total of 90 children were included in the study, among which 43 children were positive for gold standard test IFA. Rapid diagnostic test showed sensitivity of 88.3%, specificity of 89.3%, positive predictive value of 88.3% and negative predictive value of 89.3%. The sensitivity, specificity, PPV and NPV of Weil-Felix test was 39.5%, 84.2%, 58.6 and 71.1%, respectively and of IgM ELISA was 93%, 89.3%,88.8% and 93.3%, respectively.

CONCLUSION

IgM immunochromatography had good diagnostic accuracy for scrub typhus in children with acute undifferentiated fever.

Edifications on Indirect IgM ELISA and Immunofluorescence assay (IFA) of scrub typhus in humans and erudition of Orientia tsutsugamushi in the vector of cohabiting rodents

Scrub typhus is a vector-borne disease caused by Orientia tsutsugamushi, propagated into humans by the bite of infected mite belonging to genus Leptotrombodium. The present study was conducted in the Nagpur region of central India aiming towards a survey of cohabiting rodents and their potential vectors for the presence of Orientia tsutsugamushi by PCR method. The study also emphasizes serological diagnosis of the disease by employing indirect IgM ELISA and IFA amongst the human cases of pyrexia of unknown origin. Indirect IgM ELISA recorded 39.69% (31/92) seropositive patients, further processing of ELISA positive samples for IFA revealed 67.74 % (21/31) positivity for Boryong, Gilliam, Karp, and Kato serotypes. A total of 50 rodents were trapped from the cohabit areas of the patients. Three different types of rodents were identified; among which, Rattus bandicoot was highest. From these rodents, 164 vectors viz mites, lice, and fleas were collected. The highest chiggar index was recorded for Ornithonyssus biscotti mites (3.4). This study prompts a detailed analysis of different species of rodents and vectors in the said endemic region.

Seroprevalence of Rickettsial disease: A population-based survey from kashmir valley, North India

Background

Limited studies have been done regarding the prevalence of Rickettsial diseases in India and as far as UT of Jammu and Kashmir is concerned, only a few hospital-based studies are available.

Objectives

The present study was therefore planned to find the seroprevalence of Rickettsial diseases in Kashmir Valley.

Materials and Methods

A multistage sampling procedure was used for the collection of samples from 10 districts of Kashmir Valley and a total of 1740 samples were collected. In addition, 802 healthy blood donors were included to establish baseline titers for Weil-Felix (WF) Test.

Results

Of 1734 subjects, 73 were positive by the WF test. The overall seroprevalence of Rickettsial diseases was 4.1% with the highest prevalence of scrub typhus (2.30%) followed by the spotted fever group (1.5%) and typhus group (0.40%). Maximum seropositive subjects were from district Kulgam (6.97%) followed by Pulwama (5.92%), Shopian (5.79%), Anantnag (5.47%), Ganderbal (5.00%), Kupwara (4.72%), Baramulla (4.62%), Srinagar (2.63%), Bandipora (2.41%), and Budgam (0.54%), respectively. Seropositivity was higher in females and subjects who had contact with ticks and mites like those involved in the collection of firewood and grass or had contact with uncut grass or shrub. The seropositivity was also significantly higher in those working in paddy fields and those living near the forest (P < 0.05).

Conclusion

The results of the present study confirm the existence of Rickettsial diseases in this region. This data would promote awareness of rickettsioses among local physicians and will also serve as a baseline to detect changing prevalence in the future.

Scrub typus fulminating as liver failure: A rare report

Scrub typhus is almost an endemic tropical mite-borne, zoonotic illness often cognate with the bacterium Orientia tsutsugamushi. After a typical incubation period of a fortnight, non-specific symptoms including fever, headache, and a specific skin 'eschar' is customary. If untreated after a symptomatic week, scrub typus may precipitate end-organ involvements spiraling into vivid complications. Nevertheless, crub typhus tends to display mild transaminitis, frank liver failure is hardly common in clinical practice. An instance of scrub typus triggering fulminant hepatic failure (FHF) in a middle-aged female is being reported here.

Costs & outcomes of hospitalized scrub typhus infection in a tertiary hospital in south India

Background & objectives

Scrub typhus is a rickettsial infection seen along the Asian-Pacific rim and imposes a considerable burden on affected people in low- and middle-income countries. The present study was aimed to determine the direct cost of hospitalization of scrub typhus and its trend over six years.

Methods

This was a retrospective, observational, hospital based study of individuals admitted to the hospital, diagnosed with scrub typhus over six years, from January 2013 to December 2018. The potential out of pocket expenditure was evaluated.

Results

A total of 198 patients were included in the study. The median cost of admission (adjusted to INR 2020) for the six years (2013 to 2018) was found to be ₹ 37,026 (US $ 490) [interquartile range (IQR) 22,996-64,992]. The median cost for patients admitted to the intensive care unit (ICU) was ₹ 128,046 (US $ 1695) (IQR 71,575-201,171), while the cost for patients admitted to the ward-alone was ₹ 33,232 (US $ 440) (IQR 19,609-45,373). The multivariable analysis showed that ARDS and SOFA score were the independent predictors of ICU admission.

Interpretation & conclusions

Hospitalisation for scrub typhus is associated with a substantial healthcare expense. The predictors of increased cost were the presence of acute respiratory distress syndrome (ARDS), shock, increasing sequential organ failure assessment (SOFA) score and duration of hospital stay.

Clinical profile and outcomes of pediatric scrub typhus associated with elevated hepatic transaminases

BACKGROUND

Hepatic transaminase (HT) elevation is frequently seen in children with scrub typhus (ST), but the clinical implication of this common finding is not known.

OBJECTIVE

To describe the clinical profile and outcome of pediatric ST with elevated hepatic transaminase.

METHODS

In this prospective cohort study, all children < 12 years of age presenting with fever for ≥ 5 days and positive immunoglobulin M (IgM) serology for ST were included. Clinical findings, laboratory features and outcomes of children with elevated HT were compared with those who had normal HT.

RESULTS

Of 560 ST positive children included, 257 (45.8%) had associated HT elevation. The common age group affected was 5 to 12 years of age (54.9%). Most of the children came during the second week of fever (68.5%) with mean duration of fever of 9.1 days. The common initial presenting symptoms were cough (77.8%), vomiting (65%) and myalgia (59.1%) and signs were hepatomegaly (64.2%), splenomegaly (57.6%) and generalized lymphadenopathy (54.1%). Eschar was seen in 49.8% of children. Thrombocytopenia (58%) and anemia (49%) were the frequently seen laboratory abnormalities. Severe forms of ST were seen in 45.5% children, of which pneumonia was most common. The fever clearance time (48 ± 19.2 h) and mean duration of hospital stay (6.7 ± 3.3 days) were prolonged in these children. On logistic regression analysis, generalized lymphadenopathy (p = 0.002), ascites (p = 0.037), thrombocytopenia (p < 0.001) and hypoalbuminemia (p = 0.023) were found to be associated with HT elevation in these children.

CONCLUSIONS

Hepatic transaminase (HT) levels increase with the duration of untreated fever and is found to be associated with severe forms of scrub typhus. Children with elevated HT have delay in fever defervescence and their duration of hospital stay was prolonged.

Determination of a cut-off value for the serological diagnosis of scrub typhus by detecting anti-Orientia tsutsugamushi immunoglobulin M

Background & objectives

The diagnosis of scrub typhus (ST) is usually done using enzyme-linked immunosorbent assay (ELISA) due to its ease of performance and reading objectivity. The cut-off value for ELISA needs to be calculated for each geographical location as it depends on zonal endemicity of the disease. This study was, therefore, undertaken to calculate the pan-India cut-off for anti-Orientia tsutsugamushi (OT) immunoglobulin M (IgM) by ELISA.

Methods

Samples from cases (cases of ST) and controls (voluntary, consenting, healthy adults) were collected by a network of 29 laboratories across India and tested for anti-OT IgM by immunofluorescence assay (IFA), the considered gold standard test. These samples were retested by ELISA for anti-OT IgM and their optical densities (ODs) were used for cut-off estimation by receiver operating characteristic (ROC) curve.

Results

Anti-OT IgM ELISA ODs from 273 controls and 136 cases were used for the cut-off estimation. The ODs of the anti-OT IgM ELISA on healthy individuals and those of confirmed ST cases ranged from 0.1 to 0.75 and 0.5 to 4.718, respectively. ROC curve-based cut-off for ELISA was calculated as 0.554 at a sensitivity of 95.2 per cent and specificity of 95.1 per cent. A value of >1 was noted to have a specificity of 100 per cent in diagnosing ST.

Interpretation & conclusions

The cut-off calculated for India was similar to the previous cut-off that was used until now.

Environmental, Occupational, and Demographic Risk Factors for Clinical Scrub Typhus, Bhutan

Underdiagnosis and underreporting of scrub typhus has increasingly affected public health in Bhutan since its initial detection in 2008. Identifying scrub typhus risk factors would support early diagnosis and treatment for this nonspecific febrile disease, reducing the incidence of potentially fatal complications. We conducted a hospital-based, case‒control study during October‒December 2015 in 11 scrub typhus‒prone districts. We identified harvesting cardamom as the major risk factor (odds ratio 1,519; p<0.001); other factors were traditional housing, largely caused by an outside toilet location, as well as owning a goat and frequently sitting on grass. Harvesting vegetables, herding cattle in the forest, and female sex were protective. Age had a nonlinear effect; children and the elderly were more likely to seek treatment for clinical scrub typhus. This study has informed public health policies and awareness programs for healthcare workers through development of National Guidelines for Prevention, Treatment and Control of Scrub Typhus in Bhutan.

HLA-B27 Negative Reactive Monoarthritis of the Hip Joint Triggered by Scrub Typhus: A Case Report

Scrub typhus is common in rural Nepal's southern plains, but its diagnosis remains difficult due to a lack of clinical suspicion and poor diagnostic resources. The absence of common manifestations of the condition including eschar might further complicate this problem and may result in treatment delays. We report a case of scrub typhus with the primary presentation of reactive monoarthritis of the left hip joint in a 19-year-old male who presented with difficulty in walking, and pain over the left hip joint. Ultrasonography of the left hip and thigh showed features of synovitis and iliopsoas bursitis. After a meticulous workup, a diagnosis of human leukocyte antigen B27 negative reactive monoarthritis of the left hip joint triggered by scrub typhus infection was made and the patient was treated with doxycycline. Delays in treatment and the rate of complications can be prevented with high clinical suspicion and awareness of the atypical presentation of the condition.

Keywords

HLA-B27; case reports; reactive arthritis; scrub typhus.