Antibiotics for treating scrub typhus

The economic burden of scrub typhus disease among the tribal ethnic groups (Mizo) of Mizoram State, Northeast India

BACKGROUND

Orientia tsutsugamushi is the pathogen of scrub typhus, a rickettsial infection that poses a serious threat to many countries including India where the disease case-fatality was as high as 6%. The present study was aimed at determining the prevalence of scrub typhus disease and estimating the economic impact of the disease among the Mizo tribe of Mizoram State, Northeast India.

MATERIALS & METHODS

The present study was a three-year retrospective, cross-sectional study conducted in 10 selected PHCs of Mizoram. The line-listing data of three years (2021-2023) on scrub typhus was used for the epidemiological investigation. The minimum economic burden of scrub typhus was evaluated using data collected by personal interviews with the scrub typhus survivors among the Mizo tribe.

RESULTS

A total of 22870 scrub typhus cases were recorded among the tribal ethnic groups (Mizo) in Mizoram State in the year 2021-2023, with an annual incidence of 571.48 per 100,000 persons. A positive relationship between age and disease incidence was observed, with a higher burden (1964.5 per 100,000 persons) among the elderly population (70 + years). The disease incidence rate also showed increasing trend and seasonality, with the peak of cases during August-October. The overall three years economic burden was found to be US$ 730,003.80, with an average annual economic burden of US$ 243,334.60 contributing 0.08% of the gross state domestic product (GSDP). An increasing trend in scrub typhus economic burden was observed during the study period.

CONCLUSIONS

According to the current study, Mizoram State's tribal ethnic groups have a remarkably high incidence rate of scrub typhus disease causing a significant financial impact. Therefore, prevention and control measures for the disease are unavoidable.

Scrub Typhus Mimicking Severe Community-Acquired Pneumonia: A Diagnostic Challenge

A 23-year-old previously healthy female presented with a five-day history of high-grade fever, productive cough, throat pain, and progressive breathlessness. On admission, she was in respiratory distress with severe hypoxia requiring high-flow nasal cannula support. Chest x-ray revealed extensive bilateral lower lobe consolidation, moderate left-sided pleural effusion, and right-sided minimal pleural effusion. Initial empirical treatment with ceftriaxone and azithromycin for community-acquired pneumonia failed to improve her condition. High-resolution computed tomography of the chest confirmed multilobar consolidation, prompting further infectious workup. Serology for scrub typhus was positive, leading to a diagnosis of scrub typhus pneumonia. The patient was transitioned to targeted therapy with doxycycline, resulting in rapid clinical improvement. Oxygenation improved, inflammatory markers declined, and she was successfully weaned off non-invasive ventilation. However, she developed persistent hoarseness, and laryngoscopic evaluation revealed post-infectious laryngitis with reduced vocal cord mobility. The condition was managed conservatively with voice rest and steam inhalation, leading to gradual resolution. She was discharged after 14 days with complete respiratory recovery. Scrub typhus pneumonia typically involves the lower lobes, but multilobar involvement, upper lobe consolidation, and pleural effusion are rare. Delayed diagnosis and the absence of a characteristic eschar can contribute to treatment delays. Early suspicion, serological testing, and initiation of doxycycline are essential for favorable outcomes. Our case highlights the need to consider scrub typhus in patients with severe, atypical pneumonia, particularly in endemic regions.

Scrub typhus associated with reactive arthritis: A case report and literature review

Scrub typhus (tsutsugamushi disease) is an acute febrile illness caused by Orientia tsutsugamushi, often found in Asia and Oceania. The presence of an eschar, characterized by a crust, is a key diagnostic finding. Many symptoms of this disease are already known, however reactive arthritis following scrub typhus is very rare. Here, we present a case of 79-year-old man who was referred to our hospital because of continuous fever and left shoulder pain. We found 4-fold rise in Orientia tsutugamushi-specific IgG titer using paired serum samples and Orientia sp. genes by real-time PCR from a crust of right thigh. And the left shoulder joint image was consistent with aseptic arthritis; thus we diagnosed as scrub typhus with reactive arthritis. This case highlights the importance of recognizing reactive arthritis as a symptom of scrub typhus. In this report, we also review published cases of reactive arthritis associated with scrub typhus, and we suppose that this arthritis related to this infection may recover after antibiotic use and have a good prognosis. Physicians' awareness of newly appeared arthritis may contribute to facilitate early diagnosis, and may improve the course of such patients.

Omadacycline in the treatment of scrub typhus: Three case reports

BACKGROUND

Scrub typhus is a naturally occurring acute infectious disease that is primarily transmitted through the bites of chiggers or larval mites infected by Orientia tsutsugamushi (O. tsutsugamushi). Omadacycline, a novel tetracycline, exhibits potent antibacterial efficacy against both typical bacteria and atypical pathogens. However, omadacycline application in the treatment of scrub typhus remains limited.

CASE SUMMARY

In the present work, we report several cases of scrub typhus, with the main clinical symptoms being fever, the formation of eschars or ulcers, local or systemic lymphadenopathy, headache, myalgia and rash. Blood samples were collected before omadacycline was administered, and O. tsutsugamushi infection was confirmed through targeted next-generation sequencing (tNGS). After two days of treatment, the patients' symptoms, including fever, were alleviated, with no adverse drug reactions.

CONCLUSION

tNGS is an effective method for diagnosing scrub typhus. Omadacycline can be considered an alternative option for antiinfective therapy in patients with O. tsutsugamushi infections.

Ocular inflammation in tsutsugamushi disease - a case report

A 64-year-old male, working at a mountain site in Taitung County, suffered from primary open angle glaucoma (POAG) post trabeculectomy with well-controlled intraocular pressure (IOP) in both eyes (OU). He presented with headache accompanied by red eyes (OU) for 10 days. Physical examination revealed fever up to 38.2°C, neck stiffness, one eschar at the left forearm and another at the left ankle. Abnormal laboratory data indicated bacterial infection with central nervous system involvement. Ophthalmic examination showed elevated IOP, moderate conjunctival congestion, subconjunctival hemorrhage, anterior uveitis, cotton-wool spots on the retina and multiple white dots on the temporal retina (OU). Under the impression of uveitis in tsutsugamushi disease with atypical meningitis, oral doxycycline, anti-glaucoma and anti-inflammation eye drugs were prescribed. IOP returned to 12 mmHg and anterior uveitis subsided. The lesions of cotton-wool spots on the retina disappeared within 2 weeks, but multiple white dots remained persistently on the temporal retina.

Microbial Degradation of Tetracycline Antibiotics: Mechanisms and Environmental Implications

The escalating global consumption of tetracyclines (TCs) as broad-spectrum antibiotics necessitates innovative approaches to mitigate their pervasive environmental persistence and associated risks. While initiatives such as China's antimicrobial reduction efforts highlight the urgency of responsible TC usage, the need for efficient degradation methods remains paramount. Microbial degradation emerges as a promising solution, offering novel insights into degradation pathways and mechanisms. Despite challenges, including the optimization of microbial activity conditions and the risk of antibiotic resistance development, microbial degradation showcases significant innovation in its cost-effectiveness, environmental friendliness, and simplicity of implementation compared to traditional degradation methods. While the published reviews have summarized some aspects of biodegradation of TCs, a systematic and comprehensive summary of all the TC biodegradation pathways, reactions, intermediates, and final products including ring-opening products involved with enzymes and mechanisms of each bacterium and fungus reported is necessary. This review aims to fill the current gap in the literature by offering a thorough and systematic overview of the structure, bioactivity mechanism, detection methods, microbial degradation pathways, and molecular mechanisms of all tetracycline antibiotics in various microorganisms. It comprehensively collects and analyzes data on the microbial degradation pathways, including bacteria and fungi, intermediate and final products, ring-opening products, product toxicity, and the degradation mechanisms for all tetracyclines. Additionally, it points out future directions for the discovery of degradation-related genes/enzymes and microbial resources that can effectively degrade tetracyclines. This review is expected to contribute to advancing knowledge in this field and promoting the development of sustainable remediation strategies for contaminated environments.

A Multi-epitope Subunit Vaccine Identification and Development Against Scrub Typhus (Orientia tsutsugamushi) Using Immunoinformatics Approaches

Background The pathogen Orientia tsutsugamushi, which causes scrub typhus, is rapidly spreading throughout the tropics. As a measure to improve public health, the development of a vaccine for human use is essential. Scrub typhus is listed as one of the underdiagnosed and underreported febrile infections. This vector-borne zoonotic infection appears as eschar on the patient's skin. Methods Immunoinformatics was employed to predict the multi-epitope subunit vaccine that will activate both B and T cells. The final vaccine includes lipoprotein LprA as an adjuvant at the N-terminus along with B-cell, helper T lymphocyte (HTL), and cytotoxic T lymphocyte (CTL)-binding epitopes to boost immunogenicity. Assessing the vaccine's physiochemistry demonstrates that it is both antigenic and non-allergic. The vaccine structure was developed, enhanced, confirmed, and disulfide-engineered to provide the best possible model. Using molecular docking, the interaction of the produced vaccine with toll-like receptor 2 (TLR2) was analyzed, and the vaccine-receptor complex was stabilized by molecular dynamics (MD) simulation. According to in silico cloning, Escherichia coli can efficiently produce the recommended vaccine. Additionally, the efficacy of the in silico-developed vaccine must be evaluated in an in vitro and in vivo experiment. Results The developed vaccine successfully stimulates cellular and humoral immune responses. The vaccine, which has three B-cell epitopes, three HCL epitopes, and nine CTL epitopes, can bind firmly to immunological receptors. Dynamic investigations of the vaccine-receptor complex show a strong interaction and stable conformation. Conclusion In this study, the vaccine candidate demonstrated strong antigenicity, stability, and solubility while also being non-allergenic to host cells. The vaccine candidate's stability with the TLR2 immune receptor is established by binding studies, and in silico cloning verifies efficient and stable expression in the bacterial system.

A proof of concept for a targeted enrichment approach to the simultaneous detection and characterization of rickettsial pathogens from clinical specimens

Infection with either Rickettsia prowazekii or Orientia tsutsugamushi is common, yet diagnostic capabilities are limited due to the short window for positive identification. Until now, although targeted enrichment had been applied to increase sensitivity of sequencing-based detection for various microorganisms, it had not been applied to sequencing of R. prowazekii in clinical samples. Additionally, hybridization-based targeted enrichment strategies had only scarcely been applied to qPCR of any pathogens in clinical samples. Therefore, we tested a targeted enrichment technique as a proof of concept and found that it dramatically reduced the limits of detection of these organisms by both qPCR and high throughput sequencing. The enrichment methodology was first tested in contrived clinical samples with known spiked-in concentrations of R. prowazekii and O. tsutsugamushi DNA. This method was also evaluated using clinical samples, resulting in the simultaneous identification and characterization of O. tsutsugamushi directly from clinical specimens taken from sepsis patients. We demonstrated that the targeted enrichment technique is helpful by lowering the limit of detection, not only when applied to sequencing, but also when applied to qPCR, suggesting the technique could be applied more broadly to include other assays and/or microbes for which there are limited diagnostic or detection modalities.

Concatenated ScaA and TSA56 Surface Antigen Sequences Reflect Genome-Scale Phylogeny of Orientia tsutsugamushi: An Analysis Including Two Genomes from Taiwan

Orientia tsutsugamushi is an obligate intracellular bacterium associated with trombiculid mites and is the causative agent of scrub typhus, a life-threatening febrile disease. Strain typing of O. tsutsugamushi is based on its immunodominant surface antigen, 56-kDa type-specific antigen (TSA56). However, TSA56 gene sequence-based phylogenetic analysis is only partially congruent with core genome-based phylogenetic analysis. Thus, this study investigated whether concatenated surface antigen sequences, including surface cell antigen (Sca) proteins, can reflect the genome-scale phylogeny of O. tsutsugamushi. Complete genomes were obtained for two common O. tsutsugamushi strains in Taiwan, TW-1 and TW-22, and the core genome/proteome was identified for 11 O. tsutsugamushi strains. Phylogenetic analysis was performed using maximum likelihood (ML) and neighbor-joining (NJ) methods, and the congruence between trees was assessed using a quartet similarity measure. Phylogenetic analysis based on 691 concatenated core protein sequences produced identical tree topologies with ML and NJ methods. Among TSA56 and core Sca proteins (ScaA, ScaC, ScaD, and ScaE), TSA56 trees were most similar to the core protein tree, and ScaA trees were the least similar. However, concatenated ScaA and TSA56 sequences produced trees that were highly similar to the core protein tree, the NJ tree being more similar. Strain-level characterization of O. tsutsugamushi may be improved by coanalyzing ScaA and TSA56 sequences, which are also important targets for their combined immunogenicity.

Case Report: Encephalitis with Initial Manifestation of Orientia Tsutsugamushi Infection Detected by Metagenomic Next-Generation Sequencing

Purpose

Scrub typhus, caused by Orientia tsutsugamushi, is characterized by fever, eschars, lymphadenopathy, and rash. The absence of eschars in some cases makes it difficult to distinguish it from other diseases, complicating the diagnosis process. Atypical Scrub typhus is difficult to diagnose and often leads to delayed treatment. Therefore, early diagnosis and treatment through effective detection methods have high clinical value. Here, a case of scrub typhus with encephalitis symptoms is reported.

Patients and Methods

A 64-year-old man and mNGS testing.

Results

A 64-year-old man developed cough, headache, and fever, dismissing it as a respiratory tract infection. Initial treatment with cephalosporin antibiotics had minimal effect. Admission to the respiratory department showed inflammation in blood tests. Subsequent CT and further treatment provided no improvement. Multidisciplinary discussions and neurology department guidance were conducted to consider the suspected diagnosis of encephalitis in the patient. After improving the mNGS detection, the patient was diagnosed with "Orientia tsutsugamushi encephalitis". After treatment with doxycycline, the patient's symptoms were alleviated. He remained afebrile in follow-up and adhered well to medical advice.

Conclusion

Our case demonstrates that it is difficult to distinguish Orientia tsutsugamushi encephalitis from central nervous system infectious diseases such as meningitis and encephalitis using conventional diagnostic methods, which may affect the treatment plan for the disease. mNGS is a useful and valuable method for early diagnosis of scrub typhus.

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.

Multifaceted realities of scrub typhus: a case series from southern India

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi, a Gram-negative bacillus, commonly occurring in the Asia-Pacific region. It is transmitted to humans by the bite of an infected Leptotrombidium mite and the bacterium causes endothelial dysfunction resulting in widespread vasculitis and the possible development of thrombocytopenia, meningitis, acute respiratory distress syndrome, and infrequently, myocarditis. Early diagnosis and prompt treatment are crucial in managing scrub typhus. Here, we present four cases of scrub typhus with a comprehensive literature review. This study highlights the significance of considering scrub typhus as a possible diagnosis in patients of all ages from endemic regions who exhibit symptoms such as fever, thrombocytopenia, or transaminitis, even in the absence of typical clinical features. Two cases exhibited the characteristic lesion of eschar at the site of mite feeding. One case involved a middle-aged woman who was diagnosed with typhus-induced myocarditis with left ventricular dysfunction. Another case involved a 23-day-old neonate with poor feeding and seizures, who was diagnosed with late-onset sepsis with meningitis. Scrub typhus was confirmed in all cases using a positive qualitative IgM ELISA. However, it is preferred to use paired (ELISA before and after antibiotic therapy) or quantitative titers for confirmation. Healthcare providers must consider the patient's exposure history and clinical presentation to diagnose and treat scrub typhus promptly.

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.

High prevalence of antimicrobial resistance and multidrug resistance among bacterial isolates from diseased pets: Retrospective laboratory data (2015-2017)

Laboratory surveillance and the monitoring of antimicrobial resistance (AMR) trends and patterns among local isolates have been highly effective in providing comprehensive information for public health decision-making. A total of 396 cases along with 449 specimens were received for antibiotic susceptibility testing at a public university veterinary diagnostic laboratory in Malaysia between 2015 and 2017. Escherichia coli was the most frequently isolated (n = 101, 13%) bacteria, followed by Staphylococcus pseudintermedius (n = 97, 12%) and Streptococcus canis (n = 62, 8%). In cats, S. pseudintermedius isolates were highly resistant to azithromycin (90%), while the E. coli isolates were highly resistant to doxycycline (90%), tetracycline (81%), and cephalexin (75%). About 55% of S. pseudintermedius and 82% of E. coli were multi-drug resistant (MDR). In dogs, S. intermedius isolates were highly resistant to aminoglycosides neomycin (90.9%) and gentamicin (84.6%), and tetracycline (75%). Whereas the E. coli isolates were highly resistant to cephalexin (82.1%) and amoxicillin/clavulanic acid (76.5%). MDR was observed in 60% of S. intermedius and 72% of E. coli from dogs. Generally, the bacterial isolates from cats demonstrated higher levels of resistance to multiple antibiotics compared to those from dogs.

Neurological manifestations of scrub typhus infection: A systematic review and meta-analysis of clinical features and case fatality

BACKGROUND

Scrub typhus has become a leading cause of central nervous system (CNS) infection in endemic regions. As a treatable condition, prompt recognition is vital. However, few studies have focused on describing the symptomology and outcomes of neurological scrub typhus infection. We conducted a systematic review and meta-analysis to report the clinical features and case fatality ratio (CFR) in patients with CNS scrub typhus infection.

METHODS

A search and analysis plan was published in PROSPERO [ID 328732]. A systematic search of PubMed and Scopus was performed and studies describing patients with CNS manifestations of proven scrub typhus infection were included. The outcomes studied were weighted pooled prevalence (WPP) of clinical features during illness and weighted CFR.

RESULTS

Nineteen studies with 1,221 (656 adults and 565 paediatric) patients were included. The most common clinical features in CNS scrub typhus were those consistent with non-specific acute encephalitis syndromes (AES), such as fever (WPP 100.0% [99.5%-100.0%, I2 = 47.8%]), altered sensorium (67.4% [54.9-78.8%, I2 = 93.3%]), headache (65.0% [51.5-77.6%, I2 = 95.1%]) and neck stiffness 56.6% (29.4-80.4%, I2 = 96.3%). Classical features of scrub typhus were infrequently identified; an eschar was found in only 20.8% (9.8%-34.3%, I2 = 95.4%) and lymphadenopathy in 24.1% (95% CI 11.8% - 38.9%, I2 = 87.8%). The pooled CFR (95% CI) was 3.6% (1.5%- 6.4%, I2 = 67.3%). Paediatric cohorts had a CFR of 6.1% (1.9-12.1%, I2 = 77%) whilst adult cohorts reported 2.6% (0.7-5.3%, I2 = 43%).

CONCLUSION

Our meta-analyses illustrate that 3.6% of patients with CNS manifestations of scrub typhus die. Clinicians should have a high index of suspicion for scrub typhus in patients presenting with AES in endemic regions and consider starting empiric treatment whilst awaiting results of investigations, even in the absence of classical signs such as an eschar or lymphadenopathy.

Scrub typhus presenting as cryptogenic organizing pneumonia in a young female: A first case report

We report the case of a young female suffering from fever and generalized weakness on presentation and was diagnosed to be a case of cryptogenic organizing pneumonia (COP). She developed breathlessness on rest and required oxygen support and on further evaluation diagnosed with Scrub typhus IgM positive status. This case report highlights the importance of a rare presentation of Scrub typhus in a young female presenting with clinically silent chest changes initially and preventable worse outcomes if detected and managed for scrub typhus infection early in the course of disease.

Scrub Typhus Meningoencephalitis: Review of Literature and Unique Diagnostic & Management Challenges in Resource-Limited Settings

Scrub typhus is a zoonotic febrile illness caused by Orientia tsutsugamushi and transmitted by Leptotrombidium larvae. Scrub typhus often presents with nonspecific clinical features, and ranges in severity from mild illness to multiorgan failure and fatality. The disease is primarily found in the Asia-Pacific rim, including India, Pakistan, Thailand, Malaysia, Korea, and China. Due to frequent limitations in healthcare resources in many of these countries, the diagnosis and management of scrub typhus meningoencephalitis pose unique challenges. This review focuses on the epidemiology, clinical features, diagnostic testing, and management modalities in such resource-limited settings. Exercising a high index of clinical suspicion and timely diagnostic tests and management strategies are vital to prevent life-threatening complications of this treatable illness.

Evaluation of the Therapeutic Effect of Antibiotics on Scrub Typhus: A Systematic Review and Network Meta-Analysis

Background

To explore the efficacy and safety of drugs in patients with scrub typhus.

Methods

For this systematic review and network meta-analysis, we searched PubMed, Embase, Web of Science, Cochrane Central Register of Clinical Trials, China National Knowledge Infrastructure (CNKI), and Wanfang data (WF) up to December 2021. All randomized controlled trials (RCTs) of antibiotics used to treat scrub typhus were included without language or date restrictions. The overall effectiveness was evaluated from 4 perspectives: cure rate (CR), defervescence time (DT), gastrointestinal symptoms–adverse events (GS-AD), and abnormal blood count–adverse events (ABC-AD). The quality of evidence was evaluated using the Cochrane Risk of Bias tool and GRADE system.

Results

Sixteen studies involving 1,582 patients were included to evaluate 7 drugs, namely, azithromycin, doxycycline, chloramphenicol, tetracycline, rifampin, moxifloxacin, and telithromycin. In this network meta-analysis, rifampicin (82%) and chloramphenicol (65%) were more effective in terms of CR, and moxifloxacin (3%) from the quinolone family was the worst. Azithromycin caused the fewest events in terms of ABC-AD. No differences were found in this network meta-analysis (NMA) in terms of DT and GS-AD.

Conclusions

Rifampicin was associated with the highest CR benefit and the lowest risk of DT when used to treat patients with scrub typhus, except in areas where tuberculosis (TB) was endemic. Azithromycin was found to be better in CR and was associated with a lower probability of GS-AD and ABC-AD; therefore, it may be considered to treat pregnant women and children. Moxifloxacin had a much lower CR than other drugs and is, therefore, not recommended for the management of scrub typhus.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42021287837.

Clinical profile and predictors of therapeutic outcome with azithromycin in pediatric scrub typhus: A study from Eastern India

In this prospective study, children from 1-month to 12-years, admitted with positive IgM ELISA testing for scrub typhus, were enrolled over 1-year and administered an empirical single dose of azithromycin (10 mg/kg). All 189 (median age 4.84-years) children had fever with median duration of 8 days at admission. Shortness of breath, altered sensorium, headache, lymphadenopathy, hepatosplenomegaly, pallor, oedema and hypotension were the most prominent symptoms/signs. About 46% of children developed complications, among them hepatic, neurological and cardiovascular were most common. Our study showed a remarkable response to azithromycin, with mean defervescence of 32 h and no mortality. The presence of shortness of breath, headache, altered sensorium, hepatosplenomegaly, meningeal signs, severe anemia, leucocytosis, hyponatremia along with/without any of above mentioned three systemic complications were independent predictors for delayed treatment response by multivariate logistic regression analysis. Hepatic, neurological and cardiovascular complications are an emerging trend. Empiric azithromycin based on clinical suspicion of scrub typhus can be lifesaving.

Acalculous Cholecystitis in a Young Adult with Scrub Typhus: A Case Report and Epidemiology of Scrub Typhus in the Maldives

Scrub typhus is a neglected tropical disease predominantly occurring in Asia. The causative agent is a bacterium transmitted by the larval stage of mites found in rural vegetation in endemic regions. Cases of scrub typhus frequently present as acute undifferentiated febrile illness, and without early diagnosis and treatment, the disease can develop fatal complications. We retrospectively reviewed de-identified data from a 23-year-old woman who presented to an emergency department with complaints of worsening abdominal pain. On presentation, she appeared jaundiced and toxic-looking. Other positive findings on abdominal examination were a positive Murphey’s sign, abdominal guarding and hepatosplenomegaly. Magnetic resonance cholangiopancreatography demonstrated acalculous cholecystitis. Additional findings included eschar on the medial aspect of the left thigh with inguinal regional lymphadenopathy. Further, positive results were obtained for immunoglobulins M and G, confirming scrub typhus. The workup for other infectious causes of acute acalculous cholecystitis (AAC) detected antibodies against human herpesvirus 4 (Epstein–Barr virus), suggesting an alternative cause of AAC. Whether that represented re-activation of the Epstein–Barr virus could not be determined. As other reports have described acute acalculous cholecystitis in adult scrub typhus patients, we recommend doxycycline to treat acute acalculous cholecystitis in endemic regions while awaiting serological confirmation.

The Early Diagnosis of Scrub Typhus by Metagenomic Next-Generation Sequencing

Introduction: Scrub typhus is a mite-borne infection widespread in Southeast Asia, with clinical symptoms such as fever, chills, skin rash, eschar at the bite site, and other signs of acute febrile illness. The Rickettsia pathogen (Orientia tsutsugamushi) is always difficult to be diagnosed at an early stage by traditional clinical diagnostic methods, especially for patients without typical eschar. This greatly increases the mortality of patients with scrub typhus. A new approach should be introduced to improve its clinical diagnosis.

Methods: During May 2018 to March 2021, 13 samples from 10 patients with suspected scrub typhus were collected. Metagenomic next-generation sequencing (mNGS) and other diagnostic methods (including serology using Weil–Felix reaction and indirect immunofluorescence test (IIFT) for scrub typhus and respiratory tract profile IgM as well as culture for routine bacteria) were used to identify the pathogens in this study.

Results: The results of mNGS were all positive, with mapped reads of O. tsutsugamushi ranging from 1 to 460. Eight patients (80%) were diagnosed as scrub typhus. The other two were diagnosed as suspected scrub typhus due to the limited number of reads of the pathogen (one and two, respectively). According to clinical evidences, nine of the 10 patients were finally diagnosed as scrub typhus, except for patient 9 (suspected scrub typhus by mNGS with one specific reads of the pathogen) diagnosed as acute exacerbation of chronic obstructive pulmonary disease. For the five scrub typhus patients without typical eschar, mNGS gave all positive results (4–460 specific reads). For other methods, only Weil–Felix reaction of one patient detected the pathogen. In addition, the respiratory tract profile (IgM) detected various pathogens, but all were confirmed to be false positive.

Conclusions: mNGS performed better than conventional clinical methods to early diagnose scrub typhus. This approach can be routinely carried out for early and precise diagnosis in clinical infections, especially for those hard to be identified by traditional diagnostic methods.

Scrub Typhus: Report of Three Cases From Rural Nepal and a Brief Literature Review

Scrub typhus is endemic among farmers in the rural southern part of Nepal. It is grossly underdiagnosed due to a lack of clinical suspicion and inadequate testing facilities. The most common clinical features of the disease include fever, rashes, vomiting, myalgia, and eschar. The disease may present with ocular changes such as conjunctival injection, gastrointestinal features such as hepatitis and splenomegaly, acute kidney injury (AKI), or neurological findings in the form of meningoencephalitis. Herein, we present a report of three cases of scrub typhus from a rural part of South-west Nepal who failed to receive appropriate treatment initially. One of the patients recovered well with the treatment, the other developed AKI but recovered over the next few weeks. One of the patients died due to sepsis/multiorgan failure secondary to scrub typhus. While managing such cases in places with limited diagnostic facilities, the incorporation of early appropriate empirical therapy for scrub typhus after a careful clinical assessment prevents complications and saves lives.

Systematic review of the scrub typhus treatment landscape: Assessing the feasibility of an individual participant-level data (IPD) platform

Background

Scrub typhus is an acute febrile illness caused by intracellular bacteria from the genus Orientia. It is estimated that one billion people are at risk, with one million cases annually mainly affecting rural areas in Asia-Oceania. Relative to its burden, scrub typhus is understudied, and treatment recommendations vary with poor evidence base. These knowledge gaps could be addressed by establishing an individual participant-level data (IPD) platform, which would enable pooled, more detailed and statistically powered analyses to be conducted. This study aims to assess the characteristics of scrub typhus treatment studies and explore the feasibility and potential value of developing a scrub typhus IPD platform to address unanswered research questions.

Methodology/principal findings

We conducted a systematic literature review looking for prospective scrub typhus clinical treatment studies published from 1998 to 2020. Six electronic databases (Ovid Embase, Ovid Medline, Ovid Global Health, Cochrane Library, Scopus, Global Index Medicus), ClinicalTrials.gov, and WHO ICTRP were searched. We extracted data on study design, treatment tested, patient characteristics, diagnostic methods, geographical location, outcome measures, and statistical methodology.

Among 3,100 articles screened, 127 were included in the analysis. 12,079 participants from 12 countries were enrolled in the identified studies. ELISA, PCR, and eschar presence were the most commonly used diagnostic methods. Doxycycline, azithromycin, and chloramphenicol were the most commonly administered antibiotics. Mortality, complications, adverse events, and clinical response were assessed in most studies. There was substantial heterogeneity in the diagnostic methods used, treatment administered (including dosing and duration), and outcome assessed across studies. There were few interventional studies and limited data collected on specific groups such as children and pregnant women.

Conclusions/significance

There were a limited number of interventional trials, highlighting that scrub typhus remains a neglected disease. The heterogeneous nature of the available data reflects the absence of consensus in treatment and research methodologies and poses a significant barrier to aggregating information across available published data without access to the underlying IPD. There is likely to be a substantial amount of data available to address knowledge gaps. Therefore, there is value for an IPD platform that will facilitate pooling and harmonisation of currently scattered data and enable in-depth investigation of priority research questions that can, ultimately, inform clinical practice and improve health outcomes for scrub typhus patients.

Scrub typhus is a febrile illness most commonly found in rural tropical areas. It is caused by a Gram-negative bacteria belonging to the family Rickettsiaceae and transmitted by mites when they feed on vertebrates. There is an estimate of one million cases annually, with an estimated one billion people at risk, mostly in Asia-Oceania. But relative to the scale of the problem, scrub typhus is largely understudied. Evidence-based treatment recommendations by policymakers vary or are non-existent. We searched databases and registries for prospective scrub typhus clinical treatment studies published from 1998 to 2020 and reviewed them. Data from clinical trials and particularly for specific groups, such as pregnant women and children, were minimal. The methods used to measure treatment efficacy were heterogeneous, making it difficult to directly compare or conduct a meta-analysis based on aggregated data. One way to improve the current level of evidence would be by pooling and analysing individual participant-level data (IPD), i.e. the raw data from individual participants in completed studies. This review demonstrated that there is scope for developing a database for individual participant data to enable more detailed analyses. IPD meta-analyses could be a way to address knowledge gaps such as optimum dosing for children and pregnant women.

Establishment of a Rhesus Macaque Model for Scrub Typhus Transmission: Pilot Study to Evaluate the Minimal Orientia tsutsugamushi Transmission Time by Leptotrombidium chiangraiensis Chiggers

Recently, an intradermal inoculation of the rhesus macaque model of scrub typhus has been characterized at our institution. The current project was to establish a rhesus macaque model of scrub typhus using the naturally infected chigger challenge method that faithfully mimics the natural route of pathogen transmission to fully understand the host-pathogen-vector interactions influencing pathogen transmission. Unlike the needle-based inoculation route, Orientia tsutsugamushi-infected chiggers introduce both pathogen and chigger saliva into the host epidermis at the bite site. However, information on the interaction or influence of chigger saliva on pathogenesis and immunity of host has been limited, consequently hindering vaccine development and transmission-blocking studies. To characterize chigger inoculated O. tsutsugamushi in rhesus macaques, we determined the minimum chigger attachment time required to efficiently transmit O. tsutsugamushi to the immunocompetent hosts and preliminary assessed clinical parameters, course of bacterial infection, and host’s immunological response to identifying potential factors influencing pathogen infection. Chigger infestation on hosts resulted in: (i) Rapid transmission of O. tsutsugamushi within 1 h and (ii) antigen-specific type I and II T-cell responses were markedly increased during the acute phase of infection, suggesting that both systems play critical roles in response to the pathogen control during the primary infection. In summary, we demonstrate that O. tsutsugamushi infection in rhesus macaques via chigger challenge recapitulates the time of disease onset and bacteremia observed in scrub typhus patients. Levels of proinflammatory cytokines and chemokines were positively correlated with bacteremia.

Pan-proteome profiling of emerging and re-emerging zoonotic pathogen Orientia tsutsugamushi for getting insight into microbial pathogenesis

With the occurrence and evolution of antibiotic and multidrug resistance in bacteria most of the existing remedies are becoming ineffective. The pan-proteome exploration of the bacterial pathogens helps to identify the wide spectrum therapeutic targets which will be effective against all strains in a species. The current study is focused on the pan-proteome profiling of zoonotic pathogen Orientia tsutsugamushi (Ott) for the identification of potential therapeutic targets. The pan-proteome of Ott is estimated to be extensive in nature that has 1429 protein clusters, out of which 694 were core, 391 were accessory, and 344 were unique. It was revealed that 622 proteins were essential, 222 proteins were virulent factors, and 42 proteins were involved in antibiotic resistance. The potential therapeutic targets were further classified into eleven broad classes among which gene expression and regulation, transport, and metabolism were dominant. The biological interactome analysis of therapeutic targets revealed that an ample amount of interactions were present among the proteins involved in DNA replication, ribosome assembly, cellwall metabolism, cell division, and antimicrobial resistance. The predicted therapeutic targets from the pan-proteome of Ott are involved in various biological processes, virulence, and antibiotic resistance; hence envisioned as potential candidates for drug discovery to combat scrub typhus.

Genome-Wide Association Study Identifies Eight Novel Loci for Susceptibility of Scrub Typhus and Highlights Immune-Related Signaling Pathways in Its Pathogenesis

Scrub typhus is a fatal zoonotic disease caused by Orientia tsutsugamushi. This disease is accompanied by systemic vasculitis, lymphadenopathy, headache, myalgia, and eschar. In recent studies, a novel strain that is resistant to current medical treatment was identified in Thailand. Thus, the development of new specific drugs for scrub typhus is needed. However, the exact molecular mechanism governing the progression of scrub typhus has not been fully elucidated. To understand disease-related genetic factors and mechanisms associated with the progression of scrub typhus, we performed a genome-wide association study (GWAS) in scrub typhus-infected patients and found a scrub typhus-related signaling pathway by molecular interaction search tool (MIST) and PANTHER. We identified eight potent scrub typhus-related single nucleotide polymorphisms (SNPs) located on the PRMT6, PLGLB2, DTWD2, BATF, JDP2, ONECUT1, WDR72, KLK, MAP3K7, and TGFBR2 genes using a GWAS. We also identified 224 genes by analyzing protein-protein interactions among candidate genes of scrub typhus and identified 15 signaling pathways associated with over 10 genes by classifying these genes according to signaling pathways. The signaling pathway with the largest number of associated genes was the gonadotropin-releasing hormone receptor pathway, followed by the TGF-beta signaling pathway and the apoptosis signaling pathway. To the best of our knowledge, this report describes the first GWAS in scrub typhus.

Scrub Typhus and the Misconception of Doxycycline Resistance

Scrub typhus, a neglected infectious disease caused by the obligate intracellular bacterium Orientia tsutsugamushi, is a major cause of fever across the Asia Pacific region with more than a billion people at risk. Treatment with antibiotics such as doxycycline or chloramphenicol is effective for the majority of patients. In the 1990s, reports from northern Thailand raised a troubling observation; some scrub typhus patients responded poorly to doxycycline, which investigators attributed to doxycycline resistance. Despite the controversial nature of these reports, independent verification was neglected, with subsequent studies speculating on the role of doxycycline resistance in contributing to failure of treatment or prophylaxis. In this review, we have outlined the evidence for drug-resistant Orientia tsutsugamushi, assessed the evidence for doxycycline resistance, and highlight more recent findings unsupportive of doxycycline resistance. We conclude that doxycycline resistance is a misconception, with treatment outcome likely to be determined by other bacterial, host, and pharmacological factors.

Vector-borne diseases in pregnancy

Vector-borne infections cause a significant proportion of world-wide morbidity and mortality and many are increasing in incidence. This is due to a combination of factors, primarily environmental change, encroachment of human habitats from urban to peri-urban areas and rural to previously uninhabited areas, persistence of poverty, malnutrition and resource limitation in geographical areas where these diseases are endemic. Pregnant women represent the single largest ‘at risk’ group, due to immune-modulation and a unique physiological state. Many of these diseases have not benefitted from the same level of drug development as other infectious and medical domains, a factor attributing to the ‘neglected tropical disease’ title many vector-borne diseases hold. Pregnancy compounds this issue as data for safety and efficacy for many drugs is practically non-existent, precluding exposure in pregnancy to many first-line therapeutic agents for ‘fear of the unknown’ or overstated adverse pregnancy-foetal outcomes. In this review, major vector-borne diseases, their impact on pregnancy outcomes, current treatment, vaccination and short-comings of current medical practice for pregnant women will be discussed.

Efficacy and Safety of Antibiotics for Treatment of Scrub Typhus: A Network Meta-analysis

Importance

Antibiotics have been used for many years to treat scrub typhus, but their efficacy and safety have not been studied thoroughly.

Objective

To compare and rank different antibiotics to identify which one can safely eliminate Orientia tsutsugamushi and efficiently alleviate fever in patients with scrub typhus.

Data Sources

An electronic search of PubMed and Embase was conducted, from database inception to July 12, 2019. The study was conducted from July 12 to September 2, 2019.

Study Selection

Randomized clinical trials and retrospective studies that evaluated the use of antibiotics for treatment in patients diagnosed with scrub typhus caused by O tsutsugamushi were included. Records of articles in English were considered eligible. Studies were assessed independently by 2 reviewers, with disagreement resolved by consensus. Of 6408 studies initially identified, 10 randomized clinical trials and 4 retrospective study met the criteria for further analysis.

Data Extraction and Synthesis

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension statement for systematic reviews incorporating network meta-analyses of health care interventions. Data were independently extracted by 2 reviewers and synthesized with frequentist random-effects network meta-analyses.

Main Outcomes and Measures

The primary outcome was efficacy of the antibiotic, considered as the number of patients who achieved complete healing with an antibiotic. Safety, defined as the prevalence of adverse events associated with the antibiotics, was the secondary outcome, and defervescence time was the tertiary outcome. P scores (scale of 0 to 1, with 1 indicating superiority to other treatments) were used to rank the efficacy, safety, and defeverescence time of the antibiotics.

Results

Three searches for articles in Embase and PubMed identified 10 randomized clinical trials (888 participants) and 4 retrospective studies (323 participants) for further analyses. No particular treatment regimen showed a significant advantage or disadvantage with regard to efficacy or safety. However, meta-analysis of retrospective studies indicated that clarithromycin (P score = 0.8730) alleviated fever more efficiently than other antibiotics.

Conclusions and Relevance

No treatment regimen reported in this network meta-analysis showed a significant advantage or disadvantage with regard to efficacy or safety. However, clarithromycin might be a better choice than the other drugs for alleviating fever.

Scrub typhus with multi-organ dysfunction syndrome and immune thrombocytopenia: a case report and review of the literature

BACKGROUND

Scrub typhus is an acute infectious zoonotic disease caused by Orientia tsutsugamushi. Multi-organ dysfunction secondary to scrub typhus is hard to diagnose and has a high mortality rate. Only one case of scrub typhus with multi-organ dysfunction syndrome and immune thrombocytopenia has been reported thus far. In this study, we report a second case of scrub typhus with multi-organ dysfunction syndrome and immune thrombocytopenia, and we summarize its diagnosis and treatment.

CASE PRESENTATION

A 43-year-old Han Chinese woman, a sanitation worker, was admitted to our hospital after 7 days of a skin infection and 5 days of a sore throat with fever and dizziness. A physical examination revealed the presence of an eschar on the right side of her neck. She had a history of insect bites during her sanitation work. A diagnostic evaluation identified scrub typhus as the primary illness, which was associated with multi-organ dysfunction syndrome and immune thrombocytopenia. She recovered completely after 15 days of treatment and extensive symptomatic supportive care.

CONCLUSION

We report a second case of tsutsugamushi disease with multi-organ dysfunction syndrome and immune thrombocytopenia, which resolved after treatment and extensive care.

An Unusual Clinical Presentation of Scrub Typhus

Scrub typhus is still underdiagnosed despite a resurgence in incidence as the clinical presentation is often atypical leading to low index of suspicion among clinicians. We report a case of a young girl presenting as lobar pneumonia and diagnosed as scrub typhus. Despite such a classical picture of community-acquired pneumonia on clinical presentation and radiological findings the patient was found to have scrub typhus serologically thereby posing a diagnostic dilemma. Upon serological confirmation, doxycycline therapy was initiated followed by a rapid and complete resolution of pneumonia, both clinically and radiographically. This case report highlights the importance of recognizing an uncommon clinical presentation of this common tropical disease and its prompt diagnosis and treatment. 

Clinical profile, complications and outcome of scrub typhus in children: A hospital based observational study in central Nepal

Background

Scrub typhus, an important cause of unexplained fever, is grossly neglected and often misdiagnosed in low and middle income countries like Nepal. The main aim of this study was to report on the clinical profile and complications of scrub typhus and its outcome in Nepalese children.

Methods

A prospective observational study was carried out in children aged 1–16 years, admitted to a tertiary care hospital of central Nepal in between July 2016- Aug 2017. Scrub typhus was diagnosed with IgM ELISA.

Results

All cases of scrub typhus (n = 76) presented with fever and commonly had other symptoms such as headache (75%), myalgia (68.4%), vomiting (64.5%), nausea (59.2%), abdominal pain (57.9%), cough (35.5%), shortness of breath (22.4%), altered sensorium (14.5%), rashes (13.2%) and seizures (11.8%). Important clinical signs noticed were lymphadenopathy (60.5%), hepatomegaly (47.4%), edema (26.3%), jaundice (26.3%), and splenomegaly (15.8%). About 12% (n = 9) had necrotic eschar. Similarly, thrombocytopenia, raised liver enzymes and raised creatinine values were seen in 36.9%, 34.2% and 65.8% respectively. The most common complications were myocarditis (72.4%), hypoalbuminemia (71.1%), severe thrombocytopenia (22.4%), renal impairment (65.8%), hyponatremia (48.7%) and hepatitis (34.2%). Over two-thirds (69.70%) of the cases were treated with doxycycline followed by combination with azithromycin in the remaining 18.4%. Overall, mortality rate in this group was 3.9%.

Conclusions

Scrub typhus should be considered as a differential in any community acquired acute undifferentiated febrile illness regardless of the presence of an eschar. Myocarditis and acute kidney injury are important complications which when addressed early can prevent mortality. Use of doxycycline showed a favorable outcome.

Clinical and Epidemiological Patterns of Scrub Typhus, an Emerging Disease in Bhutan

Scrub typhus (ST) is a vector-borne rickettsial infection causing acute febrile illness. The re-emergence of ST in the Asia-Pacific region represents a serious public health threat. ST was first detected in Bhutan in 2008. However, the disease is likely to be under-diagnosed and under-reported, and the true impact is difficult to estimate. At the end of 2014, the SD Bioline Tsutsugamushi Test^TM rapid diagnostic test (RDT) kits became available in all hospitals to assist clinicians in diagnosing ST. We conducted a retrospective descriptive study, reviewing records from all hospitals of Bhutan to identify all RDT-positive clinical cases of ST in Bhutan in 2015. The aim was to evaluate the burden of ST in Bhutan, describe the demographic, spatial and temporal patterns of disease, and identify the typical clinical presentations. The annual incidence of RDT-positive cases of ST reporting to Bhutanese hospitals in 2015 was estimated to be 62 per 100,000 population at risk. The incidence of disease was highest in the southern districts with a subtropical climate and a high level of agricultural production. The highest proportion of cases (87%) was rural residents, with farmers being the main occupational category. The disease was strongly seasonal, with 97% of cases occurring between June and November, coinciding with the monsoon and agricultural production seasons. Common ST symptoms were not specific, and an eschar was noted by clinicians in only 7.4% of cases, which is likely to contribute to an under-diagnosis of ST. ST represents an important and neglected burden, especially in rural communities in Bhutan. The outcomes of this study will inform public health measures such as timely-awareness programmes for clinicians and the public in high-risk areas, to improve the diagnosis, treatment and clinical outcomes of this disease.