Renal Manifestation in Scrub Typhus during a Major Outbreak in Central Nepal

Renal involvement and acute kidney injury (AKI) are common clinical manifestations seen in scrub typhus, a vector-borne tropical disease. There are no data on renal manifestation in scrub typhus in Nepal. We conducted a prospective study to analyze the incidence, urinary abnormalities, course, severity, outcome, and the predictors of AKI in patients with scrub typhus during a major outbreak in Central Nepal. Total 1398 patients admitted with acute febrile illness were subjected for Scrub Typhus Detect™ Immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) test, of which 502 (35.90%) patients tested positive and were included in the study. Mean age of the patients was 30.37 ± 18.81 years (range, 1-79 years) with 26.29% in the pediatric age group. Female-to-male ratio was 1.26:1. Mean duration of fever was 6.8 ± 3.1 days. Mean IgM ELISA value for scrub typhus was 2.17 ± 1.70 without difference in AKI and non-AKI groups (2.17 ± 1.76 vs. 2.16 ± 1.62; P = 0.94). Urinary abnormalities were seen in 42.3% of patients. Mean serum creatinine was 1.37 ± 0.69 mg/dl with significant difference in two groups (1.85 ± 0.87 vs. 1.03 ± 0.17; P = 0.003). AKI was seen in 35.8% of patients with majority having Stage 1 AKI (68.3%) followed by Stage 2 (34.1%) and Stage 3 (1.2%). Hemodialysis was required for 3.94% of patients. In 54% of patients, AKI occurred in fifth and sixth day of fever. ICU admission was required for 18.73% of patients and 8.57% required ventilator support. Mortality rate was 1.79%, which was higher among patients with AKI (2.96% vs. 1.0%; P = 0.106). Multivariate analysis revealed that the presence of pneumonia, shock, and acute respiratory distress syndrome predicted the development of AKI.

Infection of Rodents by Orientia tsutsugamushi, the Agent of Scrub Typhus in Relation to Land Use in Thailand

The relationship between land use structures and occurrence of the scrub typhus agent, Orientia tsutsugamushi, in small wild mammals was investigated in three provinces of Thailand: Buriram, Loei, and Nan. O. tsutsugamushi detection was performed using 16S ribosomal DNA (rDNA) amplicon sequencing approach using Miseq Illumina platform. In total, 387 animals (rodents and shrews) were examined for the infection. The 16S rDNA sequences of the bacterium were found in nine animals, namely Bandicota savilei, Berylmys bowersi, Leopoldamys edwardsi, Rattus exulans, R. tanezumi, and Rattus sp. phylogenetic clade 3, yielding 2.3% infection rate, with two new rodent species found infected by the bacterium in Thailand: B. bowersi and L. edwardsi. Using a generalized linear mixed model (GLMM) and Random Forest analyses for investigating the association between human-land use and occurrence of the bacterium, forest habitat appeared as a strong explicative variable of rodent infection, meaning that O. tsutsugamushi-infected animals were more likely found in forest-covered habitats. In terms of public health implementation, our results suggest that heterogenous forested areas including forest-converted agricultural land, reforestation areas, or fallows, are potential habitats for O. tsutsugamushi transmission. Further understanding of population dynamics of the vectors and their hosts in these habitats could be beneficial for the prevention of this neglected zoonotic disease.

Prevalence and Phylogenetic Analysis of Orientia tsutsugamushi in Rodents and Mites from Central India

Orientia tsutsugamushi, the causative agent of scrub typhus in humans, is an obligate intracytosolic bacterium transmitted among animals and to humans by some species of larval trombiculid mites (chiggers) and is hosted mainly by rodents. In this study, we attempted detection of O. tsutsugamushi from blood and tissue samples of rodents trapped from different locations in Central India using PCR targeting the 56 kDa outer membrane protein gene and the 47 kDa high temperature transmembrane protein gene. A total of 59 rodent samples comprising 38 of blood collected from domestic and public surroundings and 21 of tissue from agricultural farm were included in this study. The 56 kDa outer membrane protein gene was detected from 10 of 59 samples by PCR, and the 47 kDa protein gene was detected from 4 of 59 samples by nested-PCR. Mites collected from the rodents were identified as Ornithonyssus bacoti, and one of five pooled samples was found to be positive for O. tsutsugamushi using PCR targeting 56 kDa outer membrane protein gene. Thus, perpetuation of O. tsutsugamushi among rodents and mites was detected constituting a potential public health concern.

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

Background:

In the recent past, scrub typhus (ST) has been reported from different parts of India, based on Weil-Felix/enzyme-linked immunosorbent assay (ELISA)/indirect immunofluorescence assay (IFA). Molecular tests are applied only by a few researchers.

Aims:

Evaluation of a new commercial real time polymerase chain reaction (PCR) kit for molecular diagnosis of ST by comparing it with the commonly used IgM ELISA is our aim.

Settings and Design:

ST has been reported all over India including Puducherry and surrounding Tamil Nadu and identified as endemic for ST. This study was designed to correlate antibody detection by IgM ELISA and Orientia tsutsugamushi DNA in real time PCR.

Materials and Methods:

ST IgM ELISA (InBios Inc., USA) was carried out for 170 consecutive patients who presented with the symptoms of acute ST during 11 months (November, 2015– September, 2016). All 77 of these patients with IgM ELISA positivity and 49 of 93 IgM ELISA negative patients were subjected to real time PCR (Geno-Sen's ST real time PCR, Himachal Pradesh, India).

Statistical Analysis:

Statistical analysis for clinical and laboratory results was performed using IBM SPSS Statistics 17 for Windows (SPSS Inc., Chicago, USA). Chi-square test with Yates correction (Fisher's test) was employed for a small number of samples.

Results and Conclusion:

Among 77 suspected cases of acute ST with IgM ELISA positivity and 49 IgM negative patients, 42 and 7 were positive, respectively, for O. tsutsugamushi 56-kDa type-specific gene in real time PCR kit. Until ST IFA, the gold standard diagnostic test, is properly validated in India, diagnosis of acute ST will depend on both ELISA and quantitative PCR.

A Case of Scrub Typhus Related Encephalopathy Presenting as Rapidly Progressive Dementia

Background

An infection known to be a major cause of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS). Rapidly progressive dementia is a neurological condition in which dementia progresses in a short period of time.

Case Report

We report on a 78-year-old woman presenting with a rapid decline in cognitive function resulting from a scrub typhus infection. Diffusion weighted images showed a signal intensity at the splenium, and subcortical white matter of both hemispheres suggesting MERS. On the neuropsychological test, the patient showed frontal executive dysfunction.

Conclusions

This case suggests that diagnosticians should consider the possibility that a MERS patient with a rapidly cognitive decline could have a scrub typhus infection because early diagnosis of scrub typhus is very important in this aspect of the treatment.

Comparative effectiveness of azithromycin for treating scrub typhus: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Scrub typhus is a zoonotic disease that remains an important health threat in endemic areas. Appropriate anti-rickettsial treatment ensures a successful recovery. Doxycycline is a recommended drug, but it is contraindicated in pregnant women and young children. Azithromycin is a safer alternative drug, but its effectiveness remains largely unclear. Herein, we conducted a systematic review and meta-analysis to determine the effectiveness of azithromycin.

METHODS

Studies that investigated azithromycin in treating scrub typhus were systematically identified from electronic databases up to December 2016. Information regarding study population, disease severity, treatment protocols, and responses was extracted and analyzed.

RESULTS

In this review, 5 studies were included, which comprised a total of 427 patients. When comparing the treatment failure rate, we observed a favorable outcome in patients treated with azithromycin (risk ratio [RR] 0.83, 95% confidence interval [CI] 0.23-2.98). However, patients in the azithromycin group had longer time to defervescence (mean difference 4.38 hours, 95% CI -2.51 to 11.27) and higher rate of fever for more than 48 hours (RR 1.31, 95% CI 0.81-2.12). Moreover, patients treated with azithromycin had less adverse effects (RR 0.8, 95% CI 0.42-1.52).

CONCLUSIONS

Azithromycin is as effective as other anti-rickettsial drugs with higher treatment success rates, lower frequency of adverse effects, and longer time to defervescence (GRADE 2B). Therefore, it is reasonable to use azithromycin as the first-line treatment against scrub typhus. Further studies are warranted to elucidate the effectiveness of azithromycin in specific patient groups, at high dose and influence of drug resistance.

Typhoid and Scrub Typhus Coinfection in a Returned Traveler

This is a case report of a 12-year-old returned traveler with typhoid and scrub typhus coinfection. The diagnosis of typhoid was made early with blood cultures and Widal Weil Felix serology. Persistent fever despite appropriate antibiotics for typhoid fever prompted a search for concomitant infection, which led to the diagnosis of scrub typhus confirmed by Orientia tsutsugamushi serology. The patient was given doxycycline with good clinical response. Scrub typhus infection should be an early consideration in the differential diagnoses of fever in a returned traveler from regions where it is endemic. Coinfections should be taken into consideration particularly when fever or symptoms persist despite adequate therapy for a previously identified microorganism.

Prevalence and risk factors for scrub typhus in South India

OBJECTIVE

To determine the prevalence and risk factors of scrub typhus in Tamil Nadu, South India.

METHODS

We performed a clustered seroprevalence study of the areas around Vellore. All participants completed a risk factor survey, with seropositive and seronegative participants acting as cases and controls, respectively, in a risk factor analysis. After univariate analysis, variables found to be significant underwent multivariate analysis.

RESULTS

Of 721 people participating in this study, 31.8% tested seropositive. By univariate analysis, after accounting for clustering, having a house that was clustered with other houses, having a fewer rooms in a house, having fewer people living in a household, defecating outside, female sex, age >60 years, shorter height, lower weight, smaller body mass index and smaller mid-upper arm circumference were found to be significantly associated with seropositivity. After multivariate regression modelling, living in a house clustered with other houses, female sex and age >60 years were significantly associated with scrub typhus exposure.

CONCLUSIONS

Overall, scrub typhus is much more common than previously thought. Previously described individual environmental and habitual risk factors seem to have less importance in South India, perhaps because of the overall scrub typhus-conducive nature of the environment in this region.

Use of Multiplex Real-Time PCR To Diagnose Scrub Typhus

Scrub typhus, caused by Orientia tsutsugamushi, is a common cause of acute undifferentiated febrile illness in the Asia-Pacific region. However, its nonspecific clinical manifestation often prevents early diagnosis. We propose the use of PCR and serologic tests as diagnostic tools. Here, we developed a multiplex real-time PCR assay using hydrolysis (TaqMan) probes targeting O. tsutsugamushi 47-kDa, groEL, and human interferon beta (IFN-β gene) genes to improve early diagnosis of scrub typhus. The amplification efficiency was higher than 94%, and the lower detection limit was 10 copies per reaction. We used a human gene as an internal DNA quality and quantity control. To determine the sensitivity of this PCR assay, we selected patients with confirmed scrub typhus who exhibited a clear 4-fold increase in the level of IgG and/or IgM. The PCR assay result was positive in 45 of 52 patients, indicating a sensitivity of 86.5% (95% confidence interval [CI]: 74.2 to 94.4). The PCR assessment was negative for all 136 non-scrub typhus patients, indicating a specificity of 100% (95% CI: 97.3 to 100). In addition, this test helped diagnose patients with inconclusive immunofluorescence assay (IFA) results and using single blood samples. In conclusion, the real-time PCR assay proposed here is sensitive and specific in diagnosing scrub typhus. Combining PCR and serologic tests will improve the diagnosis of scrub typhus among patients presenting with acute febrile illness.

[Septic shock with multiple organ failure after returning from Southeast Asia]

For a patient recently returned from a tropical country in intensive care, the leading hypothesis for a fever leading to multiple organ failure is evidently malaria. Nonetheless, many other causes are possible and should be considered: parasites, viruses, and bacteria. A multidisciplinary discussion between specialists in emergency medicine, radiology, pathology, and infectious diseases is essential to start appropriate treatment as quickly as possible without impairing the patient's prognosis.

Differences in Clinical and Laboratory Features for Different Genotypes of Orientia tsutsugamushi in Guangzhou, Southern China

PURPOSE

To describe the genotypes distribution of Orientia tsutsugamushi, in Guangzhou, and explore differences in clinical and laboratory features among genotypes.

METHOD

We collected blood or eschar samples of all scrub typhus cases reported in 2013 from 10 district hospitals positive for PCR. We further tested the PCR-positive samples for DNA sequencing and phylogenetic analysis. We collected the demographic, clinical, and laboratory data by questionnaire and medical records.

RESULT

A total of 589 samples were tested and 40 were PCR positive. Four genotypes were identified: Karp (52.2%), Kato (22.5%), Gilliam (12.5%), and TA763 (7.5%). Two new strains (ZCX90 and CHX5 strain) were previously unidentified in Guangzhou. Gilliam type cases were more likely to have continuous fever (60.0%). Only Kato genotype cases presented with splenomegaly. For laboratory features, Kato group had higher level of white blood cell count (16.44 × 10¹²/L) than normal range and other groups. Total bilirubin and direct bilirubin in Gilliam group (10.10 μM and 3.05 μM, respectively) were both lower than other groups and normal value.

CONCLUSION

Continuous fever and splenomegaly may be the distinctive symptom of Gilliam and Kato genotype cases, respectively. Karp genotype remained dominant in Guangzhou, but attention should be paid to the emergence of new types or variation of existing genotypes.

Clinical Score to Differentiate Scrub Typhus and Dengue: A Tool to Differentiate Scrub Typhus and Dengue

Background:

Dengue and scrub typhus share similar clinical and epidemiological features, and are difficult to differentiate at initial presentation. Many places are endemic to both these infections where they comprise the majority of acute undifferentiated febrile illnesses.

Materials and Methods:

We aimed to develop a score that can differentiate scrub typhus from dengue. In this cross-sectional study, 188 cases of scrub typhus and 201 cases of dengue infection who presented to the emergency department or medicine outpatient clinic from September 2012 to April 2013 were included. Univariate followed by multivariate logistic regression analysis was performed to identify clinical features and laboratory results that were significantly different between the two groups. Each variable was assigned scores based on the strength of association and receiver operating characteristics area under the curve (ROC-AUC) was generated and compared. Six scoring models were explored to ascertain the model with the best fit.

Results:

Model 2 was developed using the following six variables: oxygen saturation (>90%, ≤90%), total white blood cell count (<4000, 4001–7000 and >7000 cells/cumm), hemoglobin (≤14 and >14 g/dL), total bilirubin (<2 and ≥2 mg/dL), serum glutamic oxaloacetic transaminase (>200 and ≥200 IU/dL), and altered sensorium (present or absent). Each variable was assigned scores based on its strength of association. The AUC-ROC curve (95% confidence interval) for model 2 was 0.84 (0.79–0.89). At the cut off score of 13, the sensitivity and specificity were 85% and 77% respectively, with a higher score favoring dengue.

Conclusion:

In areas of high burden of ST and dengue, model 2 (the “clinical score to differentiate scrub typhus and dengue fever”) is a simple and rapid clinical scoring system that may be used to differentiate scrub typhus and dengue at initial presentation.

Severe Pediatric Acute Respiratory Distress Syndrome Due to Scrub Typhus: Successful Ventilation with Airway Pressure Release Ventilation Mode after Becoming Refractory to Protective Ventilation

Scrub typhus can affect lungs from mild illness like pneumonitis to a severe illness like acute respiratory distress syndrome (ARDS). Such patients may be very challenging to treat when their hypoxemia becomes severe and refractory to treatment. Main treatment is supportive in terms of mechanical ventilation. In adult ARDS, low tidal volume (TV) ventilation has been recommended, but there is no consensus on most effective ventilation mode in children. We present a case of a 12-year-old girl who developed severe ARDS (PO₂/FiO₂ ratio – 58), refractory to low TV ventilation. There was a rapid improvement in oxygenation on the application of airway pressure release ventilation (APRV) mode within ½ h. She was successfully ventilated and weaned off the ventilator over 5 days. This case highlights the utility of APRV mode of ventilation as a rescue therapy for severe refractory ARDS in children.

Scrub typhus meningitis in a renal transplant recipient

Scrub typhus is a rickettsial infection commonly seen in Asia. The clinical presentation ranges from nonspecific febrile illness to potentially fatal multiorgan involvement such as liver, kidney, or lung. Central nervous system involvement is uncommon. We report a 45-year-old female renal transplant recipient who presented with fever, headache, meningeal signs, graft dysfunction, and eschar. IgM antibodies against Orientia tsutsugamushi were positive by enzyme-linked immunosorbent assay. Despite oral doxycycline therapy for 5 days, she did not improve but responded well to intravenous azithromycin. To the best of our knowledge, scrub typhus as a cause of meningitis in a renal transplant recipient has not been reported so far.

Scrub Typhus in Southern Districts of West Bengal

Scrub typhus has been previously reported from north and eastern Indian states and areas such as Kashmir, Himachal Pradesh, Assam, Sikkim, and Darjeeling district of West Bengal. It has also been known to be endemic in some parts of South India (Eastern and Western Ghats). However, no cases have ever been reported from the southern districts of West Bengal. Here, we report five cases of scrub typhus from South 24 Parganas and Kolkata, two districts in the southern part of West Bengal, India.

Tropical Fevers in Indian Intensive Care Units: A Prospective Multicenter Study

Background and Aims

Infections in tropics often present as undifferentiated fevers with organ failures. We conducted this nationwide study to identify the prevalence, profile, resource utilization, and outcome of tropical fevers in Indian Intensive Care Units (ICUs).

Materials and Methods

This was a multicenter prospective observational study done in 34 ICUs across India (July 2013-September 2014). Critically ill adults and children with nonlocalizing fever >48 h and onset < 14 days with any of the following: thrombocytopenia/rash, respiratory distress, renal failure, encephalopathy, jaundice, or multiorgan failure were enrolled consecutively.

Results

Of 456 cases enrolled, 173 were children <12 years. More than half of the participants (58.7%) presented in postmonsoon months (August-October). Thrombocytopenia/rash was the most common presentation (60%) followed by respiratory distress (46%), encephalopathy (28.5%), renal failure (23.5%), jaundice (20%), and multiorgan failure (19%). An etiology could be established in 365 (80.5%) cases. Dengue (n = 105.23%) was the most common followed by scrub typhus (n = 83.18%), encephalitis/meningitis (n = 44.9.6%), malaria (n = 37.8%), and bacterial sepsis (n = 32.7%). Nearly, half (35% invasive; 12% noninvasive) received mechanical ventilation, a quarter (23.4%) required vasoactive therapy in first 24 h and 9% received renal replacement therapy. Median (interquartile range) ICU and hospital length of stay were 4 (3-7) and 7 (5-11.3) days. At 28 days, 76.2% survived without disability, 4.4% had some disability, and 18.4% died. Mortality was higher (27% vs. 15%) in patients with undiagnosed etiology (P < 0.01). On multivariate analysis, multiorgan dysfunction syndrome at admission (odds ratio [95% confidence interval]-2.8 [1.8-6.6]), day 1 Sequential Organ Failure Assessment score (1.2 [1.0-1.3]), and the need for invasive ventilation (8.3 [3.4-20]) were the only independent predictors of unfavorable outcome.

Conclusions

Dengue, scrub typhus, encephalitis, and malaria are the major tropical fevers in Indian ICUs. The data support a syndromic approach, point of care tests, and empiric antimicrobial therapy recommended by Indian Society of Critical Care Medicine in 2014.

Q Fever, Scrub Typhus, and Rickettsial Diseases in Children, Kenya, 2011-2012

To increase knowledge of undifferentiated fevers in Kenya, we tested paired serum samples from febrile children in western Kenya for antibodies against pathogens increasingly recognized to cause febrile illness in Africa. Of patients assessed, 8.9%, 22.4%, 1.1%, and 3.6% had enhanced seroreactivity to Coxiella burnetii, spotted fever group rickettsiae, typhus group rickettsiae, and scrub typhus group orientiae, respectively.

The Epidemiology and Characteristics of Q fever and Co-infections with Scrub Typhus, Murine Typhus or Leptospirosis in Taiwan: A Nationwide Database Study

Q fever (QF) is a worldwide zoonosis associated with outbreaks. Only a few nationwide studies regarding the surveillance and epidemiology of human QF have been reported. Although QF is endemic in Taiwan, a nationwide database investigation of the epidemiology and characteristics of QF and its associations with scrub typhus (ST), murine typhus (MT) and leptospirosis (LS) has never been reported. We analysed nationwide databases of suspected QF, ST, MT and LS cases from October 2007 to December 2014 obtained from the Centers for Disease Control, Taiwan. A total of 468 (4.2%) QF cases were identified among 11 109 suspected QF cases. QF cases were mainly distributed in the southern and Kaohsiung-Pingtung regions but rarely in the eastern region. Compared to non-QF cases, QF cases had significantly higher percentages of males (88.7 versus 66.2%) and high-risk occupations (farming, animal husbandry or veterinary medicine) (16.2 versus 10.5%). But the percentages of specific animal contact, including cattle (0.6 versus 0.8%) and goats (0.9 versus 1.0%), were low in both. The majority of suspected QF cases (89.4%) were simultaneously suspected with ST, MT or LS, and the combinations of suspected diseases differed between regions. The number of suspected QF cases from the eastern region decreased since 2009, which was not observed in other regions. A total of 1420 (12.8%) cases had confirmed diseases, including QF (453, 4.1%), QF+ST (7, 0.06%), QF+MT (4, 0.04%), QF+LS (4, 0.04%), MT (186, 1.7%), ST (545, 4.9%), ST+LS (11, 0.1%) and LS (210, 1.9%). Compared to cases of unknown disease, QF cases had larger percentages of high-risk occupations (16.2 versus 9.6%) but similar histories of animal contact (29.8 versus 25.1%). QF is an endemic disease in southern Taiwan. It is difficult to differentiate QF from ST, MT or LS only by high-risk occupations and history of animal contact, and co-infection of QF with these diseases should be considered.

Protection of Military Personnel Against Vector-Borne Diseases: A Review of Collaborative Work of the Australian and US Military Over the Last 30 Years

Australian and US military medical services have collaborated since World War II to minimize vector-borne diseases such as malaria, dengue, and scrub typhus. In this review, collaboration over the last 30 years is discussed. The collaborative projects and exchange scientist programs have resulted in mutually beneficial outcomes in the fields of drug development and personal protection measures against vector-borne diseases.

Distribution of Eschar in Pediatric Scrub Typhus

BACKGROUND

Identifying an eschar in scrub typhus is useful for initiation of prompt and appropriate antibiotic therapy.

METHODS

The distribution of eschars in all children <15 years of age admitted with confirmed scrub typhus over a 5 year period is described.

RESULTS

Of 431 children admitted with scrub typhus, eschars were present in 176 (40.8%) children with the following distribution: head, face and neck, 33 (19.1%); axillae, 37 (21%); chest and abdomen, 21 (11.9%); genitalia, inguinal region and buttocks, 58 (33%); back, 8 (4.5%); upper extremities, 13 (7.4%); and lower extremities, 5 (2.8%). The commonest sites of eschars were scrotum (27 of 106; 25.5%) and axillae (15 of 106; 14.2%) in males and axillae (22 of 70; 31.4%) and groin (16 of 70; 22.9%) in females. Eschars were seen within skin folds in 100 of 176 (56.8%) children.

CONCLUSION

Children should be carefully examined for the presence of eschar especially in the skin folds of the genitalia, axillae and groin to make an early diagnosis of scrub typhus.

Acute respiratory failure in scrub typhus patients

Respiratory failure is a serious complication of scrub typhus. In this prospective study, all patients with a diagnosis of scrub typhus were included from a single center Intensive Care Unit (ICU). Demographic, clinical characteristics, laboratory, and imaging parameters of these patients at the time of ICU admission were compared. Of the 55 scrub typhus patients, 27 (49%) had an acute respiratory failure. Seventeen patients had acute respiratory distress syndrome, and ten had cardiogenic pulmonary edema. Respiratory supported patients were older had significant chronic lungs disease and high severity illness scores (Acute Physiology and Chronic Health Evaluation-II and Sequential Organ Failure Assessment score). At ICU admission, these patients presented with more deranged laboratory markers, including high bilirubin, high creatine kinase, high lactate, metabolic acidosis, low serum albumin, and presence of ascites. The average ICU and hospital stay were 4.27 ± 2.74 and 6.53 ± 3.52 days, respectively, in the respiratory supported group. Three patients died in respiratory failure group, while only one patient died in nonrespiratory failure group.

Scrub Typhus and Its Causative Agent, Orientia tsutsugamushi

The obligate intracellular bacterium Orientia tsutsugamushi is responsible for more than one million cases of scrub typhus annually throughout the Asia-Pacific region. Human infection occurs via the bite of the larval form (chigger) of several species of trombiculid mites. While in some patients the result of infection is a mild, febrile illness, others experience severe complications, which may even be fatal. This review discusses the genome and biology of the causative agent, the changing epidemiology of scrub typhus, the challenges of its diagnosis, and current treatment recommendations.

Determination of Cutoff of ELISA and Immunofluorescence Assay for Scrub Typhus

Background:

The most common method employed for diagnosis of scrub typhus is serology. It is widely known that demonstration of ≥4-fold rise in titers of antibody in paired sera is required for diagnosis. However, for guidance of initial treatment, there is a need for rapid diagnosis at the time of admission. Therefore, there is a need for standardized region specific cutoff titers at the time of admission.

Materials and Methods:

A total of 258 patients of all age groups with clinically suspected scrub typhus over a period of 24 months (October 2013-October 2015) were enrolled. Serum samples of these patients were subjected to immunofluorescent antibody (IFA) for immunoglobulin M (IgM) (Fuller Labs, USA) with dilutions of 1:64, 1:128, 1:256, and 1:512. Serum samples of all 258 patients were subjected to IgM ELISA (Inbios Inc., USA). Any patient with response to antibiotics within 48 h accompanied by either presence of an eschar or positivity by polymerase chain reaction was taken as positive. Receiver operating characteristic (ROC) curve was drawn to generate cutoff for these tests.

Results:

A total of 20 patients were diagnosed as cases of scrub typhus. The ROC curve analysis revealed a cutoff optical density value of 0.87 with sensitivity and specificity of 100% and 94.12%, respectively. ROC curve analysis of IFA revealed sensitivity and specificity of 100% and 93.5%, respectively at 1:64 dilution.

Conclusion:

Considering cost constraints, centers in and around New Delhi region can use the cutoffs we determined for the diagnosis of scrub typhus.

Scrub typhus associated with hemophagocytic lymphohistiocytosis: A report of six pediatric patients

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening immune disorder that may be inherited or secondary to infection, malignancy or rheumatological disease. The aim of the present study was to highlight the clinical features of scrub typhus-associated HLH in children. A retrospective study was performed on 6 pediatric patients with scrub typhus-associated HLH. For each patient, medical records were reviewed and analyzed, and demographic, clinical and laboratory data and outcomes were collected. The duration of fever prior to admission ranged between 4 and 12 days. All patients exhibited persistent or intermittent fever, eschar, hepatosplenomegaly and lymphadenopathy at the time of diagnosis. Five patients experienced acute respiratory distress syndrome and disseminated intravascular coagulation (DIC) during hospitalization. Thrombocytopenia was detected in all patients with cytopenia involving two or three cell types, simultaneously. Coagulopathy with prolonged prothrombin time and/or activated partial thromboplastin time were noted in all patients. Markedly elevated serum ferritin levels (>1,500 µg/ml) were identified in all patients. Elevated lactate dehydrogenase (>1,000 U/l) was detected in 4 (66.7%) patients and elevated alanine aminotransferase was exhibited by 5 (83/3%) patients. Lung infiltrates and consolidation were the most common imaging findings. Only 1 patient succumbed, with DIC and multi-organ failure. Of the survivors, 1 patient was lost to follow-up, and the remaining patients are in remission with excellent general health, to date. In conclusion, HLH should be considered in severe pediatric cases of scrub typhus. Upon the early recognition of this syndrome, prompt and supportive treatment in the pediatric intensive care unit are vital.