Scrub typhus diagnosis on acute specimens using serological and molecular assays — a 3-year prospective study

Koralur, Munegowda; Singh, Rahul; Varma, Muralidhar; Shenoy, Shalini; Acharya, Vasudeva; Kamath, Asha; Stenos, John; Athan, E.; Bairy, Indira

doi:10.1016/j.diagmicrobio.2018.01.018

Cited by 12 publications

(8 citation statements)

References 43 publications

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“…Due to the great antigenic diversity of Orientia tsutsugamushi strains [28] these diagnostic assays may not detect scrub typhus-specific antibodies of all strains. In a study from South India, 16 out of 240 nested PCR confirmed scrub typhus cases were negative for serological scrub typhus tests [19]. These 16 samples were taken predominantly in the first seven days of illness during which serological tests may often be negative.…”

Section: Discussionmentioning

confidence: 99%

“…This ELISA uses Karp, Kato, Gilliam and TA716 recombinant proteins of the 56-kD outer membrane protein. Commercially available ELISA IgM assays, such as the ones used in this study, have been shown to have a sensitivity and specificity of over 90% in a study from Thailand [18], and 80% sensitivity and 96% specificity in a study from South India [19]. The sensitivity and specificity of IgG ELISA to detect past infection remains to be determined.…”

Section: Methodsmentioning

confidence: 99%

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Hospitalisations and outpatient visits for undifferentiated fever attributable to scrub typhus in rural South India: Retrospective cohort and nested case-control study

et al. 2019

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Background The burden of scrub typhus in endemic areas is poorly understood. This study aimed at estimating the proportion of hospitalisations and outpatient visits for undifferentiated fever in the community that may be attributable to scrub typhus. Methodology and principal findings The study was a retrospective cohort with a nested case-control study conducted in the South Indian state of Tamil Nadu. We conducted house-to-house screening in 48 villages (42965 people, 11964 households) to identify hospitalised or outpatient cases due to undifferentiated fever during the preceding scrub typhus season. We used scrub typhus IgG to determine past infection. We calculated adjusted odds ratios for the association between IgG positivity and case status. Odds ratios were used to estimate population attributable fractions (PAF) indicating the proportion of hospitalised and outpatient fever cases attributable to scrub typhus. We identified 58 cases of hospitalisation and 236 outpatient treatments. 562 people were enrolled as control group to estimate the background IgG sero-prevalence. IgG prevalence was 20.3% in controls, 26.3% in outpatient cases and 43.1% in hospitalised cases. The PAFs suggested that 29.5% of hospitalisations and 6.1% of outpatient cases may have been due to scrub typhus. In villages with a high IgG prevalence (defined as ≥15% among controls), the corresponding PAFs were 43.4% for hospitalisations and 5.6% for outpatients. The estimated annual incidence of scrub typhus was 0.8/1000 people (0.3/1000 in low, and 1.3/1000 in high prevalence villages). Evidence for recall error suggested that the true incidences may be about twice as high as these figures. Conclusions The study suggests scrub typhus as an important cause for febrile hospitalisations in the community. The results confirm the adequacy of empirical treatment for scrub typhus in hospitalised cases with undifferentiated fever. Since scrub typhus may be rare among stable outpatients, the use of empirical treatment remains doubtful in these.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Hospitalisations and outpatient visits for undifferentiated fever attributable to scrub typhus in rural South India: Retrospective cohort and nested case-control study

et al. 2019

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“…Real‐time PCR on blood or eschar biopsy is helpful in diagnosing early‐stage infection ( Paris 2016 ). In some resource‐limited settings, the only serological test available is the Weil‐Felix test, a non‐specific antibody agglutination test that cannot distinguish O tsutsugamushi from other Rickettsial infections ( Koralur 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Antibiotics for treating scrub typhus

Sayed

et al. 2018

Cochrane Database of Systematic Reviews

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Background Scrub typhus, an important cause of acute fever in Asia, is caused by Orientia tsutsugamushi, an obligate intracellular bacterium. Antibiotics currently used to treat scrub typhus include tetracyclines, chloramphenicol, macrolides, and rifampicin. Objectives To assess and compare the effects of different antibiotic regimens for treatment of scrub typhus. Search methods We searched the following databases up to 8 January 2018: the Cochrane Infectious Diseases Group specialized trials register; CENTRAL, in the Cochrane Library (2018, Issue 1); MEDLINE; Embase; LILACS; and the meta Register of Controlled Trials ( m RCT). We checked references and contacted study authors for additional data. We applied no language or date restrictions. Selection criteria Randomized controlled trials (RCTs) or quasi‐RCTs comparing antibiotic regimens in people with the diagnosis of scrub typhus based on clinical symptoms and compatible laboratory tests (excluding the Weil‐Felix test). Data collection and analysis For this update, two review authors re‐extracted all data and assessed the certainty of evidence. We meta‐analysed data to calculate risk ratios (RRs) for dichotomous outcomes when appropriate, and elsewhere tabulated data to facilitate narrative analysis. Main results We included six RCTs and one quasi‐RCT with 548 participants; they took place in the Asia‐Pacific region: Korea (three trials), Malaysia (one trial), and Thailand (three trials). Only one trial included children younger than 15 years (N = 57). We judged five trials to be at high risk of performance and detection bias owing to inadequate blinding. Trials were heterogenous in terms of dosing of interventions and outcome measures. Across trials, treatment failure rates were low. Two trials compared doxycycline to tetracycline. For treatment failure, the difference between doxycycline and tetracycline is uncertain (very low‐certainty evidence). Doxycycline compared to tetracycline may make little or no difference in resolution of fever within 48 hours (risk ratio (RR) 1.14, 95% confidence interval (CI) 0.90 to 1.44, 55 participants; one trial; low‐certainty evidence) and in time to defervescence (116 participants; one trial; low‐certainty evidence). We were unable to extract data for other outcomes. Three trials compared doxycycline versus macrolides. For most outcomes, including treatment failure, resolution of fever within 48 hours, time to defervescence, and serious adverse events, we are uncertain whether study results show a difference between doxycycline and macrolides (very low‐certainty evidence). Macrolides compared to doxycycline may make little or no difference in the proportion of patients with resolution of fever within five days (RR 1.05, 95% CI 0.99 to 1.10; 185 participants; ...

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“…Scrub typhus (Orientia tsutsugamushi), transmitted by mites in eastern and southeastern Asia, have been shown to represent up to 25% of documented acute encephalitis in some parts of India [67]. Diagnostis can be made by ELISA serology, specific microimmunofluorescence (IFA) assays using whole-cell antigens from O. tsutsugamushi serotypes, or PCR [68,69].…”

Section: Bacteriamentioning

confidence: 99%

Diagnostic approach to encephalitis and meningoencephalitis in adult returning travellers

Kenfak

Epéron

Schibler

et al. 2019

Clinical Microbiology and Infection

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a b s t r a c tBackground: Encephalitis and meningoencephalitis are severe, sometime life-threatening infections of the central nervous system. Travellers may be exposed to a variety of neurotropic pathogens. Aims: We propose to review known infectious causes of encephalitis in adults acquired outside Europe, and how to identify them. Sources: We used Pubmed and Embase, to search the most relevant publications over the last years. Content: Microbiologic tests and radiological tools to best identify the causative pathogen in travellers presenting with encephalitis and ME are presented in this narrative review, as well as a diagnostic approach tailored to the visited area and types of exposures. Implications: This review highlights the diagnostic difficulties inherent to exotic causes of central nervous system infections, and attempts to guide clinicians with respect to which microbiological tests to consider, in addition to brain MRI, when approaching a returning traveller presenting with encephalitis.

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Scrub typhus diagnosis on acute specimens using serological and molecular assays — a 3-year prospective study

Cited by 12 publications

References 43 publications

Hospitalisations and outpatient visits for undifferentiated fever attributable to scrub typhus in rural South India: Retrospective cohort and nested case-control study

Hospitalisations and outpatient visits for undifferentiated fever attributable to scrub typhus in rural South India: Retrospective cohort and nested case-control study

Antibiotics for treating scrub typhus

Diagnostic approach to encephalitis and meningoencephalitis in adult returning travellers

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