bmcinfectdis.biomedcentral.com Open in urlscan Pro
151.101.0.95  Public Scan

Form analysis
1 forms found in the DOM

GET //www.biomedcentral.com/search

<form role="search" class="c-form-field js-skip-validation" method="GET" action="//www.biomedcentral.com/search" data-track="submit" data-track-category="Search and Results" data-track-action="Submit search" data-dynamic-track-label=""
  data-track-label="" data-test="global-search">
  <label for="publisherSearch" class="c-form-field__label">Search all BMC articles</label>
  <div class="u-display-flex">
    <input id="publisherSearch" class="c-form-field__input" data-search-input="" autocomplete="off" role="textbox" data-test="search-input" name="query" type="text" value="">
    <div>
      <button class="u-button" type="submit" data-test="search-submit-button">
        <span class="u-visually-hidden">Search</span>
        <svg class="u-icon u-flex-static" width="16" height="16" aria-hidden="true" focusable="false">
          <use xlink:href="#icon-search"></use>
        </svg>
      </button>
    </div>
  </div>
  <input type="hidden" name="searchType" value="publisherSearch">
</form>

Text Content

YOUR PRIVACY, YOUR CHOICE

We use essential cookies to make sure the site can function. We, and our 201
partners, also use optional cookies and similar technologies for advertising,
personalisation of content, usage analysis, and social media.

By accepting optional cookies, you consent to allowing us and our partners to
store and access personal data on your device, such as browsing behaviour and
unique identifiers. Some third parties are outside of the European Economic
Area, with varying standards of data protection. See our privacy policy for more
information on the use of your personal data. Your consent choices apply to
biomedcentral.com and applicable subdomains.

You can find further information, and change your preferences via 'Manage
preferences'.
You can also change your preferences or withdraw consent at any time via 'Your
privacy choices', found in the footer of every page.

We use cookies and similar technologies for the following purposes:

STORE AND/OR ACCESS INFORMATION ON A DEVICE

Cookies, device or similar online identifiers (e.g. login-based identifiers,
randomly assigned identifiers, network based identifiers) together with other
information (e.g. browser type and information, language, screen size, supported
technologies etc.) can be stored or read on your device to recognise it each
time it connects to an app or to a website, for one or several of the purposes
presented here.

PERSONALISED ADVERTISING AND CONTENT, ADVERTISING AND CONTENT MEASUREMENT,
AUDIENCE RESEARCH AND SERVICES DEVELOPMENT

Advertising and content can be personalised based on your profile. Your activity
on this service can be used to build or improve a profile about you for
personalised advertising and content. Advertising and content performance can be
measured. Reports can be generated based on your activity and those of others.
Your activity on this service can help develop and improve products and
services.

Accept all cookies Reject optional cookies Manage preferences


Skip to main content


Advertisement



Search
 * Explore journals
 * Get published
 * About BMC
 * Login

Menu
 * Explore journals
 * Get published
 * About BMC
 * Login

Search all BMC articles
Search
BMC Infectious Diseases
 * Home
 * About
 * Articles
 * Submission Guidelines
 * Join the board
 * Collections
 * Submit manuscript


Diagnostic evaluation of IgM ELISA and IgM Immunofluorescence assay for the
diagnosis of Acute Scrub Typhus in central Nepal
Download PDF
Download PDF
 * Research article
 * Open access
 * Published: 13 February 2020


DIAGNOSTIC EVALUATION OF IGM ELISA AND IGM IMMUNOFLUORESCENCE ASSAY FOR THE
DIAGNOSIS OF ACUTE SCRUB TYPHUS IN CENTRAL NEPAL

 * Rajendra Gautam1,
 * Keshab Parajuli1,
 * Tshokey Tshokey2,
 * John Stenos2 &
 * …
 * Jeevan Bahadur Sherchand1 

Show authors

BMC Infectious Diseases volume 20, Article number: 138 (2020) Cite this article

 * 7093 Accesses

 * 15 Citations

 * Metrics details


ABSTRACT


BACKGROUND

Scrub typhus is an acute febrile illness caused by the obligate intracellular
bacterium, Orientia tsutsugamushi. Immunochromatography (ICT) and IgM ELISA are
two of the routinely employed antibody based assays for diagnosis of Scrub
typhus fever in Nepal, although the recommended gold standard diagnostic test is
IgM Immunofluorescence assay (IFA). This study evaluated InBios Scrub Typhus
Detect™ Immunoglobulin M (IgM) ELISA and IgM Immunofluorescence assays in single
serum sample at the time of admission.


METHOD

Study participants (1585 suspected cases), were enrolled based on acute febrile
illness with suspected scrub typhus cases in central Nepal. Blood sample was
collected from the suspected patients of scrub typhus, presenting with acute
febrile illness. IgM antibody to Orientia tsusugamushi was detected by using
Scrub Typhus Detect™ Kit and an in-house IgM IFA. The IFA assay was performed
with the Gilliam, Karp, Kato strains and O. chuto antigens following the ARRL
protocol.


RESULT

Statistical analysis of IgM ELISA results when compared to reference test, IgM
IFA results demonstrated the following characteristics, sensitivity 84.0%
(95%CI: 79.73–87.68%), specificity 94.82% (95% CI: 93.43–95.99%), positive
likelihood ratio 16.21% (95% CI: 12.71–20.67%), negative likelihood ratio 0.17%
(95% CI: 0.13–0.21%), disease prevalence 22.08% (95% CI: 20.06 -24.21%),
positive predictive value 82.12% (95% CI: 78.28–85.42%) and negative predictive
value 95.44% (95% CI: 94.27–96.38%) respectively.


CONCLUSION

Although IgM IFA is considered the gold standard test for the diagnosis of scrub
typhus cases, it is relatively expensive, requires trained personal and a
microscope with fluorescence filters. Scrub typhus IgM ELISA may be the best
alternative test and possible viable option for resource limited endemic
countries like Nepal.

Peer Review reports


BACKGROUND

Scrub typhus is an acute febrile illness caused by the obligate intracellular
bacteria Orientia tsutsugamushi. Scrub typhus is an arthropod-borne illness with
the larval stage of several species of trombiculid mites called as chiggers; act
as vectors for the transmission of the disease to the human beings. The species
of the genus Leptotrombidium, particularly leptotrombidium deliense is
considered to be primary cause of disease transmission in most countries [1].
Humans become infected with Orientia tsutsugamushi via the bite of an infected
chigger, which act as both the vector and reservoir of Orientia tsutsugamushi.

Traditionally, the scrub typhus was considered to be endemic in the part of
world described by ‘tsutsugamushi triangle’ which consists the northern most
point in Korea, Japan and the far eastern Russia in the north, reaching to
tropical northern Australia in the south and Pakistan and Afghanistan in the
west [2]. However, in recent years, serological evidence shows its presence
outside the tsutsugamushi triangle [3].

Nepal is considered as an endemic area of tsutsugamushi triangle and the
outbreak of this disease is reported from different districts [4]. Early
detection is difficult due to similarity of symptoms with other acute febrile
illness such as malaria, dengue, leptospirosis, viral hemorrhagic fevers and
enteric fever. Rapid and accurate diagnosis is essential for proper treatment
and prevention of lethal complications. Various serological methods are
available for the diagnosis of scrub typhus such as Weil-Felix test,
Immunochromatographic test (ICT), Enzyme linked immunosorbent assay (ELISA),
Immunofluorescence assay (IFA), Indirect immunoperoxidase assay. Molecular
techniques (Real time and conventional PCR) and isolation of the organism O.
tsutsugamushi from blood and eschar of the patient are also utilized, however
culture is not commonly utilised.

Antibody based diagnostic assays are important for the diagnosis of scrub typhus
in resource limited countries like Nepal. Although the gold standard test for
diagnosis of acute scrub typhus is IgM IFA [5, 6], ICT and IgM ELISA are
routinely employed in Nepal. The scrub typhus IgM ELISA was first developed
after the purification of the antigens derived from the host cells [7]. An assay
utilizing the O. tsutsugamushi-specific recombinant 56-kDa antigen is now
available as a commercial ELISA kit.

Despite the wide use of ICT and IgM ELISA, data on their performance and
efficacy in resource limited countries like Nepal, is not widely available.
Hence this study was designed to evaluate the performance of the ELISA in
comparison with an in-house IgM IFA in an acute serum sample taken at the time
of admission.


METHODS


SAMPLES

A prospective study was conducted among hospitalized acute febrile illness
patients with suspected scrub typhus in central Nepal for a period of one year,
April 2017 to March 2018. Cases of uncharacterized acute fever for more than
4 days were included in the study after excluding the confirmed cases of other
febrile illness caused by malaria, dengue, leptospirosis, and enteric fever.
Single blood sample were collected from this subset of acute febrile illness
patients that were hospitalized. The blood samples were centrifuged at 3000 rpm
for 5 min to separate the serum. Serum samples were stored at − 80 °C until they
were analyzed.


SCRUB TYPHUS DETECT™ IGM ELISA

IgM antibody to Orientia tsutsugamushi was detected by using Scrub Typhus
Detect™ Kit, InBios International, USA containing the recombinant p56kDa type
specific antigens of Orientia tsutsugamushi Karp, Kato, Gilliam and TA 716
strains according to the manufacturer’s instruction. Optical density was
measured by HumaReader HS, ELISA reader, optical densities (ODs) > 0.50 was
considered positive. The cut-off was calculated following recommendations for
determining the endemic cut-off titre in the kit protocol. The cut-off
calculated from healthy volunteer was mean OD (0.23) + 3 standard deviation
(0.09) =0.50. We proposed a cut-off OD value of > 0.50 for chitwan and
surrounding region based on our finding.


IGM IMMUNOFLUORESCENCE ASSAY

Antibodies against Scrub Typhus Group were tested using Orientia tsutsugamushi
(Gilliam, Karp, Kato) strains and Orientia chuto antigens. The antigens were
prepared in the Australian Rickettsial Reference Laboratory, Geelong, Australia
by culturing the organism in L929 cell line and RPMI media (Invitrogen)
supplemented with 5% fetal bovine serum. Individual antigens were coated onto
rickettsial screening slides containing 40 individual wells, air dried and fixed
in acetone. Serum samples were diluted 1:128 in 2% casein buffer and spotted
onto the slide in duplicate and incubated at 37 °C for 40 min in a moist chamber
to allow for the binding of antigen and antibody. With each slide tested,
positive and negative controls were included. Slides were washed 3 times in PBS
and dried. An anti-human FITC labeled IgM conjugate was then added and slides
incubated at 37 °C for 40 min in a moist chamber. Slides were washed once more,
air dried, mounted and observed under the fluorescent microscope. Positive
results are indicated when fluorescence intensity was equal to or greater than
the positive control. The diagnostic cutoff > 1:128 was considered positive
which was derived after testing the serum samples of healthy controls from that
particular region. Negative results were reported when the sera didn’t fluoresce
at a dilution of 1:128. Positive serum samples were serially titrated 1:128,
1:256, 1:512, 1:1024, 1:2048, 1:4096, 1:8192, 1:16384 etc. to end point titers
with individual antigens.


QUALITY CONTROL

Positive and negative controls were included with each slide that if either
failed in a screening or titration slide, tests were repeated. In instances of
continuation of assay failure both the antibody and antigen controls were
re-titrated to see if there had been a shift in the antibody endpoint or if the
antigen had lost its reactivity. Whenever necessary fresh controls and antigens
were optimised prior to repeating of the assay with the specimens.


STATISTICAL ANALYSIS

The collected data were entered in Epi info 3.5 from CDC and exported to IBM
SPSS version 16.0 (SPSS Inc. Chicago, USA). The sensitivities, specificities,
positive predictive values, negative predictive values of the serological tests
were calculated using MedCalc for windows, version 18.11.3 (MedCalc, Software,
Ostend, Belgium). STARD 2015 guidelines for reporting diagnostic accuracy
studies was strictly followed [8].


RESULTS

Standard for Reporting Diagnostic Accuracy (STARD) flow chart of suspected scrub
typhus cases enrolled in the study is given in Fig. 1. Out of clinically
suspected 1585 cases 358 (22.58%) were IgM ELISA positive, OD Values for
Orientia tsutsugamushi IgM ELISA Positive samples are summarized in Fig. 2, of
these 294 were also positive by IgM IFA. Among these 358 IgM ELISA positives,
the mean age of the patients was 29.7 years with female preponderance (61.7%),
fever was the most common (100%) clinical characteristic followed by nausea
(50.6%) with thrombocytopenia in 74.09%, presence of eschar was observed in 3.1%
patients. The median number of days of fever prior to hospitalization was 7. The
IgM IFA endpoint titers for Orientia tsutsugamushi antigens IgM ELISA positive
samples are listed in Fig. 3. Among the 1227 IgM ELISA negative samples 56 were
positive by IgM IFA. Comparison of IgM ELISA and IgM IFA results are summarized
in Table 1.

Fig. 1

Standard for Reporting Diagnostic Accuracy (STARD) Flow Chart of the suspected
Scrub typhus cases enrolled in the study

Full size image
Fig. 2

OD Values for Orientia tsutsugamushi IgM ELISA Positive samples (n=358)

Full size image
Fig. 3

IgM IFA reciprocal titer for orientia tsutsugamushi IgM ELISA positive samples
(n = 358)

Full size image
Table 1 Comparison of IgM ELISA and IgM IFA test (n = 1585)
Full size table

Statistical analysis of ELISA IgM results when compare to IgM IFA results
demonstrated the following characteristics, sensitivity 84.0% (95% CI:
79.73–87.68%), specificity 94.82% (95% CI: 93.43–95.99%), positive likelihood
ratio 16.21% (95% CI: 12.71–20.67%), negative likelihood ratio 0.17% (95% CI:
0.13–0.21%), disease prevalence 22.08% (95% CI: 20.06 -24.21%), positive
predictive value 82.12% (95% CI: 78.28–85.42%), negative predictive value 95.44%
(95% CI: 94.27–96.38%) respectively. Calculation of statistical values of IgM
ELISA test compared with IgM IFA are summarized in Table 2.

Table 2 Calculation of statistical value of IgM ELISA test compared with IgM
Immunofluorescence test
Full size table


DISCUSSION

Scrub typhus is an endemic/reemerging acute febrile infectious disease prevalent
in Nepal. The diagnosis of scrub typhus was generally done by clinical
presentation and history reporting prior to its serological diagnosis. The
common clinical manifestations of other acute febrile illness make it difficult
for its clinical diagnosis. The mortality rate varies from 0 to 30% if left
untreated in the endemic areas [9].

In this study we compared the results of the Scrub Typhus Detect™ IgM ELISA
against the gold standard IgM IFA.

The overall sensitivity and specificity of the IgM ELISA was 84.0% (95% CI:
79.73–87.68%) and 94.82% (CI: 93.43–95.99%) respectively in our study. Various
studies have demonstrated a similar performance, with sensitivities in the range
of 85 to 93% and specificities 94 to 97.5% [10,11,12].The diagnostic cut-off OD
in this study varied from > 0.50–7.50. Sensitivity of IgM ELISAs varies from 70
to 100% according to various scientific reports [13,14,15].

InBios IgM ELISA is a sensitive and specific test and could be substitute for
the IgM IFA in resource limited countries like Nepal. ELISA is comparatively
cheaper and easier test with high throughput of the specimens.

Indirect immunofluorescence assay (IFA) is considered to be the gold standard
test for the diagnosis of scrub typhus [16], in which the patients serum
containing the antibodies to Orientia tsutsugamushi are mixed to antigen on a
slide, then detected using a fluorescently labeled anti-human antibody. Karp,
Kato and Gilliam serotypes are the most commonly used antigens [16], local
serotypes are also included in some area [17]. Among 1585 samples 350 (22.08%)
were positive IgM IFA in our study. End point titer ranged from
> 1:128–1:524,288. High titer observed in our study may be due to active phase
of the disease. The sensitivity of IFA varies from 70 to 100% and specificity
varies from 84 to 100% according to the various scientific publications [11, 14,
15]. Diagnostic cut-off titers of IFA vary from 1:10–1:400, which may lead to
confusion in its use in the endemic area [16].

Local cut off titer must be determined in the endemic countries based on the
seroprevalence rate in the healthy population while using IFA and ELISA, which
enables to distinguish the acute infection and previous exposure if only single
serum sample is available [16]. Although IFA is loosely considered the gold
standard diagnostic test, it is an imperfect reference test, particularly when
using only acute samples for diagnosis. IFA has additional limitations as this
depends on the microscopist who reads the slides and determines the end-point
titer. There might be inter- and intra-operator variability so microscopists
must be supervised by more experienced laboratory professional and undergo
several months of training before their results can be considered reliable [18].
Requirements of a trained personal, fluorescent microscope, validation of
appropriate diagnostic cut offs and relatively high cost is the main drawback of
the IFA. Even with all these negatives, IFA stands out as a far superior test in
scrub typhus diagnosis.

The various limitations of this study include the collection of single serum
specimens for the detection of IgM antibodies during the acute phase of the
disease. A rise in the antibody titer in paired sera could not be detected in
our study. The circulating strains of Orientia species in Nepal are not known so
antigens used in the serological assays Orientia tsutsugamushi Karp, Kato,
Gilliam, TA 716 and Orientia chuto may not be representative of the infecting
Orientia from this region which may lead to lower sensitivity of both ELISA and
IFA used. The antigens used for ELISA test (TA716) and IFA (O. Chuto) may lead
to minor inaccuracies in the result and validation between the IFA and ELISA.


CONCLUSION

Scrub typhus is the common acute febrile illness present in our country Nepal.
Although IgM IFA is considered the gold standard test for the diagnosis of scrub
typhus cases, it requires trained personal and fluorescent microscope. IFA is
gold standard test which need to be utilized for all research purposes. It may
be difficult to use this method for the routine diagnosis of scrub typhus in
resource limited countries. Scrub typhus IgM ELISA may be the best alternative
test for routine use currently available in Nepal.


AVAILABILITY OF DATA AND MATERIALS

All authors had full access to the data and materials. Data are available within
this article. Detailed data is available from the corresponding author upon
reasonable request.


ABBREVIATIONS

ARRL:

Australian Rickettsial Reference Laboratory

ELISA:

Enzyme Linked Immunosorbent Assay

ICT:

Immunochromatography

IFA:

Immunofluorescence assay

IgM:

Immunoglobulin M


REFERENCES

 1.  Lee HI, Shim SK, Song BG, Choi EN, Hwang KJ, Park MY, Park C, Shin E-H.
     Detection of Orientia tsutsugamushi, the causative agent of scrub typhus,
     in a novel mite species, Eushoengastia koreaensis, in Korea. Vector Borne
     Zoonotic Dis. 2011;11(3):209–14.
     
     Article  Google Scholar 

 2.  Paris DH, Shelite TR, Day NP, Walker DH. Unresolved problems related to
     scrub typhus: a seriously neglected life-threatening disease. Am J Trop Med
     Hyg. 2013;89(2):301–7.
     
     Article  Google Scholar 

 3.  Jiang J, Richards A. Scrub typhus: no longer restricted to the
     Tsutsugamushi triangle. Trop Med Infect Dis. 2018;3(1):11.
     
     Article  Google Scholar 

 4.  Upadhayay B, Shakya G, Adhikari S, Rijal N, Acharya J, Maharjan L, Marasini
     B. Scrub typhus: an emerging neglected tropical disease in Nepal. J Nepal
     Health Res Counc. 2016.

 5.  Pradutkanchana J, Silpapojakul K, Paxton H, Pradutkanchana S, Kelly DJ,
     Strickman D. Comparative evaluation of four serodiagnostic tests for scrub
     typhus in Thailand. Trans R Soc Trop Med Hyg. 1997;91(4):425–8.
     
     Article  CAS  Google Scholar 

 6.  La Scola B, Raoult D. Laboratory diagnosis of rickettsioses: current
     approaches to diagnosis of old and new rickettsial diseases. J Clin
     Microbiol. 1997;35(11):2715.
     
     Article  Google Scholar 

 7.  Dasch GA, Halle S, Bourgeois AL. Sensitive microplate enzyme-linked
     immunosorbent assay for detection of antibodies against the scrub typhus
     rickettsia, rickettsia tsutsugamushi. J Clin Microbiol. 1979;9(1):38–48.
     
     CAS  PubMed  PubMed Central  Google Scholar 

 8.  Cohen JF, Korevaar DA, Altman DG, Bruns DE, Gatsonis CA, Hooft L, Irwig L,
     Levine D, Reitsma JB, De Vet HC. STARD 2015 guidelines for reporting
     diagnostic accuracy studies: explanation and elaboration. BMJ Open.
     2016;6(11):e012799.
     
     Article  Google Scholar 

 9.  Lee Y-M, Kim D-M, Lee S-H, Jang M-S, Neupane GP. Phylogenetic analysis of
     the 56 kDa protein genes of Orientia tsutsugamushi in southwest area of
     Korea. Am J Trop Med Hyg. 2011;84(2):250–4.
     
     Article  CAS  Google Scholar 

 10. Koraluru M, Bairy I, Varma M, Vidyasagar S. Diagnostic validation of
     selected serological tests for detecting scrub typhus. Microbiol Immunol.
     2015;59(7):371–4.
     
     Article  CAS  Google Scholar 

 11. Coleman RE, Sangkasuwan V, Suwanabun N, Eamsila C, Mungviriya S, Devine P,
     Richards AL, Rowland D, Ching W-M, Sattabongkot J. Comparative evaluation
     of selected diagnostic assays for the detection of IgG and IgM antibody to
     Orientia tsutsugamushi in Thailand. Am J Trop Med Hyg. 2002;67(5):497–503.
     
     Article  CAS  Google Scholar 

 12. Prakash J, Abraham O, Mathai E. Evaluation of tests for serological
     diagnosis of scrub typhus. Trop Dr. 2006;36(4):212–3.
     
     Article  CAS  Google Scholar 

 13. Paris DH, Dumler JS. State of the art of diagnosis of rickettsial diseases:
     the use of blood specimens for diagnosis of scrub typhus, spotted fever
     group rickettsiosis, and murine typhus. Curr Opin Infect Dis.
     2016;29(5):433.
     
     Article  CAS  Google Scholar 

 14. Lim C, Paris DH, Blacksell SD, Laongnualpanich A, Kantipong P, Chierakul W,
     Wuthiekanun V, Day NP, Cooper BS, Limmathurotsakul D. How to determine the
     accuracy of an alternative diagnostic test when it is actually better than
     the reference tests: a re-evaluation of diagnostic tests for scrub typhus
     using Bayesian LCMs. PLoS One. 2015;10(5):e0114930.
     
     Article  Google Scholar 

 15. Kim Y-J, Yeo S-J, Park S-J, Woo Y-J, Kim M-W, Kim S-H, Chang I, Jeon S-H,
     Park B-J, Song G-J. Improvement of the diagnostic sensitivity of scrub
     typhus using a mixture of recombinant antigens derived from Orientia
     tsutsugamushi serotypes. J Korean Med Sci. 2013;28(5):672–9.
     
     Article  CAS  Google Scholar 

 16. Blacksell SD, Bryant NJ, Paris DH, Doust JA, Sakoda Y, Day NP. Scrub typhus
     serologic testing with the indirect immunofluorescence method as a
     diagnostic gold standard: a lack of consensus leads to a lot of confusion.
     Clin Infect Dis. 2007;44(3):391–401.
     
     Article  Google Scholar 

 17. Koh GC, Maude RJ, Paris DH, Newton PN, Blacksell SD. Diagnosis of scrub
     typhus. Am J Trop Med Hyg. 2010;82(3):368–70.
     
     Article  Google Scholar 

 18. Phetsouvanh R, Thojaikong T, Phoumin P, Sibounheuang B, Phommasone K,
     Chansamouth V, Lee SJ, Newton PN, Blacksell SD. Inter-and intra-operator
     variability in the reading of indirect immunofluorescence assays for the
     serological diagnosis of scrub typhus and murine typhus. Am J Trop Med Hyg.
     2013;88(5):932–6.
     
     Article  CAS  Google Scholar 

Download references


ACKNOWLEDGEMENTS

We would like to acknowledge the faculty members from the Department of
Microbiology, Maharajgunj Medical Campus, Institute of Medicine and all the
staff of the Australian Rickettsial Reference Laboratory, Geelong, Victoria,
Australia.


FUNDING

This work was partially supported by University Grant Commission (Award No:PhD
073/74/HS-01) and the Australian Rickettsial Reference Laboratory.


AUTHOR INFORMATION


AUTHORS AND AFFILIATIONS

 1. Department of Microbiology, Maharajgunj Medical Campus, Institute of
    Medicine, Kathmandu, Nepal
    
    Rajendra Gautam, Keshab Parajuli & Jeevan Bahadur Sherchand

 2. Australian rickettsial reference laboratory, Geelong, Victoria, Australia
    
    Tshokey Tshokey & John Stenos

Authors
 1. Rajendra Gautam
    View author publications
    
    You can also search for this author in PubMed Google Scholar

 2. Keshab Parajuli
    View author publications
    
    You can also search for this author in PubMed Google Scholar

 3. Tshokey Tshokey
    View author publications
    
    You can also search for this author in PubMed Google Scholar

 4. John Stenos
    View author publications
    
    You can also search for this author in PubMed Google Scholar

 5. Jeevan Bahadur Sherchand
    View author publications
    
    You can also search for this author in PubMed Google Scholar


CONTRIBUTIONS

RG, KP and JBS conceived and designed the experiments, JS reviewed the proposal
and experiments; RG and TT performed the experiments; JS and TT administered and
supervised the work; RG analyzed the data and wrote the first draft of the
paper; KP, JBS, TT and JS reviewed and corrected the paper. All authors reviewed
and approved the manuscript.


CORRESPONDING AUTHOR

Correspondence to Rajendra Gautam.


ETHICS DECLARATIONS


ETHICS APPROVAL AND CONSENT TO PARTICIPATE

Ethical approval was obtained from the institutional review board of Institute
of Medicine, Tribhuvan University, Kathmandu, Nepal (Ref: 331/073/074). Written
inform consent was obtained from all the participants prior to their enrollment
in the study.


CONSENT FOR PUBLICATION

Not applicable since there are no details, images, or videos relating to an
individual person.


COMPETING INTERESTS

All other authors declare that they have no competing interests.


ADDITIONAL INFORMATION


PUBLISHER’S NOTE

Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.


RIGHTS AND PERMISSIONS

Open Access This article is distributed under the terms of the Creative Commons
Attribution 4.0 International License
(http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided you give appropriate
credit to the original author(s) and the source, provide a link to the Creative
Commons license, and indicate if changes were made. The Creative Commons Public
Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/)
applies to the data made available in this article, unless otherwise stated.

Reprints and permissions


ABOUT THIS ARTICLE


CITE THIS ARTICLE

Gautam, R., Parajuli, K., Tshokey, T. et al. Diagnostic evaluation of IgM ELISA
and IgM Immunofluorescence assay for the diagnosis of Acute Scrub Typhus in
central Nepal. BMC Infect Dis 20, 138 (2020).
https://doi.org/10.1186/s12879-020-4861-y

Download citation

 * Received: 22 May 2019

 * Accepted: 06 February 2020

 * Published: 13 February 2020

 * DOI: https://doi.org/10.1186/s12879-020-4861-y


SHARE THIS ARTICLE

Anyone you share the following link with will be able to read this content:

Get shareable link

Sorry, a shareable link is not currently available for this article.



Copy to clipboard

Provided by the Springer Nature SharedIt content-sharing initiative


KEYWORDS

 * Scrub typhus
 * ELISA
 * Orientia tsutsugamushi
 * Nepal


Download PDF
 * Sections
 * Figures
 * References

 * Abstract
 * Background
 * Methods
 * Results
 * Discussion
 * Conclusion
 * Availability of data and materials
 * Abbreviations
 * References
 * Acknowledgements
 * Funding
 * Author information
 * Ethics declarations
 * Additional information
 * Rights and permissions
 * About this article

Advertisement


 * Fig. 1
   
   View in articleFull size image

 * Fig. 2
   
   View in articleFull size image

 * Fig. 3
   
   View in articleFull size image

 1.  Lee HI, Shim SK, Song BG, Choi EN, Hwang KJ, Park MY, Park C, Shin E-H.
     Detection of Orientia tsutsugamushi, the causative agent of scrub typhus,
     in a novel mite species, Eushoengastia koreaensis, in Korea. Vector Borne
     Zoonotic Dis. 2011;11(3):209–14.
     
     Article  Google Scholar 

 2.  Paris DH, Shelite TR, Day NP, Walker DH. Unresolved problems related to
     scrub typhus: a seriously neglected life-threatening disease. Am J Trop Med
     Hyg. 2013;89(2):301–7.
     
     Article  Google Scholar 

 3.  Jiang J, Richards A. Scrub typhus: no longer restricted to the
     Tsutsugamushi triangle. Trop Med Infect Dis. 2018;3(1):11.
     
     Article  Google Scholar 

 4.  Upadhayay B, Shakya G, Adhikari S, Rijal N, Acharya J, Maharjan L, Marasini
     B. Scrub typhus: an emerging neglected tropical disease in Nepal. J Nepal
     Health Res Counc. 2016.

 5.  Pradutkanchana J, Silpapojakul K, Paxton H, Pradutkanchana S, Kelly DJ,
     Strickman D. Comparative evaluation of four serodiagnostic tests for scrub
     typhus in Thailand. Trans R Soc Trop Med Hyg. 1997;91(4):425–8.
     
     Article CAS  Google Scholar 

 6.  La Scola B, Raoult D. Laboratory diagnosis of rickettsioses: current
     approaches to diagnosis of old and new rickettsial diseases. J Clin
     Microbiol. 1997;35(11):2715.
     
     Article  Google Scholar 

 7.  Dasch GA, Halle S, Bourgeois AL. Sensitive microplate enzyme-linked
     immunosorbent assay for detection of antibodies against the scrub typhus
     rickettsia, rickettsia tsutsugamushi. J Clin Microbiol. 1979;9(1):38–48.
     
     CAS PubMed PubMed Central  Google Scholar 

 8.  Cohen JF, Korevaar DA, Altman DG, Bruns DE, Gatsonis CA, Hooft L, Irwig L,
     Levine D, Reitsma JB, De Vet HC. STARD 2015 guidelines for reporting
     diagnostic accuracy studies: explanation and elaboration. BMJ Open.
     2016;6(11):e012799.
     
     Article  Google Scholar 

 9.  Lee Y-M, Kim D-M, Lee S-H, Jang M-S, Neupane GP. Phylogenetic analysis of
     the 56 kDa protein genes of Orientia tsutsugamushi in southwest area of
     Korea. Am J Trop Med Hyg. 2011;84(2):250–4.
     
     Article CAS  Google Scholar 

 10. Koraluru M, Bairy I, Varma M, Vidyasagar S. Diagnostic validation of
     selected serological tests for detecting scrub typhus. Microbiol Immunol.
     2015;59(7):371–4.
     
     Article CAS  Google Scholar 

 11. Coleman RE, Sangkasuwan V, Suwanabun N, Eamsila C, Mungviriya S, Devine P,
     Richards AL, Rowland D, Ching W-M, Sattabongkot J. Comparative evaluation
     of selected diagnostic assays for the detection of IgG and IgM antibody to
     Orientia tsutsugamushi in Thailand. Am J Trop Med Hyg. 2002;67(5):497–503.
     
     Article CAS  Google Scholar 

 12. Prakash J, Abraham O, Mathai E. Evaluation of tests for serological
     diagnosis of scrub typhus. Trop Dr. 2006;36(4):212–3.
     
     Article CAS  Google Scholar 

 13. Paris DH, Dumler JS. State of the art of diagnosis of rickettsial diseases:
     the use of blood specimens for diagnosis of scrub typhus, spotted fever
     group rickettsiosis, and murine typhus. Curr Opin Infect Dis.
     2016;29(5):433.
     
     Article CAS  Google Scholar 

 14. Lim C, Paris DH, Blacksell SD, Laongnualpanich A, Kantipong P, Chierakul W,
     Wuthiekanun V, Day NP, Cooper BS, Limmathurotsakul D. How to determine the
     accuracy of an alternative diagnostic test when it is actually better than
     the reference tests: a re-evaluation of diagnostic tests for scrub typhus
     using Bayesian LCMs. PLoS One. 2015;10(5):e0114930.
     
     Article  Google Scholar 

 15. Kim Y-J, Yeo S-J, Park S-J, Woo Y-J, Kim M-W, Kim S-H, Chang I, Jeon S-H,
     Park B-J, Song G-J. Improvement of the diagnostic sensitivity of scrub
     typhus using a mixture of recombinant antigens derived from Orientia
     tsutsugamushi serotypes. J Korean Med Sci. 2013;28(5):672–9.
     
     Article CAS  Google Scholar 

 16. Blacksell SD, Bryant NJ, Paris DH, Doust JA, Sakoda Y, Day NP. Scrub typhus
     serologic testing with the indirect immunofluorescence method as a
     diagnostic gold standard: a lack of consensus leads to a lot of confusion.
     Clin Infect Dis. 2007;44(3):391–401.
     
     Article  Google Scholar 

 17. Koh GC, Maude RJ, Paris DH, Newton PN, Blacksell SD. Diagnosis of scrub
     typhus. Am J Trop Med Hyg. 2010;82(3):368–70.
     
     Article  Google Scholar 

 18. Phetsouvanh R, Thojaikong T, Phoumin P, Sibounheuang B, Phommasone K,
     Chansamouth V, Lee SJ, Newton PN, Blacksell SD. Inter-and intra-operator
     variability in the reading of indirect immunofluorescence assays for the
     serological diagnosis of scrub typhus and murine typhus. Am J Trop Med Hyg.
     2013;88(5):932–6.
     
     Article CAS  Google Scholar 

BMC INFECTIOUS DISEASES

ISSN: 1471-2334

CONTACT US

 * Submission enquiries: bmcinfectiousdiseases@biomedcentral.com
 * General enquiries: ORSupport@springernature.com

 * Read more on our blogs
 * Receive BMC newsletters
 * Manage article alerts
 * Language editing for authors
 * Scientific editing for authors

 * Policies
 * Accessibility
 * Press center

 * Support and Contact
 * Leave feedback
 * Careers


FOLLOW BMC

 * BMC Twitter page
 * BMC Facebook page
 * BMC Weibo page

By using this website, you agree to our Terms and Conditions, Your US state
privacy rights, Privacy statement and Cookies policy. Your privacy
choices/Manage cookies we use in the preference centre.

© 2024 BioMed Central Ltd unless otherwise stated. Part of Springer Nature.