@article{fdi:010080479,
  title = {{D}iagnostic accuracy of an in-house {S}crub {T}yphus {E}nzyme linked immunoassay for the detection of {I}g{M} and {I}g{G} antibodies in {L}aos},
  author = {{E}lders, {P}. {N}. {D}. and {D}hawan, {S}. and {T}anganuchitcharnchai, {A}. and {P}hommasone, {K}. and {C}hansamouth, {V}. and {D}ay, {N}. {P}. {J}. and {G}arcia-{R}ivera, {J}. {A}. and {H}ertz, {J}. {C}. and {M}ayxay, {M}. and {V}ongsouvath, {M}. and {D}ubot {P}{\'e}r{\`e}s, {A}udrey and {R}obinson, {M}. {T}. and {N}ewton, {P}. {N}. and {B}lacksell, {S}. {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A}uthor summary {S}crub typhus is a mite-borne infectious disease, caused by the {O}rientia tsutsugamushi bacterium, resulting in considerable morbidity and mortality in the {A}sia-{P}acific region. {D}iagnosis is difficult since it does not present with any distinctive clinical signs compared to other febrile illnesses in this region, except for a necrotic skin lesion (eschar) in some patients. {L}aboratory tests are therefore crucial to identify scrub typhus. {R}eliable laboratory tests need significant infrastructure and experienced staff, making access to accurate tests very limited in the low-resource endemic regions. {T}his study aimed to evaluate the accuracy of less expensive and easier-to-use in-house {E}nzyme {L}inked {I}mmunoassays ({ELISA}s) detecting immunoglobulin {I}g{M} and {I}g{G} antibodies against scrub typhus infection compared to the "gold-standard" {I}mmunofluorescence {A}ssays ({IFA}s). {T}here was a strong positive relationship between {ELISA} and {IFA} antibody levels for both {I}g{M} and {I}g{G}. {I}f the {ELISA} would be used as a stand-alone test for scrub typhus diagnosis in {L}aos, an ideal balance between sensitivity and specificity would likely be around an {ELISA} optical density ({OD}) of 0.8-1.0 for {I}g{M} and 1.2-1.8 for {I}g{G}. {T}here is a need to investigate the use of these cut-offs in other endemic regions, which could improve the rate of scrub typhus diagnosis in low-resource settings. {S}crub typhus is a major cause of morbidity and mortality in {S}outheast {A}sia. {D}iagnosis of scrub typhus is difficult due to a lack of accessible validated diagnostic tools. {D}espite its objectivity, the diagnostic accuracy of {ELISA} tests is influenced by methodological and patient factors. {T}his study aims to evaluate the performance of a novel in-house {ELISA} developed in the {M}ahidol {O}xford {T}ropical {M}edicine {R}esearch {U}nit ({MORU}) for anti-scrub typhus group {I}g{M} and {I}g{G} compared to the "gold standard" reference {IFA} and {PCR}, and to determine whether the in-house {ELISA} can be used as a seroepidemiological screening tool and/or stand-alone test for scrub typhus. {A} total of 1,976 admission and 1,438 participant follow-up sera collected in the {L}ao {PDR} ({L}aos) were tested with {ELISA} for {I}g{M} and {I}g{G}. {S}amples with an {ELISA} {OD} >= 0.50 were tested with {IFA} for {I}g{M} and/or {I}g{G}. {A} strong positive relationship was present between {ELISA} {OD}s and {IFA} titers for admission {I}g{M} (r(2): 0.70, p <0.005) and {I}g{G} (r(2): 0.76, p<0.005), and for follow-up {I}g{M} and {I}g{G} (both r(2): 0.76, p<0.005) samples. {T}he best compromise between sensitivity and specificity for the {ELISA} {OD} cut-off is likely to be between 0.8-1.0 for {I}g{M} antibodies and 1.2-1.8 for {I}g{G} antibodies. {T}hese results demonstrate that the diagnostic accuracy of the {MORU} in-house scrub typhus group {ELISA} is comparable to that of {IFA}, with similar results as reported for the commonly used {I}n{B}ios {S}crub {T}yphus {D}etect {ELISA}, validating the use of the in-house {ELISA}. {T}he optimal {ELISA} cut-off would depend on the use of the test, and the desired sensitivity and specificity. {F}urther studies are required to authenticate the use of these cut-offs in other endemic regions. {T}his in-house {ELISA} has the potential to replace the imperfect {IFA}, which could ultimately reduce the burden of scrub typhus by improving the rate of scrub typhus diagnoses in endemic low-resource areas.},
  keywords = {{LAOS}},
  booktitle = {},
  journal = {{PL}o{S} {N}eglected {T}ropical {D}iseases},
  volume = {14},
  numero = {12},
  pages = {e0008858 [15 p.]},
  ISSN = {1935-2735},
  year = {2020},
  DOI = {10.1371/journal.pntd.0008858},
  URL = {https://www.documentation.ird.fr/hor/fdi:010080479},
}