prospective evaluation of three rapid diagnostic tests for diagnosis of human leptospirosis.ppt

7/21/2019 Prospective Evaluation of Three Rapid Diagnostic Tests for Diagnosis of Human Leptospirosis.ppt

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Rio Gusta Notario

Journal Reading tropic Infection department


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Leptospirosis is caused by microorganisms of thegenus Leptospira

It causes an acute febrile illness with a widediversity of milder clinical signs such headache

Malaise

Myalgia

conjunctival suusion

transient rash

The most commonly used laboratory tests arebased on detection of antibodies against theleptospires


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fter infection leptospires circulate in theblood stream! with a bacteremic phase

lasting for up to "# days post onset of thedisease $%&'(

These antibodies can be detected by a

variety of laboratory assays such as ) the microscopic agglutination test $MT(

en*yme+lin,ed immunosorbent assay $-LI.(

Indirect /uorescent antibody test $I0T(


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%uring the "" years of data collection! bloodspecimens from

1232 participants suspected of leptospirosiswere submitted to NRL for testing4 The majority of participants

$31456( were tested by MT! IgM -LI. and

one or more of the rapid tests


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%ata analyses %ata were entered into a Laboratory Information

.ystem $L..I.T! Mechatronics .oftware pplications78! the Netherlands( and e9ported and analy*ed in.&.. $version "3! I7M! N:!;.(

'verall accuracy the overall accuracy of R%Ts for diagnosing

leptospirosis for any submitted sample wasestimated

'verall accuracy < 0irst sample sent in andfollow+up sample To avoid potential overestimations of sensitivity and

underestimations of speci=city of the individual test in theabove analyses! a subgroup analysis was completed on onlythe =rst sample that was sent in! and! if available! on thefollow+up sample $paired samples(! if ta,en within " month


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There were 2>? $>4?6( leptospirosis casesful=lling the case de=nition! with a male tofemale se9 ratio of about >)"4

The se9 ratio of non+leptospirosis cases was@)"4 The mean age of cases and non+caseswas 234? and 5@4" years! respectively4

Male leptospirosis cases were older $mean age5#4@! .% "14?( than female cases $mean age2>4A! .% "?42(

R%Ts were performed on "st and follow+upspecimens from A>"B3@3 participants $">4?6

of all participants(C A#4?6 of the leptospirosiscases! and ""4A6 of the non+leptospirosisparticipants4


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The overall sensitivity and speci=city!calculated on all samples from early acute tillthe late convalescent phase showed sensitivity of ?16 $316 DI >36 to ?36( for

LeptoTe, %ri %ot! ?A6 $316 DI >36 to A16( for LeptoTe, Lateral 0low

?A6 $316 DI ?"6 to A26( for Leptochec,+E74 Thespeci=city was

3>6 $316 DI 316 to 3?6( for LeptoTe, %ri %ot!

316 $316 DI 356 to 3>6( for LeptoTe, Lateral 0low

3A6 $316 DI 3?6 to 3A6( for Leptochec,+E7


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bout @A6 of the participants with an initialindeterminate

positive R%T compared to only "#6 ofparticipants with an initial negative result40or the LeptoTe, Lateral 0low!the numbersare somewhat dierent

with 36 positive results after the =rst sample wasindeterminate

56 positive results after the =rst sample wasnegative! but the same trend is present


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This paper presents data of a prospective evaluationof three R%Ts for leptospirosis! the LeptoTe, %ri %ot!the LeptoTe, Lateral 0low and the Leptochec,+E7

The overall sensitivity and speci=city did not vary

much between the tests! with sensitivity rangingfrom ?16 to ?A6 and speci=city ranging from 31 to3A6

The sensitivity of the LeptoTe, %ri %ot and theLeptochec,+E7 was mar,edly lower! i4e4 1"6 and

116! respectively while the sensitivity of theLeptoTe, Lateral 0low test dropped less to a stillappreciable >364


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Dlinically this indicates that with around 1##suspected cases annually received at theNRL! comprising appro9imately 2#con=rmed leptospirosis cases

It should be pointed out that in mostsituations! where leptospirosis is highly

endemic! availability of only one acutephase sample is common practice hence! the diagnostic accuracy of tests on

early acute samples is most relevant

This higher sensitivity in the early acutephase cannot be e9plained by the choice ofantigen! which is most li,ely similar!


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ll R%Ts showed a lower speci=city whentesting paired samples compared to the "st

submitted sample only ll R%Ts showed a lower speci=city when

testing paired samples compared to the "stsubmitted sample only

n une9pected high percentage ofindeterminate results were found!considering the fact that the reading of theR%Ts was done on a daily basis by a small

group of well+e9perienced sta4 Thisindicates that these tests are not alwayseasily read


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0rom the additional diagnostic accuracy ofthe R%Ts by infecting serogroup! thesensitivity of all three R%Ts was higher forinfection with the Icterohaemorrhagiaegroup compared to infections with otherserogroups


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The LeptoTeF Lateral 0low presents in allscenarios with the best sensitivity andeually good speci=city of all three R%T tests4

ll three tests! LeptoTe, %ri %ot! LeptoTe,

Lateral 0low and Leptochec,+E7 presentuseful antibody tests contributing to thediagnosis of leptospirosis

0or sure! con=rmation of clinical suspicion will

contribute to increased local awareness ofleptospirosis


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prospective evaluation of three rapid diagnostic tests for diagnosis of human leptospirosis.ppt

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