exhibit compatible or even better sensitivity than whole-cell-based
ELISA [11, 54–56]. These assays were evaluated in limited settings,
and their utility has not been generalized. The combination of
multiple protein antigens demonstrated an increase in sensitivity
[57], and novel protein antigens have recently been identified by
expression screening of a genomic DNA library and protein microarray analysis using patient sera [58–60].
5 Antigen Detection
The detection of leptospiral antigens in clinical specimens has not
been applied widely for the diagnosis of leptospirosis [9]. Several
leptospiral antigens have been detected in urine. Uncharacterized
35-kDa component and LigA were detected in boiled urine pellets
by monoclonal antibody (mAb)-based dot ELISA [61, 62]. Leptospiral lipopolysaccharide was detected in concentrated boiled urine
by mAb-based LFA [63]. LipL32, LipL41, Fla1, sphingomyelinases, and HbpA were detected in urine precipitates by saturated
ammonium sulfate by ELISA [64]. Leptospiral 3-hydroxyacyl-CoA
dehydrogenase was detected in concentrated urine samples by
immunoblotting [65]. Some of the studies detected antigens in
urine samples from anti-leptospiral antibody-negative patients.
6 Conclusion
The combination of diagnostic tests using appropriate specimens at
each disease stage contributes to the accurate understanding of the
burden of leptospirosis, but definitive diagnostic methods such as
isolation and MAT are not easily performed in resource-limited
settings.
The early diagnosis of leptospirosis is crucial for appropriate
treatments without delay and the improvement of patient outcomes, but it remains a challenge, especially in resource-limited
settings. The sensitivity of real-time PCR in the early stage of the
disease is up to more than 80% [22], but it is unavailable in
resource-limited peripheral health facilities. Current rapid serological tests have variable diagnostic accuracy and low sensitivity in the
early phase, which are recommended to be confirmed by MAT.
Therefore, rapid, accurate diagnostic tests for acute leptospirosis,
which are applicable in resource-limited settings, remain to be
developed.
Current reference tests, culture and MAT, are imperfect tests
[66], and the combination of diagnostic tests using appropriate
specimens at each stage should also be used for the estimation of
the diagnostic accuracy of newly developed diagnostics.
Laboratory Diagnosis of Leptospirosis
283
ELISA [11, 54–56]. These assays were evaluated in limited settings,
and their utility has not been generalized. The combination of
multiple protein antigens demonstrated an increase in sensitivity
[57], and novel protein antigens have recently been identified by
expression screening of a genomic DNA library and protein microarray analysis using patient sera [58–60].
5 Antigen Detection
The detection of leptospiral antigens in clinical specimens has not
been applied widely for the diagnosis of leptospirosis [9]. Several
leptospiral antigens have been detected in urine. Uncharacterized
35-kDa component and LigA were detected in boiled urine pellets
by monoclonal antibody (mAb)-based dot ELISA [61, 62]. Leptospiral lipopolysaccharide was detected in concentrated boiled urine
by mAb-based LFA [63]. LipL32, LipL41, Fla1, sphingomyelinases, and HbpA were detected in urine precipitates by saturated
ammonium sulfate by ELISA [64]. Leptospiral 3-hydroxyacyl-CoA
dehydrogenase was detected in concentrated urine samples by
immunoblotting [65]. Some of the studies detected antigens in
urine samples from anti-leptospiral antibody-negative patients.
6 Conclusion
The combination of diagnostic tests using appropriate specimens at
each disease stage contributes to the accurate understanding of the
burden of leptospirosis, but definitive diagnostic methods such as
isolation and MAT are not easily performed in resource-limited
settings.
The early diagnosis of leptospirosis is crucial for appropriate
treatments without delay and the improvement of patient outcomes, but it remains a challenge, especially in resource-limited
settings. The sensitivity of real-time PCR in the early stage of the
disease is up to more than 80% [22], but it is unavailable in
resource-limited peripheral health facilities. Current rapid serological tests have variable diagnostic accuracy and low sensitivity in the
early phase, which are recommended to be confirmed by MAT.
Therefore, rapid, accurate diagnostic tests for acute leptospirosis,
which are applicable in resource-limited settings, remain to be
developed.
Current reference tests, culture and MAT, are imperfect tests
[66], and the combination of diagnostic tests using appropriate
specimens at each stage should also be used for the estimation of
the diagnostic accuracy of newly developed diagnostics.
Laboratory Diagnosis of Leptospirosis
283