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Journal of Clinical Microbiology, November 1998, p. 3138-3142, Vol. 36, No. 11
Fundação Oswaldo Cruz,
Received 9 March 1998/Returned for modification 14 May
1998/Accepted 4 August 1998
A commercially available slide agglutination test (SAT) for the
diagnosis of human leptospirosis was evaluated by comparing it to
an immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and
to the microscopic agglutination test (MAT). For all 108 patients,
leptospirosis was diagnosed on the basis of a fourfold or greater
increase in titer by MAT (seroconversion), and all but 1 of 245 controls were MAT negative (titers, <1:100). Both SAT and the IgM
ELISA failed to detect one case of infection (sensitivity, 99%). Only
3 of 145 blood donors and none of the 100 patients with other illnesses
were SAT positive (specificity, 99%). The overall results were similar
for the three tests; however, SAT and ELISA were statistically more
sensitive as initial screening tests. For 22% of the patients, the
diagnosis of leptospirosis was made earlier by SAT than by MAT. SAT
detected 27 (44%) of 62 MAT-negative patients with the first serum
sample. ELISA and SAT had very similar results. Follow-up of patients
for 1 year after the onset of symptoms showed a decreasing rate of
positivity by SAT from the third month on. The rate of positivity by
ELISA decreased more slowly, to about 67% by the end of the study. By MAT all patients were persistently reactive. SAT and ELISA seem to be
convenient methods for the rapid and early screening for leptospirosis
and could replace the less sensitive MAT. ELISA gives less subjective
results than SAT and provides information on IgM kinetics, but it can
be performed only by the more sophisticated laboratories. SAT is
inexpensive, can be performed more quickly and more easily than ELISA,
and could be used by the less well equipped laboratories.
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Macroscopic Agglutination Test for Rapid Diagnosis
of Human Leptospirosis
*
Corresponding author. Mailing address: Instituto Adolfo
Lutz, Av. Dr. Arnaldo 355/10° andar, Cerqueira Cesar, São
Paulo, SP, Brazil 01246-902. Phone: 55-11-30610111, ext. 2063. Fax:
55-11-8533505. E-mail: abrandao{at}plugnet.com.br.
Journal of Clinical Microbiology, November 1998, p. 3138-3142, Vol. 36, No. 11
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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