MEASLES-VACCINE - INDUCED SPECIFIC ANTIBODY IN NORMAL AND UNDERNOURISHED INFANTS

27635336

Rapid, actionable diagnosis of urban epidemic leptospirosis using a pathogenic <i>Leptospira lipL32</i>-based real-time PCR assay

<div><p>Background</p><p>With a conservatively estimated 1 million cases of leptospirosis worldwide and a 5–10% fatality rate, the rapid diagnosis of leptospirosis leading to effective clinical and public health decision making is of high importance, and yet remains a challenge.</p><p>Methodology</p><p>Based on parallel, population-based studies in two leptospirosis-endemic regions in Brazil, a real-time PCR assay which detects <i>lipL32</i>, a gene specifically present in pathogenic <i>Leptospira</i>, was assessed for the diagnostic effectiveness and accuracy. Patients identified by active hospital-based surveillance in Salvador and Curitiba during large urban leptospirosis epidemics were tested. Real-time PCR reactions were performed with DNA-extracted samples obtained from 127 confirmed and 23 unconfirmed cases suspected of leptospirosis, 122 patients with an acute febrile illness other than leptospirosis, and 60 healthy blood donors.</p><p>Principal findings</p><p>The PCR assay had a limit of detection of 280 <i>Leptospira</i> genomic equivalents/mL. Sensitivity for confirmed cases was 61% for whole blood and 29% for serum samples. Sensitivity was higher (86%) for samples collected within the first 6 days after onset of illness compared to those collected after 7 days (34%). The real-time PCR assay was able to detect leptospiral DNA in blood from 56% of serological non-confirmed cases. The overall specificity of the assay was 99%.</p><p>Conclusions</p><p>These findings indicate that real-time PCR may be a reliable tool for early diagnosis of leptospirosis, which is decisive for clinical management of severe and life-threatening cases and for public health decision making.</p></div

Positivity of the <i>lipL32</i> real-time PCR assay according to days after onset of symptoms in suspected cases of leptospirosis.

<p>The bars represent the percentage of positive whole blood samples stratified according to days with symptoms (error bars show the 95% CI). The dashed line shows the geometric mean of the reciprocal MAT titer, in accordance with days with symptoms.</p

Diagnostic performance of the real-time PCR detection assay for confirmed and unconfirmed cases of leptospirosis and control subjects.

<p>Diagnostic performance of the real-time PCR detection assay for confirmed and unconfirmed cases of leptospirosis and control subjects.</p

Standards for Reporting of Diagnostic Accuracy (STARD) flow chart of the 150 suspected leptospirosis cases enrolled in the study.

<p>Patients were selected in two Brazilian cities: Curitiba (A) and Salvador (B).</p