Diagnosis of Giardia infections by PCR-based methods in children of an endemic area

David EB (1), Coradi ST (2), Oliveira-Sequeira TCG (1), Ribolla PEM (1), Katagiri S (1), Guimarães S (1)

(1) Department of Parasitology, Botucatu Biosciences Institute, São Paulo State University (UNESP - Univ Estadual Paulista), Botucatu, São Paulo State, Brazil; (2) Department of Biological and Health Sciences, Sacred Heart University, USC, Bauru, São Paulo State, Brazil.

Abstract: The present study was designed to estimate the prevalence of Giardia infection in preschool- and school-aged children living in an endemic area. Fecal samples from 573 children were processed by zinc sulfate centrifugal flotation, centrifugal sedimentation (using a commercial device for fecal concentration - TF-Test kit®) and polymerase chain reaction (PCR)-based methods. Of the stool samples assessed, 277 (48.3%) were positive for intestinal parasites and/or commensal protozoa. Centrifugal flotation presented the highest diagnostic sensitivity for Giardia infections. The kappa index revealed that both coproparasitological techniques closely agreed on the Giardia diagnosis (86%) versus satisfactory (72%) and poor (35%) concordances for commensal protozoan and helminth infections, respectively. Concerning Giardia molecular diagnosis, from the 71 microscopy-positive samples, specific amplification of gdh and tpi fragments was noted in 68 (95.7%) and 64 (90%) samples, respectively. Amplification of gdh and tpi genes was observed, respectively, in 95.7% and 90% of microscopy-positive Giardia samples. For 144 microscopy-negative samples, gdh and tpi gene amplification products were obtained from 8.3% and 35.9% samples, respectively. The agreement between these genes was about 40%. The centrifuge-flotation based method was the most suitable means of Giardia diagnosis assessed in the present study by combining accuracy and low cost.

Key words: Giardia duodenalis, children, diagnosis, PCR.

COPYRIGHT

© CEVAP 2011

SUBMISSION STATUS

Received: February 2, 2011.

Accepted: April 15, 2011.

Abstract published online: April 18, 2011.

Full paper published online: May 31, 2011.

CONFLICTS OF INTEREST

There is no conflict.

FINANCIAL SOURCE

The State of São Paulo Research Foundation (FAPESP) provided the financial grants (process number 06/56151-3).

ETHICS COMMITTEE APPROVAL

The present study was approved by the Research Ethics Committee of Botucatu Medical School, UNESP, under the protocol number 492/2009 CEPE.

CORRESPONDENCE TO

SEMÍRAMIS GUIMARÃES, Departamento de Parasitologia, Instituto de Biociências, UNESP, Botucatu, SP, 18618-000, Brasil. Phone: +55 14 3811-6239. Email: sgviana@ibb.unesp.br.