Evaluation of a real-time polymerase chain reaction assay for the diagnosis of malaria in patients from Jazan area, Saudi Arabia

Abstract EN

A real-time PCR assay with conventional microscopy by Giemsa-stained blood films was used.

PCR was completed in an hour and ide-ntified the Plasmodium species in a single reaction.

Blood was collected, and DNA was extracted.

A genus-specific primer set corres-ponding to 18S ribosomal RNA was used to amplify target sequence.

Fluorescence resonance energy technology hybridization probes were designed for P.

falciparum over a region containing base pair mis-matches allowed Plasmodium species differentiation.

Microscopically positive patients (n = 60) were positive with real-time assay (100 % sensitivity).

58 were single-species infections caused by P.

falcipa-rum; mixed infections (P.

falciparum & P.

vivax) were shown by real-time assay.

Six out of 30 negative microscopy specimens were positive by real-time PCR (80 % specificity).

The discrepant results could be due to the subjective nature of microscopy and analytical objectivity of PCR, and high analytical sensitivity of real-time assay (1 parasite / μl) compared to microscopy (50 parasites / μl).

Six patients were retested with ICT malaria test and 4 were positive showing that PCR results were correct.

There was low correlation between parasi-temia by microscopy and gene copy number for P.

falciparum (r = 0.2 ; P =0.05 [Spearman]).