A genus- and species-specific nested polymerase chain reaction malaria detection assay for epidemiologic studies

A nested polymerase chain reaction (PCR) assay that uses Plasmodium genus-s pecific primers for the initial PCR (nest 1) amplification and either genus - or species-specific primers for the nest 2 amplifications was tested on l aboratory and field samples. With in vitro cultured Plasmodium falciparum-i nfected blood samples, it was capable of detecting six parasites/mu l of bl ood using DNA prepared from 25-mu l blood spots on filter paper The assay w as evaluated on fingerprick blood samples collected on filter paper from 12 9 individuals living in a malaria-endemic area in Malaysia. Malaria prevale nce by genus-specific nested PCR was 35.6% (46 of 129) compared with 28.7% (37 of 129) by microscopy. The nested PCR detected seven more malaria sampl es than microscopy in the first round of microscopic examination, malaria i n three microscopically negative samples, six double infections identified as single infections by microscopy and one triple infection identified as a double infection by microscopy. The nested PCR assay described is a sensit ive technique for collecting accurate malaria epidemiologic data. When coup led with simple blood spot sampling, it is particularly useful for screenin g communities in remote regions of the world.