Real-time PCR versus conventional PCR for malaria parasite detection in low-grade parasitemia.
We have optimized a faster and cheaper real-time PCR and developed a conventional genus specific PCR based on 18S rRNA gene to detect malaria parasites in low-grade parasitemias. Additionally, we compared these PCRs to the OptiMAL-IT test. Since there is no consensus on choice of standard quantitative curve in real-time assays, we decided to investigate the performance of parasite DNA from three different sources: "genome", amplicon and plasmid. The amplicon curve showed the best efficiency in quantifying parasites. Both PCR assays detected 100% of the clinical samples tested; the sensitivity threshold was 0.5 parasite/mul and no PCR positive reaction occurred when malaria parasites were not present. Conversely, if OptiMAL-IT were employed for malaria diagnosis, 30% of false-negative results could be expected. We conclude that PCR assays have potential for detecting malaria parasites in asymptomatic infections, in evaluation of malaria vaccine molecule candidates, for screening blood donors, especially in endemic areas, or even in monitoring malaria therapy.
Gama
Bianca E
BE
Laboratory of Malaria Research, Department of Immunology, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, Brazil.
Silva-Pires
Felipe do E S
Fdo E
Lopes
Mauro N'Kruman R
MN
Cardoso
Maria Angélica B
MA
Britto
Constança
C
Torres
Kátia L
KL
de Mendonça Lima
Leila
L
de Souza
José Maria
JM
Daniel-Ribeiro
Cláudio T
CT
Ferreira-da-Cruz
Maria  de Fátima
M
D000818:Animals; D016054:DNA, Protozoan / Q000097:blood / Q000737:chemistry; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis*; D016780:Malaria, Vivax / Q000175:diagnosis*; D018512:Parasitemia / Q000175:diagnosis*; D010963:Plasmodium falciparum / Q000235:genetics / Q000302:isolation & purification*; D010966:Plasmodium vivax / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000592:standards; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012008:Recurrence; D012680:Sensitivity and Specificity
D016054:DNA, Protozoan; D012337:RNA, Ribosomal, 18S