title: Sensitivity of nested-PCR for plasmodium detection in pooled whole blood samples and its usefulness to blood donor screening in endemic areas.
abstract: Transfusion-transmitted malaria is a severe disease with high fatality rate. Most Brazilian blood banks in the Amazon region perform malaria screening using microscopic examination (thick smears). Since low parasite concentrations are expected in asymptomatic blood donors a high sensitivity test should be used for donor screening. This study determined the sensitivity of a nested-PCR for plasmodium detection in pooled samples. We performed a one-stage criterion validation study with 21 positive samples pooled with samples from ten negative volunteer until three different concentrations were reached (0.33; 0.25; 0.20 parasites/μL - p/μL). Nested PCR was performed as described by Snounou et al. (1993). Sensitivities (and confidence intervals) were determined by stratum of final parasite concentration on the pooled samples. All samples with parasitemia values of 0.33 and 0.25 p/μL had 100% sensitivity (95%CI=86.3-100). One negative result was obtained from a sample with 0.20 p/μL sensitivity=95.2% (95%CI=76.2-99.9). Compared to parasitemia detectable under ideal conditions of thick smear, this nested-PCR in pooled sample was able to detect 40 times more parasites per microliter. Nested-PCR in pooled samples should be considered as a high sensitive alternative to thick smear for donor screening in blood banks at endemic regions. Local authorities need to assess cost:benefit advantages of this method compared to alternatives.
authors: Tropical Medicine Center, Universidade de Brasília, Brasília, DF, Brazil; National Agency for Health Surveillance (Anvisa), Brazil. Electronic address: danielcoradi@gmail.com.
authors: Daniel Roberto Coradi
authors: DR
authors: de Freitas
authors: Universidade Federal do Mato Grosso, Cuiabá, MT, Brazil.
authors: Luciano Teixeira
authors: LT
authors: Gomes
authors: Universidade Federal do Mato Grosso, Cuiabá, MT, Brazil.
authors: Cor Jesus F
authors: CJ
authors: Fontes
authors: Tropical Medicine Center, Universidade de Brasília, Brasília, DF, Brazil.
authors: Pedro Luiz
authors: PL
authors: Tauil
authors: Tropical Medicine Center, Universidade de Brasília, Brasília, DF, Brazil.
authors: Lorrin W
authors: LW
authors: Pang
authors: Tropical Medicine Center, Universidade de Brasília, Brasília, DF, Brazil.
authors: Elisabeth Carmen
authors: EC
authors: Duarte
mesh_terms: D001938:Brazil; D046148:Donor Selection / Q000379:methods*; D019353:Endemic Diseases; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood / Q000235:genetics; D016780:Malaria, Vivax / Q000097:blood / Q000235:genetics; D008297:Male; D010963:Plasmodium falciparum / Q000235:genetics*; D010966:Plasmodium vivax / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods*
keywords: Blood safety; Donor screening; Malaria; Nested PCR; Sensitivity