title: Asymptomatic infections in blood donors harbouring Plasmodium: an invisible risk detected by molecular and serological tools.
abstract: Transfusion-transmitted malaria due to asymptomatic Plasmodium infections is a challenge for blood banks. There is a lack of data on the prevalence of asymptomatic infected blood donors and the incidence of transfusion-transmitted malaria in low endemicity areas worldwide. We estimated the frequency of blood donors harbouring Plasmodium in an area in which asymptomatic infections have been reported.
  
  
  
  To estimate the frequency of blood donors harbouring Plasmodium we used microscopy and molecular tools. Serological tests were applied to measure the exposure of candidates to Plasmodium antigens. Venous blood was collected from 91 candidates attending the "Pró-Sangue" Blood Centre Foundation in São Paulo, who lived in the municipality of Juquitiba, São Paulo, Brazil, where sporadic autochthonous cases of malaria have been described. Blood samples were used for parasitological, molecular and serological studies.
  
  
  
  Among the 91 samples examined, rare Plasmodium forms were observed in two donors. Genus real-time polymerase chain reaction analysis demonstrated Plasmodium amplification in three candidates and species-specific nested polymerase chain reaction identified P. malariae in two. ELISA-IgG was reactive in 42.9% of samples for P. vivax (Pv-MSP119) and in 6.6% for P. falciparum (Pf-Zw). ELISA-IgM was reactive in 2.2% of samples for P. vivax and in 4.4% for P. falciparum. An indirect immunofluorescence assay was reactive for P. malariae in 15.4% of cases.
  
  
  
  Reservoirs of Plasmodium represent a challenge for blood banks, since studies have shown that high levels of submicroscopic infections can occur in low transmission areas. The risk of transfusion-transmitted malaria presented here points to the need to conduct molecular investigations of candidate donors with any positive malarial antibody test.
authors.affiliation: Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Giselle F M C
authors.initials: GFMC
authors.lastname: Lima
authors.affiliation: Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Arroyo Sanchez
authors.affiliation: "Pró-Sangue" Blood Centre Foundation, São Paulo, Brazil.
authors.forename: José E
authors.initials: JE
authors.lastname: Levi
authors.affiliation: Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Mahyumi
authors.initials: M
authors.lastname: Fujimori
authors.affiliation: Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Luiza
authors.initials: L
authors.lastname: Da Cruz Caramelo
authors.affiliation: Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Arianni Rondelli
authors.initials: AR
authors.lastname: Sanchez
authors.affiliation: Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Ramos-Sanchez
authors.affiliation: Faculty of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Inoue
authors.affiliation: Epidemic Disease Control Unit, São Paulo, Brazil.
authors.forename: Maria
authors.initials: M
authors.lastname: De Jesus Costa-Nascimento
authors.affiliation: "Pró-Sangue" Blood Centre Foundation, São Paulo, Brazil.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Mendrone Junior
authors.affiliation: Faculty of Medicine, University of São Paulo, São Paulo, Brazil.|Epidemic Disease Control Unit, São Paulo, Brazil.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Di Santi
mesh_terms: D000953:Antigens, Protozoan / Q000097:blood*; D001782:Blood Donors; D046148:Donor Selection / Q000379:methods*; D005260:Female; D006801:Humans; D008288:Malaria / Q000097:blood* / Q000635:transmission; D008297:Male; D010961:Plasmodium
chemical_list: D000953:Antigens, Protozoan