title: Detection of Plasmodium falciparum and Plasmodium vivax subclinical infection in non-endemic region: implications for blood transfusion and malaria epidemiology.
abstract: BACKGROUND
  In Brazil, malaria is endemic in the Amazon River basin and non-endemic in the extra-Amazon region, which includes areas of São Paulo state. In this state, a number of autochthonous cases of malaria occur annually, and the prevalence of subclinical infection is unknown. Asymptomatic infections may remain undetected, maintaining transmission of the pathogen, including by blood transfusion. In these report it has been described subclinical Plasmodium infection in blood donors from a blood transfusion centre in São Paulo, Brazil.
  
  
  METHODS
  In this cross-sectional study, representative samples of blood were obtained from 1,108 healthy blood donors at the Fundação Pró-Sangue Hemocentro de São Paulo, the main blood transfusion centre in São Paulo. Malaria exposure was defined by the home region (exposed: forest region; non-exposed: non-forest region). Real-time PCR was used to detect Plasmodium falciparum and Plasmodium vivax. Subclinical malaria cases were geo-referenced.
  
  
  RESULTS
  Eighty-four (7.41%) blood donors tested positive for Plasmodium; 57 of these were infected by P. falciparum, 25 by P. vivax, and 2 by both. The prevalence of P. falciparum and P. vivax was 5.14 and 2.26, respectively. The overall prevalence ratio (PR) was 3.23 (95% confidence interval (CI) 2.03, 5.13); P. falciparum PR was 16.11 (95% CI 5.87, 44.21) and P. vivax PR was 0.47 (95% CI 0.2, 1.12). Plasmodium falciparum subclinical malaria infection in the Atlantic Forest domain was present in the mountain regions while P. vivax infection was observed in cities from forest-surrounded areas.
  
  
  CONCLUSIONS
  The presence of Plasmodium in healthy blood donors from a region known as non-endemic, which is important in the context of transfusion biosafety, was described. Infected recipients may become asymptomatic carriers and a reservoir for parasites, maintaining their transmission. Furthermore, P. falciparum PR was positively associated with the forest environment, and P. vivax was associated with forest fragmentation.
authors.forename: Luciana M F
authors.initials: LM
authors.lastname: Maselli
authors.forename: Debora
authors.initials: D
authors.lastname: Levy
authors.forename: Gabriel Z
authors.initials: GZ
authors.lastname: Laporta
authors.forename: Aline M
authors.initials: AM
authors.lastname: Monteiro
authors.forename: Linah A
authors.initials: LA
authors.lastname: Fukuya
authors.forename: Maria F
authors.initials: MF
authors.lastname: Ferreira-da-Cruz
authors.forename: Claudio T
authors.initials: CT
authors.lastname: Daniel-Ribeiro
authors.forename: Pedro E
authors.initials: PE
authors.lastname: Dorlhiac-Llacer
authors.forename: Maria Anice M
authors.initials: MA
authors.lastname: Sallum
authors.affiliation: Laboratory of Genetics and Molecular Hematology (LIM31), University of Sao Paulo School of Medicine, Av, Dr, Enéas de Carvalho Aguiar, 155 - 1st floor - room 43, São Paulo, SP 05403-000, Brazil. spbydlow@usp.br.
authors.forename: Sérgio P
authors.initials: SP
authors.lastname: Bydlowski
mesh_terms: D058345:Asymptomatic Infections / Q000453:epidemiology*; D001782:Blood Donors; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology / Q000635:transmission; D016780:Malaria, Vivax / Q000175:diagnosis* / Q000453:epidemiology / Q000635:transmission; D010963:Plasmodium falciparum / Q000235:genetics / Q000302:isolation & purification*; D010966:Plasmodium vivax / Q000235:genetics / Q000302:isolation & purification*; D060888:Real-Time Polymerase Chain Reaction; D065227:Transfusion Reaction