title: Cross sectional study reveals a high percentage of asymptomatic Plasmodium vivax infection in the Amazon Rio Negro area, Brazil.
abstract: A parasitological, clinical, serological and molecular cross-sectional study carried out in a highly endemic malaria area of Rio Negro in the Amazon State, Brazil, revealed a high prevalence of asymptomatic Plasmodium vivax infection. A total of 109 persons from 25 families were studied in five villages. Ninety-nine inhabitants (90.8%) had at least one previous episode of malaria. Serology showed 85.7% and 46.9% of positivity when P. falciparum antigens and P. vivax MSP-1, respectively, were used. Twenty blood samples were PCR positive for P. vivax (20.4%) and no P. falciparum infection was evidenced by this technique. No individual presenting positive PCR reaction had clinical malaria during the survey neither in the six months before nor after, confirming that they were cases of asymptomatic infection. Only one 12 year old girl presented a positive thick blood smear for P. vivax. This is the first description of asymptomatic Plasmodium infection in this area studied.
authors.affiliation: Laboratório de Doenças Parasitarias, Departamento de Medicina Tropical, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brasil. marmutis@ioc.fiocruz.br
authors.forename: Martha C
authors.initials: MC
authors.lastname: Suárez-Mutis
authors.forename: Patricia
authors.initials: P
authors.lastname: Cuervo
authors.forename: Fabiana M S
authors.initials: FM
authors.lastname: Leoratti
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Moraes-Avila
authors.forename: Antonio Walter
authors.initials: AW
authors.lastname: Ferreira
authors.forename: Octavio
authors.initials: O
authors.lastname: Fernandes
authors.forename: José Rodrigues
authors.initials: JR
authors.lastname: Coura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D016054:DNA, Protozoan / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016780:Malaria, Vivax / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010966:Plasmodium vivax / Q000235:genetics / Q000276:immunology; D016133:Polymerase Chain Reaction; D015995:Prevalence
chemical_list: D000913:Antibodies, Protozoan; D016054:DNA, Protozoan