title: Plasmodium malariae in the Colombian Amazon region: you don't diagnose what you don't suspect.
abstract: BACKGROUND
  Malaria is a worldwide public health problem; parasites from the genus Plasmodium spp. are the aetiological agent of this disease. The parasite is mainly diagnosed by microscope-based techniques. However, these have limited sensitivity. Many asymptomatic infections are sub-microscopic and can only be detected by molecular methods. This study was aimed at comparing nested PCR results to those obtained by microscope for diagnosing malaria and to present epidemiological data regarding malaria in Colombia's Amazon department.
  
  
  METHODS
  A total of 1392 blood samples (taken by venepuncture) from symptomatic patients in Colombia's Amazon department were analysed in parallel by thick blood smear (TBS) test and nested PCR for determining Plasmodium spp. infection and identifying infecting species, such as Plasmodium vivax, Plasmodium malariae and/or Plasmodium falciparum. Descriptive statistics were used for comparing the results from both tests regarding detection of the disease, typing infecting species and their prevalence in the study region. Bearing the microscope assay in mind as gold standard, PCR diagnosis performance was evaluated by statistical indicators.
  
  
  CONCLUSIONS
  The present study revealed great differences between both diagnostic tests, as well as suggesting high P. malariae prevalence from a molecular perspective. This differed profoundly from previous studies in this region of Colombia, usually based on the TBS test, suggesting that diagnosis by conventional techniques could lead to underestimating the prevalence of certain Plasmodium spp. having high circulation in this area. The present results highlight the need for modifying state malaria surveillance schemes for more efficient strategies regarding the detection of this disease in endemic areas. The importance of PCR as a back-up test in cases of low parasitaemia or mixed infection is also highlighted.
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.
authors.forename: Carlos Hernando
authors.initials: CH
authors.lastname: Niño
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.
authors.forename: Juan Ricardo
authors.initials: JR
authors.lastname: Cubides
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.
authors.forename: Paola Andrea
authors.initials: PA
authors.lastname: Camargo-Ayala
authors.affiliation: Gobernación del Amazonas, Calle 10 # 10-77, Leticia, Colombia.
authors.forename: Carlos Arturo
authors.initials: CA
authors.lastname: Rodríguez-Celis
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.
authors.forename: Teódulo
authors.initials: T
authors.lastname: Quiñones
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.
authors.forename: Moisés Tomás
authors.initials: MT
authors.lastname: Cortés-Castillo
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.
authors.forename: Lizeth
authors.initials: L
authors.lastname: Sánchez-Suárez
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.|School of Medicine, Universidad Nacional de Colombia, Avenida Carrera 30 # 45, Bogotá, Colombia.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Sánchez
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia.|School of Medicine, Universidad Nacional de Colombia, Avenida Carrera 30 # 45, Bogotá, Colombia.
authors.forename: Manuel Elkin
authors.initials: ME
authors.lastname: Patarroyo
authors.affiliation: Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50 # 26-20, Bogotá, Colombia. mapatarr.fidic@gmail.com.|School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24#63C-69, Bogotá, Colombia. mapatarr.fidic@gmail.com.
authors.forename: Manuel Alfonso
authors.initials: MA
authors.lastname: Patarroyo
mesh_terms: D003105:Colombia / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003955:Diagnostic Tests, Routine / Q000379:methods*; D006801:Humans; D008288:Malaria / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology*; D008853:Microscopy / Q000379:methods*; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D010963:Plasmodium falciparum / Q000302:isolation & purification; D010965:Plasmodium malariae / Q000302:isolation & purification*; D010966:Plasmodium vivax / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods*; D015995:Prevalence
keywords: Colombian Amazon region; Malaria; Microscopy; Nested PCR; Thick blood smear