title: Evaluation of real-time PCR assay to detect Schistosoma mansoni infections in a low endemic setting.
abstract: BACKGROUND
  Schistosomiasis constitutes a major public health problem, and 200 million people are estimated to be infected with schistosomiasis worldwide. In Brazil, schistosomiasis has been reported in 19 states, showing areas of high and medium endemicity and a wide range of areas of low endemicity (ALE). Barra Mansa in Rio de Janeiro state has an estimated prevalence of 1%. ALE represent a new challenge for the helminth control because about 75% of infected individuals are asymptomatic and infections occur with a low parasite load (<100 eggs per gram of feces), causing a decrease in sensitivity of stool parasitological techniques, which are a reference for the laboratory diagnosis of this helminth. The objective of this study was to evaluate the performance of a TaqMan quantitative polymerase chain reaction (qPCR) technique in serum and feces DNA samples using the techniques of Kato-Katz (KK), Hoffman, Pons and Janer (HH) as references, during an epidemiological survey using fecal samples and sera from randomized residents from an ALE.
  
  
  METHODS
  A cross-sectional study conducted from April to December 2011 using a probabilistic sampling that collected 572 fecal and serum samples. The laboratory diagnostic techniques used were: KK, HH and qPCR (feces and serum).
  
  
  RESULTS
  We obtained the following results using the different diagnostic techniques: KK and HH, 0.9% (n =5); qPCR-feces, 9.6% (n =55); and qPCR-serum, 1.4% (n =8). The qPCR-feces presented the highest positivity, whereas the techniques of HH and KK were the least sensitive to detect infections (0.8%). Compared to HH and KK, qPCR-feces showed a statistically significant difference in positivity (p <0.05), although with poor agreement.
  
  
  CONCLUSIONS
  The positivity rate presented by the qPCR approach was far higher than that obtained by parasitological techniques. The lack of adequate surveillance in ALE of schistosomiasis indicates a high possibility of these areas being actually of medium and high endemicity. This study presents a control perspective, pointing to the possibility of using combined laboratory tools in the diagnosis of schistosomiasis in ALE.
authors.affiliation: Department of Infectious and Parasitic Diseases, School of Medicine of the University of São Paulo - LIM-06, São Paulo, SP, Brazil. cristinasanto@usp.br.
authors.forename: Maria Cristina Carvalho
authors.initials: MC
authors.lastname: Espírito-Santo
authors.forename: Mónica Viviana
authors.initials: MV
authors.lastname: Alvarado-Mora
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Dias-Neto
authors.forename: Lívia Souza
authors.initials: LS
authors.lastname: Botelho-Lima
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Moreira
authors.forename: Maria
authors.initials: M
authors.lastname: Amorim
authors.forename: Pedro Luiz Silva
authors.initials: PL
authors.lastname: Pinto
authors.forename: Ashley R
authors.initials: AR
authors.lastname: Heath
authors.forename: Vera Lúcia Pagliusi
authors.initials: VL
authors.lastname: Castilho
authors.forename: Elenice Messias do Nascimento
authors.initials: EM
authors.lastname: Gonçalves
authors.forename: Expedito José de Albuquerque
authors.initials: EJ
authors.lastname: Luna
authors.forename: Flair José
authors.initials: FJ
authors.lastname: Carrilho
authors.forename: João Renato Rebello
authors.initials: JR
authors.lastname: Pinho
authors.forename: Ronaldo Cesar Borges
authors.initials: RC
authors.lastname: Gryschek
mesh_terms: D000328:Adult; D000818:Animals; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D018509:DNA, Helminth / Q000097:blood / Q000235:genetics; D019353:Endemic Diseases; D005243:Feces / Q000469:parasitology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D059208:Parasite Load; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction; D012550:Schistosoma mansoni / Q000235:genetics*; D012555:Schistosomiasis mansoni / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D018509:DNA, Helminth