title: Reduced risk of disease during postsecondary dengue virus infections.
abstract: BACKGROUND
  Antibodies induced by infection with any 1 of 4 dengue virus (DENV) serotypes (DENV-1-4) may influence the clinical outcome of subsequent heterologous infections. To quantify potential cross-protective effects, we estimated disease risk as a function of DENV infection, using data from longitudinal studies performed from September 2006 through February 2011 in Iquitos, Peru, during periods of DENV-3 and DENV-4 transmission.
  
  
  METHODS
  DENV infections before and during the study period were determined by analysis of serial serum samples with virus neutralization tests. Third and fourth infections were classified as postsecondary infections. Dengue fever cases were detected by door-to-door surveillance for acute febrile illness.
  
  
  RESULTS
  Among susceptible participants, 39% (420/1077) and 53% (1595/2997) seroconverted to DENV-3 and DENV-4, respectively. Disease was detected in 7% of DENV-3 infections and 10% of DENV-4 infections. Disease during postsecondary infections was reduced by 93% for DENV-3 and 64% for DENV-4, compared with primary and secondary infections. Despite lower disease rates, postsecondary infections constituted a significant proportion of apparent infections (14% [for DENV-3 infections], 45% [for DENV-4 infections]).
  
  
  CONCLUSIONS
  Preexisting heterotypic antibodies markedly reduced but did not eliminate the risk of disease in this study population. These results improve understanding of how preinfection history can be associated with dengue outcomes and DENV transmission dynamics.
authors.affiliation: Department of Entomology, University of California, Davis 95616, USA. smolkowski@ucdavis.edu
authors.forename: Sandra
authors.initials: S
authors.lastname: Olkowski
authors.forename: Brett M
authors.initials: BM
authors.lastname: Forshey
authors.forename: Amy C
authors.initials: AC
authors.lastname: Morrison
authors.forename: Claudio
authors.initials: C
authors.lastname: Rocha
authors.forename: Stalin
authors.initials: S
authors.lastname: Vilcarromero
authors.forename: Eric S
authors.initials: ES
authors.lastname: Halsey
authors.forename: Tadeusz J
authors.initials: TJ
authors.lastname: Kochel
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Scott
authors.forename: Steven T
authors.initials: ST
authors.lastname: Stoddard
mesh_terms: D057134:Antibodies, Neutralizing / Q000097:blood / Q000276:immunology; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D060085:Coinfection / Q000517:prevention & control* / Q000821:virology*; D056738:Cross Protection; D003715:Dengue / Q000453:epidemiology / Q000276:immunology* / Q000821:virology; D003716:Dengue Virus / Q000145:classification*; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D009500:Neutralization Tests; D010568:Peru / Q000453:epidemiology; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012703:Serotyping
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral
keywords: antibody cross-protection; dengue; dengue fever; seroepidemiology