title: Incomplete Protection against Dengue Virus Type 2 Re-infection in Peru.
abstract: BACKGROUND
  Nearly half of the world's population is at risk for dengue, yet no licensed vaccine or anti-viral drug is currently available. Dengue is caused by any of four dengue virus serotypes (DENV-1 through DENV-4), and infection by a DENV serotype is assumed to provide life-long protection against re-infection by that serotype. We investigated the validity of this fundamental assumption during a large dengue epidemic caused by DENV-2 in Iquitos, Peru, in 2010-2011, 15 years after the first outbreak of DENV-2 in the region.
  
  
  RESULTS
  We estimated the age-dependent prevalence of serotype-specific DENV antibodies from longitudinal cohort studies conducted between 1993 and 2010. During the 2010-2011 epidemic, active dengue cases were identified through active community- and clinic-based febrile surveillance studies, and acute inapparent DENV infections were identified through contact tracing studies. Based on the age-specific prevalence of DENV-2 neutralizing antibodies, the age distribution of DENV-2 cases was markedly older than expected. Homologous protection was estimated at 35.1% (95% confidence interval: 0%-65.2%). At the individual level, pre-existing DENV-2 antibodies were associated with an incomplete reduction in the frequency of symptoms. Among dengue cases, 43% (26/66) exhibited elevated DENV-2 neutralizing antibody titers for years prior to infection, compared with 76% (13/17) of inapparent infections (age-adjusted odds ratio: 4.2; 95% confidence interval: 1.1-17.7).
  
  
  CONCLUSIONS
  Our data indicate that protection from homologous DENV re-infection may be incomplete in some circumstances, which provides context for the limited vaccine efficacy against DENV-2 in recent trials. Further studies are warranted to confirm this phenomenon and to evaluate the potential role of incomplete homologous protection in DENV transmission dynamics.
authors: U.S. Naval Medical Research Unit No. 6, Lima and Iquitos, Perú
authors: Brett M
authors: BM
authors: Forshey
authors: Indiana University School of Public Health, Bloomington, Indiana, United States of America.|Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.
authors: Robert C
authors: RC
authors: Reiner
authors: Department of Entomology and Nematology, University of California, Davis, Davis, California, United States of America.
authors: Sandra
authors: S
authors: Olkowski
authors: U.S. Naval Medical Research Unit No. 6, Lima and Iquitos, Perú|Department of Entomology and Nematology, University of California, Davis, Davis, California, United States of America.
authors: Amy C
authors: AC
authors: Morrison
authors: U.S. Naval Medical Research Unit No. 6, Lima and Iquitos, Perú
authors: Angelica
authors: A
authors: Espinoza
authors: Department of Entomology and Nematology, University of California, Davis, Davis, California, United States of America.|Department of Biology, Andrews University, Berrien Springs, Michigan, United States of America.
authors: Kanya C
authors: KC
authors: Long
authors: U.S. Naval Medical Research Unit No. 6, Lima and Iquitos, Perú
authors: Stalin
authors: S
authors: Vilcarromero
authors: Universidad Nacional de la Amazonía Peruana, Iquitos, Perú|Dirección Regional de Salud Loreto, Iquitos, Perú
authors: Wilma
authors: W
authors: Casanova
authors: University of New Mexico, Albuquerque, Albuquerque, New Mexico, United States of America.
authors: Helen J
authors: HJ
authors: Wearing
authors: U.S. Naval Medical Research Unit No. 6, Lima and Iquitos, Perú
authors: Eric S
authors: ES
authors: Halsey
authors: U.S. Naval Medical Research Unit No. 6, Lima and Iquitos, Perú
authors: Tadeusz J
authors: TJ
authors: Kochel
authors: Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.|Department of Entomology and Nematology, University of California, Davis, Davis, California, United States of America.
authors: Thomas W
authors: TW
authors: Scott
authors: Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.|Department of Entomology and Nematology, University of California, Davis, Davis, California, United States of America.
authors: Steven T
authors: ST
authors: Stoddard
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000453:epidemiology* / Q000517:prevention & control*; D003716:Dengue Virus / Q000276:immunology*; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012008:Recurrence; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral