title: Serologic assessment of yellow fever immunity in the rural population of a yellow fever-endemic area in Central Brazil.
abstract: BACKGROUND
  The yellow fever epidemic that occurred in 1972/73 in Central Brazil surprised the majority of the population unprotected. A clinical-epidemiological survey conducted at that time in the rural area of 19 municipalities found that the highest (13.8%) number of disease cases were present in the municipality of Luziânia, State of Goiás.
  
  
  METHODS
  Thirty-eight years later, a new seroepidemiological survey was conducted with the aim of assessing the degree of immune protection of the rural population of Luziânia, following the continuous attempts of public health services to obtain vaccination coverage in the region. A total of 383 volunteers, aged between 5 and 89 years and with predominant rural labor activities (75.5%), were interviewed. The presence of antibodies against the yellow fever was also investigated in these individuals, by using plaque reduction neutralization test, and correlated to information regarding residency, occupation, epidemiological data and immunity against the yellow fever virus.
  
  
  RESULTS
  We found a high (97.6%) frequency of protective titers (>1:10) of neutralizing antibodies against the yellow fever virus; the frequency of titers of 1:640 or higher was 23.2%, indicating wide immune protection against the disease in the study population. The presence of protective immunity was correlated to increasing age.
  
  
  CONCLUSIONS
  This study reinforces the importance of surveys to address the immune state of a population at risk for yellow fever infection and to the surveillance of actions to control the disease in endemic areas.
authors.affiliation: Núcleo de Medicina Tropical, Universidade de Brasília, Brasília, DF, Brasil. vanessawolff@yahoo.com.br
authors.forename: Vanessa Wolff
authors.initials: VW
authors.lastname: Machado
authors.forename: Pedro Fernando da Costa
authors.initials: PF
authors.lastname: Vasconcelos
authors.forename: Eliana Vieira Pinto
authors.initials: EV
authors.lastname: Silva
authors.forename: João Barberino
authors.initials: JB
authors.lastname: Santos
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057134:Antibodies, Neutralizing / Q000097:blood*; D000914:Antibodies, Viral / Q000097:blood* / Q000276:immunology; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D019353:Endemic Diseases; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012424:Rural Population; D016036:Seroepidemiologic Studies; D015004:Yellow Fever / Q000453:epidemiology / Q000276:immunology*; D022341:Yellow Fever Vaccine / Q000008:administration & dosage* / Q000276:immunology; D015005:Yellow fever virus / Q000276:immunology*; D055815:Young Adult
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D022341:Yellow Fever Vaccine