Serologic assessment of yellow fever immunity in the rural population of a yellow fever-endemic area in Central Brazil

• Published in: Revista da Sociedade Brasileira de Medicina Tropical Vol. 46; no. 2; pp. 166 - 171
• Main Authors: Machado, Vanessa Wolff, Vasconcelos, Pedro Fernando da Costa, Silva, Eliana Vieira Pinto, Santos, João Barberino
• Format: Journal Article
• Language: English
• Published: Brazil Sociedade Brasileira de Medicina Tropical 01-03-2013; Sociedade Brasileira de Medicina Tropical - SBMT; Sociedade Brasileira de Medicina Tropical (SBMT)
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Antibodies, Neutralizing - blood; Antibodies, Viral - blood; Antibodies, Viral - immunology; Brazil - epidemiology; Child; Child, Preschool; Endemic Diseases; Female; Goiás; Humans; Immunology; Luziânia; Male; Middle Aged; Population Surveillance; Rural areas; Rural Population; Seroepidemiologic Studies; TROPICAL MEDICINE; Vaccine protection; Vaccines; Viral infections; Yellow fever; Yellow Fever - epidemiology; Yellow Fever - immunology; Yellow Fever Vaccine - administration & dosage; Yellow Fever Vaccine - immunology; Yellow fever virus - immunology; Young Adult; Brazil; Vaccine protection; Luziânia; Yellow fever; Goiás
• ISSN: 0037-8682; 1678-9849; 1678-9849; 0037-8682
• DOI: 10.1590/0037-8682-0007-2012

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.
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.
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.
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.