Demographic profile of sylvatic yellow fever in Brazil from 1973 to 2008

• Published in: Transactions of the Royal Society of Tropical Medicine and Hygiene Vol. 107; no. 5; pp. 324 - 327
• Main Authors: Câmara, Fernando Portela, de Carvalho, Luiz Max, Gomes, Ana Luisa Bacellar
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-05-2013
• Subjects: Acute Disease; Adolescent; Adult; Arboviroses; Biological and medical sciences; Brazil - epidemiology; Demography; Female; General aspects; Human viral diseases; Humans; Infectious diseases; Male; Medical sciences; Periodicity; Risk Factors; Tropical viral diseases; Viral diseases; Yellow fever; Yellow Fever - epidemiology; Yellow Fever - mortality; Yellow Fever - prevention & control; Yellow Fever - transmission; Yellow Fever Vaccine; Young Adult; South America; Brazil; America; Sylvatic yellow fever; Brazil; Yellow fever vaccine; Demographic profile; Infection; Prevention; Immunoprophylaxis; Viral disease; Arbovirus disease; Tropical medicine; Vaccine; Yellow fever
• ISSN: 0035-9203; 1878-3503
• DOI: 10.1093/trstmh/trt014

Background
Yellow fever is an acute, frequently fatal, febrile arbovirosis that in Brazil occurs only in the sylvatic form. Sylvatic yellow fever (SYF) appears in sporadic outbreaks over a large area of Brazil. In this paper, we analyze the demographic profile of 831 SYF cases that occurred between 1973 and 2008, to determine which segments of the exposed population are at greater risk.
Methods
Data were statistically analyzed and were also geo-referenced in order to observe their spatial pattern. The basic reproductive number of infections, R0, was estimated by the ratio between average life expectancy and the average age of the cases.
Results
SYF cases showed a modal profile of young male adults, approximately 30 years of age, living in rural areas of the states of Pará, Goiás, Maranhão and Minas Gerais, who were unvaccinated or whose vaccination was out of date. The disease showed a high mortality rate (51%, 421/831) among the notified cases, with death occurring on around the seventh day of illness for most patients. The R0 for SYF was estimated at approximately 2.4.
Conclusion
The results of this study suggest that lack of vaccination coverage is a major risk factor for SYF, and that the groups most at risk are migrant laborers, farm workers and tourists.