Sector for Infectious Diseases Epidemiology, Institute of Microbiology, Federal University of Rio de Janeiro, Health Sciences Center - Block I, University City - Fundão Island, Rio de Janeiro 21941-590, Brazil.
Trans R Soc Trop Med Hyg. 2013 May;107(5):324-7. doi: 10.1093/trstmh/trt014. Epub 2013 Feb 26.
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.
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.
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in rural areas of the states of Pará, Goiás, Maranhão and Minas Gerais, who were unvaccinated or whose vaccination was out of date.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.
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.
黄热病是一种急性、常致命的虫媒病毒性疾病，在巴西仅以丛林型出现。丛林型黄热病（SYF）在巴西的广大地区呈散发性爆发。本文分析了 1973 年至 2008 年间发生的 831 例 SYF 病例的人口统计学特征，以确定哪些暴露人群的风险更大。
对数据进行了统计分析，并进行了地理参考，以观察其空间模式。通过平均预期寿命与病例平均年龄的比值来估计感染的基本繁殖数，R0。
SYF 病例的典型特征为年轻男性成年人，年龄约为 30 岁，居住在帕拉、戈亚斯、马拉尼昂和米纳斯吉拉斯州的农村地区，他们未接种疫苗或疫苗已过期。该疾病的通报病例死亡率较高（51%，421/831），大多数患者在发病后的第 7 天左右死亡。SYF 的 R0 约为 2.4。
本研究结果表明，疫苗接种覆盖率不足是 SYF 的一个主要危险因素，风险最大的人群是流动工人、农场工人和游客。
