Vasconcelos P F, Rodrigues S G, Degallier N, Moraes M A, da Rosa J F, da Rosa E S, Mondet B, Barros V L, da Rosa A P
World Health Organization Reference Centre for Arboviruses/Servico de Arbovirus e Servico de Patologia, Instituto Evandro Chagas/FNS-MS, Belem, Para, Brazil.
Am J Trop Med Hyg. 1997 Aug;57(2):132-7. doi: 10.4269/ajtmh.1997.57.132.
Yellow fever virus transmission was very active in Maranhao State in Brazil in 1993 and 1994. An investigation was carried out to evaluate the magnitude of the epidemic. In 1993, a total of 932 people was examined for yellow fever from Maranhao: 70 were positive serologically, histopathologically, and/or by virus isolation, and another four cases were diagnosed clinically and epidemiologically. In Mirador (17,565 inhabitants), the incidence was 3.5 per 1,000 people (case fatality rate [number of deaths/number of cases diagnosed] = 16.4%), while in a rural yellow fever risk area (14,659 inhabitants), the incidence was 4.2 and the case-fatality rate was 16.1% (10 of 62). A total of 45.2% (28 of 62) asymptomatic infections were registered. In 1994, 49 serum samples were obtained and 16 cases were confirmed (two by virus isolation, two by seroconversion, and 12 by serology). No fatal cases were reported. In 1993, 936 potential yellow fever vectors were captured in Mirador and a single strain was isolated from a pool of Haemagogus janthinomys (infection rate = 0.16%). In 1994, 16 strains were isolated from 1,318 Hg. janthinomys (infection rate = 1.34%) and one Sabethes chloropterus (infection rate = 1.67%). Our results suggest that this was the most extensive outbreak of yellow fever in the last 20 years in Brazil. It is also clear that the lack of vaccination was the principal reason for the epidemic, which occurred between April and June, during the rainy season, a period in which the mosquito population in the forest increases.
1993年和1994年，黄热病病毒在巴西马拉尼昂州的传播极为活跃。为此开展了一项调查，以评估疫情的规模。1993年，马拉尼昂州共有932人接受了黄热病检查：70人血清学、组织病理学和/或病毒分离检测呈阳性，另有4例经临床和流行病学诊断确诊。在米拉多尔（有17,565名居民），发病率为每1000人中有3.5例（病死率[死亡人数/确诊病例数]=16.4%），而在一个农村黄热病风险地区（有14,659名居民），发病率为4.2例，病死率为16.1%（62例中有10例死亡）。共记录到45.2%（62例中的28例）无症状感染病例。1994年，采集了49份血清样本，确诊16例（2例通过病毒分离确诊，2例通过血清转化确诊，12例通过血清学确诊）。未报告死亡病例。1993年，在米拉多尔捕获了936只潜在的黄热病传播媒介，从一组黄带血蝇中分离出一个毒株（感染率=0.16%）。1994年，从1318只黄带血蝇中分离出16个毒株（感染率=1.34%），从一只绿翅骚蚊中分离出一个毒株（感染率=1.67%）。我们的研究结果表明，这是巴西过去20年中最广泛的黄热病疫情。同样明显的是，缺乏疫苗接种是此次疫情的主要原因，疫情发生在4月至6月的雨季，这一时期森林中的蚊虫数量会增加。
