Scherer W F, Ordonez J V, Dickerman R W, Navarro J E
Am J Epidemiol. 1976 Jul;104(1):60-73. doi: 10.1093/oxfordjournals.aje.a112274.
Evidence was sought during 1970-1975 of persistence of equine-virulent Venezuelan encephalitis (VE) virus in regions of Central America that were heavily involved in the epidemic-equine epizootic of 1969. (a) Four sentinel horses were exposed in an arid, upland region of the Atlantic drainage of Guatemala during August-October 1970, but no horse became infected. (b) The epicenter region of the 1969 outbreak, in southwestern Guatemala and southwestern El Salvador, was studied during July 1970-February 1974; no antibody developed in sentinel horses, sentinel hamsters did not die, mosquitoes yielded no virus, wild rats had no detectable VE virus HI antibody. Unexplained decreases in populations of wild terrestrial mammals possibly limited maintenance of VE virus. However, mosquitoes were plentiful and present in the same species composition found at a focus of enzootic VE virus about 35 km northwest of the epicenter region. (c) In studies at two Guatemalan ranches near the epicenter, where horses died in 1969, VE viruse infected sentinel horses along one of three lakes on one ranch during the wet season of 1972 but not during the dry or wet seasons of 1973; the titers of neutralizing antibodies in these four horses were higher against an enzootic strain of VE virus than against an epizootic strain. During 1970 and 1971, VE virus was isolated from sentinel hamsters exposed at a marsh on the other ranch, but Vero plaque characteristics were those of enzootic VE virus. (d) The only epizootic activity of VE virus discovered in Central America in 1970-1975 occurred in Nicaragua between April and June 1972. Several hundred horses died, and N antibody, like that engendered by epizootic virus, was found in two young, unvaccinated horses. Whether this represented persistence of epizootic VE virus or reintroduction of virus is unknown.
1970年至1975年期间，在1969年马流行性委内瑞拉脑炎（VE）疫情严重的中美洲地区，寻找马烈性委内瑞拉脑炎病毒持续存在的证据。（a）1970年8月至10月，在危地马拉大西洋流域的一个干旱高地地区，让4匹哨兵马暴露，但没有马被感染。（b）1970年7月至1974年2月，对1969年疫情的震中地区，即危地马拉西南部和萨尔瓦多西南部进行了研究；哨兵马未产生抗体，哨兵仓鼠未死亡，蚊子未分离到病毒，野生大鼠未检测到VE病毒血凝抑制抗体。野生陆生哺乳动物数量不明原因的减少可能限制了VE病毒的维持。然而，蚊子数量众多，且种类组成与震中地区西北约35公里处的地方性VE病毒疫源地相同。（c）在震中附近的两个危地马拉牧场进行的研究中，1969年有马死亡，1972年雨季期间，VE病毒在其中一个牧场的三个湖泊之一沿岸感染了哨兵马，但在1973年的旱季或雨季均未感染；这4匹马中针对地方性VE病毒株的中和抗体滴度高于针对流行性病毒株的中和抗体滴度。1970年和1971年，从另一个牧场沼泽地暴露的哨兵仓鼠中分离到VE病毒，但非洲绿猴肾细胞空斑特征为地方性VE病毒的特征。（d）1970年至1975年在中美洲发现的VE病毒唯一的流行活动发生在1972年4月至6月的尼加拉瓜。数百匹马死亡，在两匹未接种疫苗的年轻马中发现了与流行性病毒产生的抗体类似的抗体。这是代表流行性VE病毒的持续存在还是病毒的重新引入尚不清楚。
