Bowen G S, Calisher C H
J Clin Microbiol. 1976 Jul;4(1):22-7. doi: 10.1128/jcm.4.1.22-27.1976.
During the 1971 epidemic of Venezuelan equine encephalomyelitis (VEE) in south Texas, 203 suspect VEE cases were evaluated by the Center for Disease Control. Sixty-seven were confirmed as cases of VEE. Laboratory confirmation was accomplished by isolation of VEE virus from a serum specimen taken during the acute illness in 50 (75%) of the confirmed cases. Serological confirmation was obtained in 17 cases (25%). Virus isolations were most often obtained from sera collected during the first 3 days of illness. Peak serum virus titers (algebraic mean, 10(5-7) suckling mouse intracranial 50% lethal doses [SMICLD50] per ml) occurred on day 2 of illness. One-half of the sera from which virus was isolated contained at least 10(5) SMICLD50/ml, which has been shown to be sufficient to infect some vector mosquitoes. Blood from 13 virus-positive VEE cases was obtained 1 and 11 months after illness. Hemagglutination-inhibiting, complement-fixing, and neutralizing antibodies were formed by all 13 patients 1 month after illness. Hemagglutination-inhibiting antibody titers were essentially unchanged 11 months after illness. Complement-fixing antibody was undetectable 11 months after illness in 23% of cases and was detectable at dilutions of 1:8 or 1:6 in 77%. Neutralizing antibody (measured by log neutralization index) was not detectable 1 year after illness in one person (8%); titers had declined from 1.0 to 2.0 in 46%, were unchanged in 39%, and were not tested in one person (8%). No evidence of intrafamilial spread of VEE virus was obtained in either of two illness and antibody surveys. A randomized household illness and antibody survey of 681 Port Isabel residents revealed an inapparent infection ratio of 1:11 and an overall antibody prevalence of 3.2%.
1971年得克萨斯州南部发生委内瑞拉马脑炎（VEE）疫情期间，疾病控制中心对203例疑似VEE病例进行了评估。其中67例被确认为VEE病例。实验室确诊是通过从50例（75%）确诊病例急性发病期采集的血清标本中分离出VEE病毒来完成的。17例（25%）通过血清学确诊。病毒分离最常从发病头3天采集的血清中获得。血清病毒滴度峰值（代数平均值，每毫升10(5 - 7) 乳鼠脑内半数致死剂量 [SMICLD50]）出现在发病第2天。分离出病毒的血清中，一半含有至少10(5) SMICLD50/ml，这已被证明足以感染一些病媒蚊子。13例病毒阳性的VEE病例在发病后1个月和11个月采集了血液。所有13例患者在发病1个月后均形成了血凝抑制、补体结合和中和抗体。发病11个月后，血凝抑制抗体滴度基本未变。发病11个月后，23%的病例补体结合抗体检测不到，77%的病例在1:8或1:6稀释度时可检测到。1年后，1人（8%）检测不到中和抗体（以对数中和指数衡量）；46%的人中和抗体滴度从1.0降至2.0，39%的人中和抗体滴度未变，1人（8%）未检测。在两项发病和抗体调查中，均未发现VEE病毒家庭内传播的证据。对681名伊莎贝尔港居民进行的随机家庭发病和抗体调查显示，隐性感染率为1:11，总体抗体阳性率为3.2%。
