The University of Tennessee, Department of Entomology & Plant Pathology, Knoxville, TN 37996-4560, USA.
BMC Infect Dis. 2011 Jan 26;11:29. doi: 10.1186/1471-2334-11-29.
La Crosse virus (LACV) is a major cause of pediatric encephalitis in the United States. Since the mid-1980s, the number of reported cases of LACV infection in West Virginia has continued to rise and the state currently reports the most cases in the United States. The purpose of this study was to investigate and describe the spatial epidemiology and clinical presentation of LACV infection cases reported in West Virginia, as well as to provide a description of the environmental conditions present at the residences of the LACV infection cases.
Descriptive and spatial analyses were performed on LACV infection cases reported to the West Virginia Department of Health from 2003 to 2007. Clinical and environmental variables were available for 96 cases and residence data were available for 68 of these cases. Spatial analyses using the global Moran's I and Kulldorff's spatial scan statistic were performed using the population 15 years and younger at both the county and census tract levels to identify those geographic areas at the highest risk of infection.
Two statistically significant (p < 0.05) high-risk clusters, involving six counties, were detected at the county level. At the census tract level, one statistically significant high-risk cluster involving 41 census tracts spanning over six counties was identified. The county level cumulative incidence for those counties in the primary high-risk cluster ranged from 100.0 to 189.0 cases per 100,000 persons (median 189.0) and the census tract level cumulative incidence for those counties in the high-risk cluster ranged from 61.7 to 505.9 cases per 100,000 persons (median 99.0). The counties and census tracts within high-risk clusters had a relative risk four to nine times higher when compared to those areas not contained within high-risk clusters. The majority of LACV infection cases were reported during the summer months in children 15 years and younger. Fever, vomiting, photophobia, and nausea were the most commonly reported signs and symptoms. A case fatality rate (CFR) of 3.1% was observed. Wooded areas and containers were present at the majority of case residences.
The cumulative incidences of LACV infection from 2003 to 2007 were considerably higher than previously reported for West Virginia, and statistically significant high-risk clusters for LACV infection were detected at both the county and census tract levels. The finding of a high CFR and the identification of those areas at highest risk for infection will be useful for guiding future research and intervention efforts.
拉克罗斯病毒（LACV）是美国儿童脑炎的主要病因。自 20 世纪 80 年代中期以来，西弗吉尼亚州报告的 LACV 感染病例数量持续上升，目前该州报告的病例数量居美国之首。本研究旨在调查和描述西弗吉尼亚州报告的 LACV 感染病例的空间流行病学和临床特征，并描述 LACV 感染病例住所的环境条件。
对 2003 年至 2007 年向西弗吉尼亚州卫生部报告的 LACV 感染病例进行描述性和空间分析。对 96 例病例进行了临床和环境变量分析，其中 68 例病例提供了住所数据。在县和普查区两个层面上，使用人群 15 岁及以下年龄进行全局 Moran's I 和 Kulldorff 的空间扫描统计分析，以确定感染风险最高的地理区域。
在县一级检测到两个具有统计学意义（p < 0.05）的高风险集群，涉及六个县。在普查区一级，确定了一个具有统计学意义的高风险集群，涉及跨越六个县的 41 个普查区。主要高风险集群中各县的县级累积发病率为每 10 万人 100.0 至 189.0 例（中位数 189.0），高风险集群中各县的普查区累积发病率为每 10 万人 61.7 至 505.9 例（中位数 99.0）。与不包含在高风险集群中的区域相比，高风险集群内各县和普查区的相对风险为 4 至 9 倍。大多数 LACV 感染病例发生在 15 岁及以下儿童的夏季。发热、呕吐、畏光和恶心是最常见的体征和症状。观察到 3.1%的病例病死率（CFR）。在大多数病例的住所都有树木和容器。
2003 年至 2007 年 LACV 感染的累积发病率明显高于西弗吉尼亚州以前的报告，并且在县和普查区两个层面上都检测到了具有统计学意义的 LACV 感染高危集群。高病死率的发现和确定感染的高危区域将有助于指导未来的研究和干预工作。
