Investigation of clusters of giardiasis using GIS and a spatial scan statistic.
Investigation of clusters of giardiasis using GIS and a spatial scan statistic.
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DOI：
10.1186/1476-072x-3-11
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发表时间：
2004-06-04
影响因子：
4.9
通讯作者：
Wilson J
中科院分区：
文献类型：
--
作者：
Odoi A;Martin SW;Michel P;Middleton D;Holt J;Wilson J
贾第虫是加拿大最常见的人类肠道寄生虫，估计患病率为4- 10%。然而，感染率因地理区域而异，并且认为存在局部高或低感染率的“口袋”。经水传播是主要的感染途径之一。饮用水的污染源包括人类、家畜和野生动物。先前在加拿大安大略南部进行的一项研究表明，贾第虫病发病率与牲畜密度和/或农业用地上的粪肥使用之间存在双变量关联;然而，当将变量“农村”添加到模型中时，这些变量并不显著。在这项研究中，城市地区被界定为人口至少为1 000人、人口密度至少为每平方公里400人的地区;所有其他地区被视为农村地区。本文调查了当地贾第虫病集群的存在，并认为在何种程度上，牲畜密度和粪肥的农业用地上的应用可能会解释“农村”的影响。空间扫描统计被用来确定空间集群和地理相关性分析被用来探索贾第虫病率与农业用地上的粪肥施用和牲畜密度的关联。在一些地区发现了显著（P < 0.05）的高频率空间集群。结果还表明，贾第鞭毛虫病的发病率与牲畜密度和农业用地上的粪便施用量之间存在显著（P < 0.05）的关系。然而，仅在两个地区观察到了这种关联。有证据表明贾第虫病聚集在安大略南部的太空中。然而，没有强有力的证据表明，无论是牲畜密度或粪肥的应用在农业用地上起着重要的作用，贾第虫病的流行病学在研究区域。因此，这些因素似乎不能解释农村地区贾第虫病发病率较高的原因。本研究中使用的空间扫描统计方法在疾病监测中有重要的潜在用途，用于确认或反驳集群警报。
Giardia lamblia is the most frequently identified human intestinal parasite in Canada with prevalence estimates of 4–10%. However, infection rates vary by geographical area and localized 'pockets' of high or low infection rates are thought to exist. Water-borne transmission is one of the major routes of infection. Sources of contamination of drinking water include humans, domestic and wild animals. A previous study in southern Ontario, Canada, indicated a bivariate association between giardiasis rates and livestock density and/or manure use on agricultural land; however these variables were not significant when the variable 'rural' was added to the model. In that study, urban areas were defined as those with a minimum of 1,000 persons and a population density of at least 400 persons per Km2; all other areas were considered rural. This paper investigates the presence of local giardiasis clusters and considers the extent to which livestock density and manure application on agricultural land might explain the 'rural' effect. A spatial scan statistic was used to identify spatial clusters and geographical correlation analysis was used to explore associations of giardiasis rates with manure application on agricultural land and livestock density. Significant (P < 0.05) high rate spatial clusters were identified in a number of areas. Results also showed significant (P < 0.05) associations between giardiasis rates and both livestock density and manure application on agricultural land. However, the associations were observed in only two regions. There is evidence that giardiasis clusters in space in southern Ontario. However, there is no strong evidence to suggest that either livestock density or manure application on agricultural land plays an important role in the epidemiology of giardiasis in the study area. Therefore these factors do not seem to explain the higher rates of giardiasis reported in rural areas. The spatial scan statistics methodology used in this study has an important potential use in disease surveillance for confirming or refuting cluster alarms.