Center for Macroecology, Evolution and Climate, Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark.
Malar J. 2011 Oct 11;10:298. doi: 10.1186/1475-2875-10-298.
In Uganda, malaria and lymphatic filariasis (causative agent Wuchereria bancrofti) are transmitted by the same vector species of Anopheles mosquitoes, and thus are likely to share common environmental risk factors and overlap in geographical space. In a comprehensive nationwide survey in 2000-2003 the geographical distribution of W. bancrofti was assessed by screening school-aged children for circulating filarial antigens (CFA). Concurrently, blood smears were examined for malaria parasites. In this study, the resultant malariological data are analysed for the first time and the CFA data re-analysed in order to identify risk factors, produce age-stratified prevalence maps for each infection, and to define the geographical patterns of Plasmodium sp. and W. bancrofti co-endemicity.
Logistic regression models were fitted separately for Plasmodium sp. and W. bancrofti within a Bayesian framework. Models contained covariates representing individual-level demographic effects, school-level environmental effects and location-based random effects. Several models were fitted assuming different random effects to allow for spatial structuring and to capture potential non-linearity in the malaria- and filariasis-environment relation. Model-based risk predictions at unobserved locations were obtained via Bayesian predictive distributions for the best fitting models. Maps of predicted hyper-endemic malaria and filariasis were furthermore overlaid in order to define areas of co-endemicity.
Plasmodium sp. parasitaemia was found to be highly endemic in most of Uganda, with an overall population adjusted parasitaemia risk of 47.2% in the highest risk age-sex group (boys 5-9 years). High W. bancrofti prevalence was predicted for a much more confined area in northern Uganda, with an overall population adjusted infection risk of 7.2% in the highest risk age-group (14-19 year olds). Observed overall prevalence of individual co-infection was 1.1%, and the two infections overlap geographically with an estimated number of 212,975 children aged 5 - 9 years living in hyper-co-endemic transmission areas.
The empirical map of malaria parasitaemia risk for Uganda presented in this paper is the first based on coherent, national survey data, and can serve as a baseline to guide and evaluate the continuous implementation of control activities. Furthermore, geographical areas of overlap with hyper-endemic W. bancrofti transmission have been identified to help provide a better informed platform for integrated control.
在乌干达，疟疾和淋巴丝虫病（病原体为班氏吴策线虫）由同一种疟蚊传播，因此可能具有共同的环境风险因素，并在地理空间上重叠。在 2000-2003 年进行的一次全面全国性调查中，通过筛查学龄儿童的循环丝虫抗原（CFA）来评估班氏吴策线虫的地理分布。同时，还检查了血涂片以检测疟原虫寄生虫。在这项研究中，首次分析了由此产生的疟疾数据，并重新分析了 CFA 数据，以确定风险因素，为每种感染生成年龄分层的患病率地图，并定义疟疾和班氏吴策线虫共同流行的地理模式。
在贝叶斯框架内，分别为疟疾和淋巴丝虫病建立逻辑回归模型。模型包含代表个体水平人口统计学影响、学校水平环境影响和基于位置的随机效应的协变量。拟合了几种模型，假设不同的随机效应以允许空间结构，并捕捉疟疾和丝虫病环境关系中的潜在非线性。通过最佳拟合模型的贝叶斯预测分布获得未观察到的位置的基于模型的风险预测。此外，还将预测的高度流行疟疾和丝虫病地图叠加，以确定共同流行的区域。
在乌干达的大部分地区，疟原虫寄生虫血症被发现高度流行，在最高风险年龄性别组（5-9 岁男孩）中，总人口调整的寄生虫血症风险为 47.2%。在乌干达北部一个更局限的地区，预测到高度流行的班氏吴策线虫感染，在最高风险年龄组（14-19 岁）中，总人口调整的感染风险为 7.2%。观察到的个体合并感染的总体患病率为 1.1%，两种感染在地理上重叠，估计有 212975 名 5-9 岁儿童生活在高度共同流行的传播地区。
本文介绍的乌干达疟疾寄生虫血症风险的实证地图是第一个基于连贯的全国性调查数据的地图，可以作为指导和评估连续实施控制活动的基线。此外，还确定了与高度流行的班氏吴策线虫传播重叠的地理区域，以帮助为综合控制提供更明智的平台。
