Department of Parasitology, Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan.
PLoS One. 2011 Feb 23;6(2):e16948. doi: 10.1371/journal.pone.0016948.
Identifying the location and size of residual foci of infections is critical where malaria elimination is the primary goal. Here the spatial heterogeneity of Plasmodium falciparum infections within the urban extent of Khartoum state in Sudan is investigated using data from cross-sectional surveys undertaken from 1999 to 2008 to inform the Khartoum Malaria Free Initiative (KMFI).
From 1999-2008 the KMFI undertook cross-sectional surveys of 256 clusters across 203 random samples of residential blocks in the urban Khartoum state in September of each year. Within sampled blocks, at least five persons, including at least one child under the age of five years, were selected from each household. Blood smears were collected from the sampled individuals to examine the presence of P. falciparum parasites. Residential blocks were mapped. Data were analysed for spatial clustering using the Bernoulli model and the significance of clusters were tested using the Kulldorff scan statistic.
A total of 128,510 malaria slide examinations were undertaken during the study period. In 1999, overall prevalence was 2.5%, rising to 3.2% in 2000 and consistently staying below 1% in subsequent years. From 2006, over 90% of all surveyed clusters reported no infections. Spatial clustering of infections was present in each year but not statistically significant in the years 2001, 2002, 2004 and 2008. Spatial clusters of high infection were often located at the junction of the Blue and White Niles.
Persisting foci of malaria infection in Khartoum are likely to distort wide area assessments and disproportionately affect future transmission within the city limits. Improved investments in surveillance that combines both passive and active case detection linked to a geographic information system and a more detailed analysis of the location and stability of foci should be undertaken to facilitate and track malaria elimination in the state of Khartoum.
在以消除疟疾为主要目标的地区，确定感染灶的位置和大小至关重要。本研究利用 1999 年至 2008 年期间开展的横断面调查数据，调查了苏丹喀土穆州城市范围内间日疟原虫感染的空间异质性，该调查旨在为喀土穆消除疟疾倡议（KMFI）提供信息。
1999 年至 2008 年期间，KMFI 在每年 9 月对喀土穆州城市地区 203 个随机居住街区的 256 个街区进行了横断面调查。在抽样街区内，每个家庭至少选择 5 人，包括至少 1 名 5 岁以下儿童。采集被抽样个体的血样，检查是否存在恶性疟原虫寄生虫。对居住街区进行了绘图。使用伯努利模型对数据进行空间聚类分析，并使用 Kulldorff 扫描统计检验对聚类的显著性进行检验。
在研究期间共进行了 128510 次疟疾涂片检查。1999 年总体患病率为 2.5%，2000 年上升至 3.2%，随后连续几年保持在 1%以下。自 2006 年以来，超过 90%的调查街区报告无感染。每年均存在感染的空间聚类，但在 2001 年、2002 年、2004 年和 2008 年并不具有统计学意义。高感染的空间聚类通常位于青尼罗河和白尼罗河的交汇处。
喀土穆持续存在的疟疾感染灶可能会扭曲大面积评估，并不成比例地影响城市范围内的未来传播。应加强投资，开展结合被动和主动病例发现的监测工作，将其与地理信息系统相联系，并对感染灶的位置和稳定性进行更详细的分析，以促进和跟踪喀土穆州的疟疾消除工作。
