Rabarijaona L, Rakotomanana F, Ranaivo L, Raharimalala L, Modiano D, Boisier P, De Giorgi F, Raveloson N, Jambou R
Pasteur Institute of Madagascar, University of Rome, Italy.
Trans R Soc Trop Med Hyg. 2001 May-Jun;95(3):267-9. doi: 10.1016/s0035-9203(01)90230-5.
To control the reappearance of malaria in the Madagascan highlands, indoor house-spraying of DDT was conducted from 1993 until 1998. Before the end of the insecticide-spraying programme, a surveillance system was set up to allow rapid identification of new malaria epidemics. When the number of suspected clinical malaria cases notified to the surveillance system exceeds a predetermined threshold, a parasitological survey is carried out in the community to confirm whether or not transmission of falciparum malaria is increasing. Owing to the low specificity of the surveillance system, this confirmation stage is essential to guide the activities of the control programme. For this purpose, Lot Quality Assurance Sampling (LQAS), which usually requires smaller sample sizes, seemed to be a valuable alternative to conventional survey methods. In parallel to a conventional study of Plasmodium falciparum prevalence carried out in 1998, we investigated the ability of LQAS to rapidly classify zones according to a predetermined prevalence level. Two prevalence thresholds (5% and 15%) were tested using various sampling plans. A plan (36, 2), meaning that at least 2 individuals found to be positive among a random sample of 36, enabled us to classify a community correctly with a sensitivity of 100% and a specificity of 94%. LQAS is an effective tool for rapid assessment of falciparum malaria prevalence when monitoring malaria transmission.
为控制马达加斯加高地疟疾的再度出现，1993年至1998年期间开展了室内喷洒滴滴涕的工作。在杀虫剂喷洒计划结束前，建立了一个监测系统，以便能够迅速识别新的疟疾疫情。当通报给监测系统的疑似临床疟疾病例数量超过预定阈值时，就在社区开展寄生虫学调查，以确认恶性疟的传播是否正在增加。由于监测系统的特异性较低，这一确认阶段对于指导控制计划的活动至关重要。为此，通常所需样本量较小的批质量保证抽样法（LQAS）似乎是传统调查方法的一个有价值的替代方法。在1998年对恶性疟原虫流行情况进行常规研究的同时，我们调查了LQAS根据预定流行水平快速对区域进行分类的能力。使用各种抽样方案测试了两个流行阈值（5%和15%）。一个方案（36, 2），即从36个随机样本中至少发现2个呈阳性，使我们能够以100%的灵敏度和94%的特异性正确地对一个社区进行分类。在监测疟疾传播时，LQAS是快速评估恶性疟流行情况的有效工具。
