Ifakara Health Institutce, Dar-es-Salaam, Tanzania.
Malar J. 2012 Apr 30;11:140. doi: 10.1186/1475-2875-11-140.
Artemisinin-based combination therapy (ACT) has been promoted as a means to reduce malaria transmission due to their ability to kill both asexual blood stages of malaria parasites, which sustain infections over long periods and the immature derived sexual stages responsible for infecting mosquitoes and onward transmission. Early studies reported a temporal association between ACT introduction and reduced malaria transmission in a number of ecological settings. However, these reports have come from areas with low to moderate malaria transmission, been confounded by the presence of other interventions or environmental changes that may have reduced malaria transmission, and have not included a comparison group without ACT. This report presents results from the first large-scale observational study to assess the impact of case management with ACT on population-level measures of malaria endemicity in an area with intense transmission where the benefits of effective infection clearance might be compromised by frequent and repeated re-infection.
A pre-post observational study with a non-randomized comparison group was conducted at two sites in Tanzania. Both sites used sulphadoxine-pyrimethamine (SP) monotherapy as a first-line anti-malarial from mid-2001 through 2002. In 2003, the ACT, artesunate (AS) co-administered with SP (AS + SP), was introduced in all fixed health facilities in the intervention site, including both public and registered non-governmental facilities. Population-level prevalence of Plasmodium falciparum asexual parasitaemia and gametocytaemia were assessed using light microscopy from samples collected during representative household surveys in 2001, 2002, 2004, 2005 and 2006.
Among 37,309 observations included in the analysis, annual asexual parasitaemia prevalence in persons of all ages ranged from 11% to 28% and gametocytaemia prevalence ranged from <1% to 2% between the two sites and across the five survey years. A multivariable logistic regression model was fitted to adjust for age, socioeconomic status, bed net use and rainfall. In the presence of consistently high coverage and efficacy of SP monotherapy and AS + SP in the comparison and intervention areas, the introduction of ACT in the intervention site was associated with a modest reduction in the adjusted asexual parasitaemia prevalence of 5 percentage-points or 23% (p < 0.0001) relative to the comparison site. Gametocytaemia prevalence did not differ significantly (p = 0.30).
The introduction of ACT at fixed health facilities only modestly reduced asexual parasitaemia prevalence. ACT is effective for treatment of uncomplicated malaria and should have substantial public health impact on morbidity and mortality, but is unlikely to reduce malaria transmission substantially in much of sub-Saharan Africa where individuals are rapidly re-infected.
由于青蒿素类复方疗法（ACT）能够杀灭疟原虫的有性和无性血期，而有性血期是疟疾传播的主要来源，因此被认为可以降低疟疾传播。早期的研究报告表明，在一些生态环境中，ACT 的引入与疟疾传播的减少之间存在时间上的关联。然而，这些报告来自疟疾传播率较低或中等的地区，受到其他干预措施或可能降低疟疾传播的环境变化的影响，并且没有包括没有使用 ACT 的对照组。本报告介绍了首次在疟疾传播强度高的地区进行的大规模观察性研究的结果，该研究评估了使用青蒿素类复方疗法进行病例管理对人群疟疾流行程度的影响，在这些地区，频繁和反复的再感染可能会影响有效清除感染的效果。
在坦桑尼亚的两个地点进行了一项无随机对照的预-后观察性研究。两个地点在 2001 年中期至 2002 年期间都使用磺胺多辛-乙胺嘧啶（SP）单药疗法作为一线抗疟药。2003 年，ACT（青蒿琥酯与 SP 联合使用）在干预地点的所有固定卫生机构中引入，包括公共和注册的非政府机构。在 2001 年、2002 年、2004 年、2005 年和 2006 年的代表性家庭调查中，使用显微镜检查法评估人群中疟原虫无性血期寄生虫血症和配子体血症的流行率。
在分析中包含的 37309 个观察结果中，两个地点和五个调查年份中，所有年龄段人群的年无性血期寄生虫血症流行率在 11%至 28%之间，配子体血症流行率在<1%至 2%之间。使用多变量逻辑回归模型调整年龄、社会经济地位、蚊帐使用和降雨量。在 SP 单药疗法和 AS+SP 在对照和干预地区始终保持高覆盖率和疗效的情况下，ACT 在干预地点的引入与对照地点相比，调整后的无性血期寄生虫血症流行率适度降低了 5 个百分点或 23%（p<0.0001）。配子体血症流行率没有显著差异（p=0.30）。
固定卫生机构引入 ACT 仅适度降低了无性血期寄生虫血症的流行率。ACT 对治疗无并发症疟疾有效，应该对发病率和死亡率产生重大的公共卫生影响，但在撒哈拉以南非洲的大部分地区，由于个体迅速再次感染，ACT 不太可能大幅降低疟疾传播。
