London School of Hygiene and Tropical Medicine, London, UK.
Ifakara Institute of Health, Bagamoyo Research and Training Centre, Bagamoyo District Hospital, P.O. Box 74, Bagamoyo, Tanzania.
Malar J. 2017 Oct 27;16(1):433. doi: 10.1186/s12936-017-2078-3.
Plasmodium falciparum prevalence (PfPR) is a widely used metric for assessing malaria transmission intensity. This study was carried out concurrently with the RTS,S/AS01 candidate malaria vaccine Phase III trial and estimated PfPR over ≤ 4 standardized cross-sectional surveys.
This epidemiology study (NCT01190202) was conducted in 8 sites from 6 countries (Burkina Faso, Gabon, Ghana, Kenya, Malawi, and Tanzania), between March 2011 and December 2013. Participants were enrolled in a 2:1:1 ratio according to age category: 6 months-4 years, 5-19 years, and ≥ 20 years, respectively, per year and per centre. All sites carried out surveys 1-3 while survey 4 was conducted only in 3 sites. Surveys were usually performed during the peak malaria parasite transmission season, in one home visit, when medical history and malaria risk factors/prevention measures were collected, and a blood sample taken for rapid diagnostic test, microscopy, and haemoglobin measurement. PfPR was estimated by site and age category.
Overall, 6401 (survey 1), 6411 (survey 2), 6400 (survey 3), and 2399 (survey 4) individuals were included in the analyses. In the 6 months-4 years age group, the lowest prevalence (assessed using microscopy) was observed in 2 Tanzanian centres (4.6% for Korogwe and 9.95% for Bagamoyo) and Lambaréné, Gabon (6.0%), while the highest PfPR was recorded for Nanoro, Burkina Faso (52.5%). PfPR significantly decreased over the 3 years in Agogo (Ghana), Kombewa (Kenya), Lilongwe (Malawi), and Bagamoyo (Tanzania), and a trend for increased PfPR was observed over the 4 surveys for Kintampo, Ghana. Over the 4 surveys, for all sites, PfPR was predominantly higher in the 5-19 years group than in the other age categories. Occurrence of fever and anaemia was associated with high P. falciparum parasitaemia. Univariate analyses showed a significant association of anti-malarial treatment in 4 surveys (odds ratios [ORs]: 0.52, 0.52, 0.68, 0.41) and bed net use in 2 surveys (ORs: 0.63, 0.68, 1.03, 1.78) with lower risk of malaria infection.
Local PfPR differed substantially between sites and age groups. In children 6 months-4 years old, a significant decrease in prevalence over the 3 years was observed in 4 out of the 8 study sites. Trial registration Clinical Trials.gov identifier: NCT01190202:NCT. GSK Study ID numbers: 114001.
恶性疟原虫流行率（PfPR）是评估疟疾传播强度的常用指标。本研究与 RTS,S/AS01 候选疟疾疫苗 III 期临床试验同时进行，在 4 项标准化横断面研究中进行了PfPR 估计。
这项流行病学研究（NCT01190202）于 2011 年 3 月至 2013 年 12 月在 6 个国家（布基纳法索、加蓬、加纳、肯尼亚、马拉维和坦桑尼亚）的 8 个地点进行。根据年龄类别以 2:1:1 的比例招募参与者：每年和每个中心分别为 6 个月至 4 岁、5-19 岁和≥20 岁。所有地点均进行了 1-3 项调查，而第 4 项调查仅在 3 个地点进行。调查通常在疟疾寄生虫传播高峰期进行，在一次家访中进行，收集病史和疟疾风险因素/预防措施，并采集血液样本进行快速诊断测试、显微镜检查和血红蛋白测量。PfPR 按地点和年龄类别进行估计。
总体而言，共有 6401 人（调查 1）、6411 人（调查 2）、6400 人（调查 3）和 2399 人（调查 4）纳入分析。在 6 个月至 4 岁年龄组中，在 2 个坦桑尼亚中心（科罗韦的 4.6%和巴加莫约的 9.95%）和加蓬的兰巴雷内（6.0%）观察到最低的患病率（通过显微镜评估），而布基纳法索的纳诺罗记录了最高的 PfPR（52.5%）。在 3 年内，Agogo（加纳）、Kombewa（肯尼亚）、Lilongwe（马拉维）和 Bagamoyo（坦桑尼亚）的 PfPR 显著下降，而 Kintampo（加纳）的 PfPR 在 4 项调查中呈上升趋势。在 4 项调查中，对于所有地点，5-19 岁年龄组的 PfPR 明显高于其他年龄组。发热和贫血的发生与恶性疟原虫寄生虫血症有关。单因素分析显示，在 4 项调查中（比值比 [OR]：0.52、0.52、0.68、0.41）和 2 项调查中（OR：0.63、0.68、1.03、1.78）使用抗疟药物治疗与疟疾感染风险降低显著相关。
不同地点和年龄组之间的本地 PfPR 存在很大差异。在 6 个月至 4 岁的儿童中，在 8 个研究地点中的 4 个观察到 PfPR 在 3 年内显著下降。临床试验注册临床试验.gov 标识符：NCT01190202：NCT。GSK 研究编号：114001。
