UMR 216-Mère et Enfant Face aux Infections Tropicales, Institut de Recherche pour le Développement, Paris, France.
PLoS One. 2012;7(2):e31100. doi: 10.1371/journal.pone.0031100. Epub 2012 Feb 21.
The objective of this study was to measure the rate of asymptomatic carriage of plasmodium in the Dakar region two years after the implementation of new strategies in clinical malaria management.
Between October and December 2008, 2952 households selected in 50 sites of Dakar area, were visited for interviews and blood sampling. Giemsa-stained thick blood smears (TBS) were performed for microscopy in asymptomatic adult women and children aged 2 to 10 years. To ensure the quality of the microscopy, we performed a polymerase chain reaction (PCR) with real time qPCR in all positive TBS by microscopy and in a sample of negative TBS and filter paper blood spots.
The analysis has concerned 2427 women and 2231 children. The mean age of the women was 35.6 years. The mean age of the children was 5.4 years. The parasite prevalence was 2.01% (49/2427) in women and 2.15% (48/2231) in children. Parasite prevalence varied from one study site to another, ranging from 0 to 7.41%. In multivariate analysis, reporting a malaria episode in 2008 was associated with plasmodium carriage (OR = 2.57, P = 0.002) in women; in children, a malaria episode (OR = 6.19, P<0.001) and a travel out of Dakar during last 3 months (OR = 2.27, P = 0.023) were associated with plasmodium carriage. Among the positive TBS, 95.8% (93/97) were positive by plasmodium PCR. Among the negative TBS, 13.9% (41/293) were positive by PCR. In blood spots, 15.2% (76/500) were positive by PCR. We estimated at 16.5% the parasite prevalence if PCR were performed in 4658 TBS.
Parasite prevalence in Dakar area seemed to be higher than the rate found by microscopy. PCR may be the best tool for measuring plasmodium prevalence in the context of low transmission. Environmental conditions play a major role in the heterogeneity of parasite prevalence within sites.
本研究旨在评估在达喀尔地区实施新的临床疟疾管理策略两年后，无症状疟原虫携带率的变化。
2008 年 10 月至 12 月，在达喀尔地区的 50 个地点选择了 2952 户家庭进行访谈和采血。对无症状成年女性和 2 至 10 岁儿童进行厚血涂片（TBS）吉姆萨染色和显微镜检查。为了确保显微镜检查的质量，我们对所有通过显微镜检查呈阳性的 TBS 和阴性 TBS 及滤纸血斑样本进行了实时聚合酶链反应（PCR）。
共分析了 2427 名女性和 2231 名儿童。女性的平均年龄为 35.6 岁，儿童的平均年龄为 5.4 岁。女性的寄生虫感染率为 2.01%（49/2427），儿童为 2.15%（48/2231）。寄生虫感染率在不同研究地点之间存在差异，范围从 0 到 7.41%。多变量分析显示，2008 年报告疟疾发作与女性疟原虫携带（OR=2.57，P=0.002）相关；儿童疟疾发作（OR=6.19，P<0.001）和过去 3 个月内离开达喀尔（OR=2.27，P=0.023）与疟原虫携带相关。在阳性 TBS 中，95.8%（93/97）通过疟原虫 PCR 呈阳性。在阴性 TBS 中，13.9%（41/293）通过 PCR 呈阳性。在血斑中，15.2%（76/500）通过 PCR 呈阳性。如果在 4658 份 TBS 中进行 PCR 检测，估计寄生虫感染率为 16.5%。
达喀尔地区的寄生虫感染率似乎高于显微镜检查发现的感染率。PCR 可能是在低传播地区测量疟原虫感染率的最佳工具。环境条件在各地点之间寄生虫感染率的异质性中起主要作用。
