Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo.
Malar J. 2011 Oct 18;10:308. doi: 10.1186/1475-2875-10-308.
External quality assessments (EQA) are an alternative to cross-checking of blood slides in the quality control of malaria microscopy. This study reports the findings of an EQA of malaria microscopy in the Democratic Republic of the Congo (DRC).
After validation, an EQA slide panel and a questionnaire were delivered to diagnostic laboratories in four provinces of DRC. The panel included three samples for diagnosis (sample 1: Plasmodium falciparum, 177,000/μl, sample 2: P. falciparum, 2,500/μl, sample 3: no parasites seen), one didactic sample (Howell-Jolly bodies) and one sample for assessing the quality of staining. Participating laboratories were addressed and selected through the network of the National Tuberculosis Control Programme. Participants were asked to return the responses together with a stained thin and thick blood film for evaluation of Giemsa stain quality.
Among 174 participants (response rate 95.1%), 26.2% scored samples 1, 2 and 3 correctly and 34.3%, 21.5% and 5.8% of participants reported major errors in one, two or three samples respectively. Major errors included reporting "no malaria" or "non-falciparum malaria" for Plasmodium falciparum-positive samples 1 and 2 (16.1% and 34.9% of participants respectively) and "P. falciparum" for Plasmodium negative sample 3 (24.0%). Howell-Jolly bodies (didactic sample) were not recognized by any of the participants but reported as "P. falciparum" by 16.7% of participants. With parasite density expressed according to the "plus system", 16.1% and 21.5% of participants scored one "+" different from the reference score for samples 1 and 2 respectively and 9.7% and 2.9% participants scored more than two "+" different. When expressed as counts of asexual parasites/μl, more than two-thirds of results were outside the mean ± 2SD reference values. The quality of the Giemsa stain was poor, with less than 20% slides complying with all criteria assessed. Only one quarter of participants purchase Giemsa stain from suppliers of documented reliability and half of participants use a buffered staining solution. One third of participants had participated in a formal training about malaria diagnosis, half of them earlier than 2007.
The present EQA revealed a poor quality of malaria microscopy in DRC.
外部质量评估（EQA）是疟疾显微镜检查质量控制中交叉检查血片的替代方法。本研究报告了刚果民主共和国（DRC）疟疾显微镜检查的 EQA 结果。
经过验证后，EQA 幻灯片面板和问卷被送到 DRC 的四个省的诊断实验室。该面板包括三个用于诊断的样本（样本 1：恶性疟原虫，177,000/μl，样本 2：恶性疟原虫，2,500/μl，样本 3：未见寄生虫），一个教学样本（Howell-Jolly 体）和一个用于评估染色质量的样本。通过国家结核病控制规划网络联系并选择参与实验室。要求参与者将回复与染色的薄血涂片和厚血涂片一起返回，以评估吉姆萨染色质量。
在 174 名参与者中（回应率 95.1%），26.2%正确地标记了样本 1、2 和 3，34.3%、21.5%和 5.8%的参与者分别在一个、两个或三个样本中报告了主要错误。主要错误包括对样本 1 和 2 的恶性疟原虫阳性样本报告“无疟疾”或“非恶性疟原虫疟疾”（分别为 16.1%和 34.9%的参与者）和对样本 3 的恶性疟原虫阴性样本报告“恶性疟原虫”（24.0%的参与者）。没有人识别出 Howell-Jolly 体（教学样本），但 16.7%的参与者将其报告为“恶性疟原虫”。根据“加号系统”表示寄生虫密度时，样本 1 和 2 的 16.1%和 21.5%的参与者评分与参考评分相差一个“+”，而 9.7%和 2.9%的参与者评分相差两个以上“+”。当以无性寄生虫/μl 的数量表示时，三分之二以上的结果超出了均值±2SD 的参考值。吉姆萨染色质量差，不到 20%的载玻片符合所有评估标准。只有四分之一的参与者从有记录可靠性的供应商处购买吉姆萨染色剂，一半的参与者使用缓冲染色溶液。三分之一的参与者参加过疟疾诊断的正式培训，其中一半人是在 2007 年之前参加的。
本次 EQA 显示刚果民主共和国的疟疾显微镜检查质量较差。
