在埃塞俄比亚一个低疟疾流行地区，通过显微镜检查或快速诊断检测未发现疟原虫血症，但存在恶性疟原虫和间日疟原虫的亚显微携带情况。
Submicroscopic carriage of Plasmodium falciparum and Plasmodium vivax in a low endemic area in Ethiopia where no parasitaemia was detected by microscopy or rapid diagnostic test.
作者信息
Tadesse Fitsum G, Pett Helmi, Baidjoe Amrish, Lanke Kjerstin, Grignard Lynn, Sutherland Colin, Hall Tom, Drakeley Chris, Bousema Teun, Mamo Hassen
机构信息
Department of Medical Microbiology, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525GA, Nijmegen, The Netherlands.
Medical Biotechnology Unit, Institute of Biotechnology, Addis Ababa University, POBox 1176, Addis Ababa, Ethiopia.
出版信息
Malar J. 2015 Aug 5;14:303. doi: 10.1186/s12936-015-0821-1.
BACKGROUND
Motivated by the success in malaria control that was documented over the last decade Ethiopia is aiming at malaria elimination by 2020 in selected districts. It is currently unknown if asymptomatic, submicroscopic malaria parasite carriage may form a hurdle to achieve elimination. The elimination effort may further be complicated by possible glucose-6 phosphate dehydrogenase (G6PD) deficiency which would hinder the use of 8-aminoquinolines in the elimination efforts.
METHOD
In February 2014 a community-based cross-sectional survey was conducted in Malo, southwest Ethiopia. Finger-prick blood samples (n = 555) were tested for presence of Plasmodium falciparum and Plasmodium vivax with microscopy, rapid diagnostic test (RDT), and nested polymerase chain reaction (nPCR). Multiplicity of P. falciparum infections was determined based on genotyping the polymorphic merozoite surface protein-2 (MSP-2) gene. Individuals were also genotyped for mutations in the gene that produces G6PD.
RESULTS
All study participants were malaria infection negative by microscopy and RDT. Nested PCR revealed P. falciparum mono-infection in 5.2% (29/555), P. vivax mono-infection in 4.3% (24/555) and mixed infection in 0.2% (1/555) of individuals. All parasitemic individuals were afebrile (axillary temperature <37.5°C). None of the study participants carried mutations for the G6PD African A-(202GA) and Mediterranean (563CT) variants. All infections, except one, were single-clone infection by MSP-2 genotyping.
CONCLUSION
The detection of a substantial number of subpatent malaria infections in an apparently asymptomatic population without evidence for malaria transmission by conventional diagnostics raises questions about the path to malaria elimination. It is currently unknown how important these infections are for sustaining malaria transmission in the study sites. The absence of G6PD deficiency indicates that 8-aminoquinolines may be safely deployed to accelerate elimination initiatives.
背景
受过去十年疟疾控制取得成功的激励，埃塞俄比亚的目标是到2020年在选定地区消除疟疾。目前尚不清楚无症状、亚显微镜下疟原虫携带是否会成为实现消除疟疾目标的障碍。消除疟疾的努力可能会因可能存在的葡萄糖-6-磷酸脱氢酶（G6PD）缺乏症而进一步复杂化，这会阻碍在消除疟疾工作中使用8-氨基喹啉。
方法
2014年2月，在埃塞俄比亚西南部的马洛开展了一项基于社区的横断面调查。采集手指针刺血样（n = 555），通过显微镜检查、快速诊断检测（RDT）和巢式聚合酶链反应（nPCR）检测恶性疟原虫和间日疟原虫的存在情况。基于对多态性裂殖子表面蛋白-2（MSP-2）基因进行基因分型来确定恶性疟原虫感染的多样性。还对个体产生G6PD的基因中的突变进行基因分型。
结果
通过显微镜检查和RDT，所有研究参与者的疟疾感染均为阴性。巢式PCR显示，5.2%（29/555）的个体为恶性疟原虫单感染，4.3%（24/555）的个体为间日疟原虫单感染，0.2%（1/555）的个体为混合感染。所有有寄生虫血症的个体均无发热（腋温<37.5°C）。研究参与者中没有人为G6PD非洲A-（202GA）和地中海（563CT）变体携带突变。除一例感染外，所有感染通过MSP-2基因分型均为单克隆感染。
结论
在一个明显无症状的人群中检测到大量潜在的疟疾感染，但传统诊断方法未发现疟疾传播的证据，这引发了对疟疾消除途径的质疑。目前尚不清楚这些感染对于研究地点维持疟疾传播有多重要。G6PD缺乏症的不存在表明8-氨基喹啉可安全用于加速消除疟疾的行动。
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