A large focus of naturally acquired Plasmodium knowlesi infections in human beings
A large focus of naturally acquired Plasmodium knowlesi infections in human beings
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DOI：
10.1016/s0140-6736(04)15836-4
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发表时间：
2004-03-27
期刊：
影响因子：
168.9
通讯作者：
Conway, DJ
中科院分区：
文献类型：
--
作者：
Singh, B;Sung, LK;Conway, DJ
背景 1999 年，马来西亚婆罗洲加帛区约五分之一的疟疾病例通常通过显微镜检查被鉴定为三日疟原虫，尽管这些感染看起来不典型，并且巢式 PCR 检测未能鉴定出三日疟原虫 DNA。我们的目的是调查此类感染是否可归因于疟原虫的变异形式或新出现的疟原虫物种。方法我们从 2000 年 3 月至 2002 年 11 月期间从 Kapit 区的 208 名疟疾患者采集了血液样本。对经显微镜鉴定为疟原虫的 8 个分离株的小亚基核糖体 RNA 和环子孢子蛋白基因进行了测序。所有血液样本均采用属特异性和种特异性巢式 PCR 检测以及新设计的诺氏疟原虫特异性引物进行表征。研究结果所有 DNA 序列在系统发育上与诺氏疟原虫（一种长尾猕猴的疟疾寄生虫）的 DNA 序列无法区分，但与其他疟疾寄生虫物种显着不同。通过 PCR 检测，208 名疟疾患者中有 120 名（58%）诺氏疟原虫检测呈阳性，而三日疟原虫均未呈阳性。通过显微镜很难将人类红细胞中的诺氏疟原虫与三日疟原虫区分开来。大多数诺氏疟原虫感染是成年人，我们没有注意到社区内出现任何聚集性病例。氯喹和伯氨喹成功治疗了诺氏疟原虫感染。解释自然获得性诺氏疟原虫感染主要通过显微镜误诊为三日疟，在我们的研究中占所有疟疾病例的一半以上。诺氏疟原虫和三日疟原虫之间的形态相似性需要使用分子方法进行正确识别。需要进一步的工作来确定卡皮特科的人类诺氏疟原虫感染是否是从猕猴获得的，或者是否发生了宿主向人类的转变。
Background About a fifth of malaria cases in 1999 for the Kapit division of Malaysian Borneo had routinely been identified by microscopy as Plasmodium malariae, although these infections appeared atypical and a nested PCR assay failed to identify P malariae DNA. We aimed to investigate whether such infections could be attributable to a variant form of P malariae or a newly emergent Plasmodium species.Methods We took blood samples from 208 people with malaria in the Kapit division between March, 2000, and November, 2002. The small subunit ribosomal RNA and the circumsporozoite protein genes were sequenced for eight isolates that had been microscopically identified as P malariae. All blood samples were characterised with a genus-specific and species-specific nested PCR assay together with newly designed P knowlesi-specific primers.Findings All DNA sequences were phylogenetically indistinguishable from those of P knowlesi, a malaria parasite of long-tailed macaque monkeys, but were significantly different from other malaria parasite species. By PCR assay, 120 (58%) of 208 people with malaria tested positive for P knowlesi, whereas none was positive for P malariae. P knowlesi parasites in human erythrocytes were difficult to distinguish from P malariae by microscopy. Most of the P knowlesi infections were in adults and we did not note any clustering of cases within communities. P knowlesi infections were successfully treated with chloroquine and primaquine.Interpretation Naturally acquired P knowlesi infections, misdiagnosed by microscopy mainly as P malariae, accounted for over half of all malaria cases in our study. Morphological similarities between P knowlesi and P malariae necessitate the use of molecular methods for correct identification. Further work is needed to determine whether human P knowlesi infections in the Kapit division are acquired from macaque monkeys or whether a host switch to human beings has occurred.