Persistent transmission of Plasmodium malariae and Plasmodium ovale species in an area of declining Plasmodium falciparum transmission in eastern Tanzania
Persistent transmission of Plasmodium malariae and Plasmodium ovale species in an area of declining Plasmodium falciparum transmission in eastern Tanzania
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DOI：
10.1371/journal.pntd.0007414
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发表时间：
2019-05-01
影响因子：
3.8
通讯作者：
Farnert, Anna
中科院分区：
文献类型：
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作者：
Yman, Victor;Wandell, Grace;Farnert, Anna
过去20年来全球疟疾负担的减轻鼓励了区域消除疟疾的努力。尽管需要针对所有疟原虫物种，但目前的重点主要针对恶性疟原虫，并且在较小程度上针对间日疟原虫。关于被忽视的疟疾寄生虫三日疟原虫和卵形疟原虫的全球和地方传播模式的数据严重缺乏。我们使用针对疟原虫18s rRNA基因的物种特异性实时PCR检测来评估坦桑尼亚一个农村22年期间所有人类疟疾寄生虫患病率的时间趋势。我们测试了1994年至2016年期间进行的五次横断面调查中收集的2897份血液样本。恶性疟原虫、三日疟原虫和卵形疟原虫感染在整个研究期间均检测到间日疟原虫，而未检测到间日疟原虫。在1994年至2010年期间，我们发现所有检测到的物种的感染几率降低了90%以上。恶性疟原虫感染的几率在2016年进一步降低，而三日疟原虫和卵形疟原虫的几率则降低。与2010年相比，感染人数分别增加了2倍和6倍。2016年，非恶性疟原虫种属更常发生为单一感染。结果表明卵形疟原虫属的持续传播，以及在较小程度上的三日疟原虫，尽管恶性疟原虫传播持续下降。这表明，非恶性疟原虫物种的传播模式不一定遵循恶性疟原虫的传播模式，强调需要关注非洲的非恶性疟原虫疟疾。消灭疟疾需要更好地了解三日疟原虫和卵形疟原虫的流行病学。并改进了监测所有疟原虫传播的工具，特别侧重于识别无症状感染携带者和设计适当的干预措施，以加强疟疾控制。作者摘要全球疟疾负担的减少鼓励了消除疟疾的努力。控制和监测传播的努力主要集中在主要的疟疾寄生虫恶性疟原虫和间日疟原虫。然而，消除疟疾需要消除所有人类疟疾寄生虫，并且对估计被忽视的疟疾寄生虫卵形疟原虫属的疾病负担的兴趣有限。和三日疟原虫（P.malariae）。作者使用分子方法分析了22年来在5次横断面调查中收集的2897份血液样本，并描述了坦桑尼亚一个村庄中所有人类疟疾寄生虫的传播模式。它们证明了三日疟原虫和卵形疟原虫属的持续传播。尽管恶性疟原虫的传播大幅减少，但疟疾仍在继续，这突出表明需要更多地关注非恶性疟疾。作者讨论了这些研究结果的影响，在目前的努力，区域消除疟疾。
A reduction in the global burden of malaria over the past two decades has encouraged efforts for regional malaria elimination. Despite the need to target all Plasmodium species, current focus is mainly directed towards Plasmodium falciparum, and to a lesser extent P. vivax. There is a substantial lack of data on both global and local transmission patterns of the neglected malaria parasites P. malariae and P. ovale spp. We used a species-specific real-time PCR assay targeting the Plasmodium 18s rRNA gene to evaluate temporal trends in the prevalence of all human malaria parasites over a 22-year period in a rural village in Tanzania.We tested 2897 blood samples collected in five cross-sectional surveys conducted between 1994 and 2016. Infections with P. falciparum, P. malariae, and P. ovale spp. were detected throughout the study period, while P. vivax was not detected. Between 1994 and 2010, we found a more than 90% reduction in the odds of infection with all detected species. The odds of P. falciparum infection was further reduced in 2016, while the odds of P. malariae and P. ovale spp. infection increased 2- and 6-fold, respectively, compared to 2010. In 2016, non-falciparum species occurred more often as mono-infections. The results demonstrate the persistent transmission of P. ovale spp., and to a lesser extent P. malariae despite a continued decline in P. falciparum transmission. This illustrates that the transmission patterns of the non-falciparum species do not necessarily follow those of P. falciparum, stressing the need for attention towards non-falciparum malaria in Africa. Malaria elimination will require a better understanding of the epidemiology of P. malariae and P. ovale spp. and improved tools for monitoring the transmission of all Plasmodium species, with a particular focus towards identifying asymptomatic carriers of infection and designing appropriate interventions to enhance malaria control.Author summary The reduction in the global burden of malaria has encouraged efforts for elimination. Attempts to control and monitor transmission have mainly focused on the predominant malaria parasites Plasmodium falciparum and P. vivax. However, eliminating malaria requires the elimination of all human malaria parasites and limited interest has been directed towards estimating the disease burden attributable to the neglected malaria parasites P. ovale spp. and P. malariae. The authors used molecular methods to analyse 2897 blood samples collected in five cross-sectional surveys over a period of 22 years, and described the transmission patterns of all human malaria parasites in a Tanzanian village. They demonstrate a persistent transmission of P. malariae and P. ovale spp. despite a substantial reduction in transmission of P. falciparum, highlighting the need for more attention towards non-falciparum malaria. The authors discuss the implications of these findings in the context of current efforts for regional malaria elimination.