加纳不同生态区无症状疟疾病童中恶性疟原虫的种群结构和多样性。

Population structure and diversity of Plasmodium falciparum in children with asymptomatic malaria living in different ecological zones of Ghana.

机构信息

Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.

West Africa Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana.

出版信息

BMC Infect Dis. 2021 May 13;21(1):439. doi: 10.1186/s12879-021-06120-9.

BACKGROUND

Genetic diversity in Plasmodium falciparum populations can be used to describe the resilience and spatial distribution of the parasite in the midst of intensified intervention efforts. This study used microsatellite analysis to evaluate the genetic diversity and population dynamics of P. falciparum parasites circulating in three ecological zones of Ghana.

METHODS

A total of 1168 afebrile children aged between 3 to 13 years were recruited from five (5) Primary schools in 3 different ecological zones (Sahel (Tamale and Kumbungu), Forest (Konongo) and Coastal (Ada and Dodowa)) of Ghana. Asymptomatic malaria parasite carriage was determined using microscopy and PCR, whilst fragment analysis of 6 microsatellite loci was used to determine the diversity and population structure of P. falciparum parasites.

RESULTS

Out of the 1168 samples examined, 16.1 and 39.5% tested positive for P. falciparum by microscopy and nested PCR respectively. The genetic diversity of parasites in the 3 ecological zones was generally high, with an average heterozygosity (He) of 0.804, 0.787 and 0.608 the rainy (peak) season for the Sahel, Forest and Coastal zones respectively. The mean He for the dry (off-peak) season were 0.562, 0.693 and 0.610 for the Sahel, Forest and Coastal zones respectively. Parasites from the Forest zone were more closely related to those from the Sahel than from the Coastal zone, despite the Coastal zone being closer in physical distance to the Forest zone. The fixation indexes among study sites ranged from 0.049 to 0.112 during the rainy season and 0.112 to 0.348 during the dry season.

CONCLUSION

A large asymptomatic parasite reservoir was found in the school children during both rainy and dry seasons, especially those in the Forest and Sahel savannah zones where parasites were also found to be related compared to those from the Coastal zone. Further studies are recommended to understand why despite the roll out of several malaria interventions in Ghana, high transmission still persist.

背景

恶性疟原虫种群的遗传多样性可用于描述寄生虫在强化干预措施中的恢复力和空间分布。本研究使用微卫星分析评估了在加纳三个生态区循环的恶性疟原虫寄生虫的遗传多样性和种群动态。

方法

从加纳三个不同生态区（萨赫勒（塔马利和坎布古）、森林（科农戈）和沿海（阿达和多德瓦））的五所（5）所小学招募了 1168 名 3 至 13 岁的无热儿童。使用显微镜和 PCR 确定无症状疟原虫带虫率，而 6 个微卫星位点的片段分析用于确定恶性疟原虫寄生虫的多样性和种群结构。

结果

在检查的 1168 个样本中，显微镜和巢式 PCR 检测到的恶性疟原虫分别为 16.1%和 39.5%。三个生态区寄生虫的遗传多样性普遍较高，雨（高峰期）季萨赫勒、森林和沿海区的平均杂合度（He）分别为 0.804、0.787 和 0.608。旱（低谷）季的平均 He 分别为 0.562、0.693 和 0.610 萨赫勒、森林和沿海区。尽管沿海区在物理距离上更接近森林区，但来自森林区的寄生虫与来自萨赫勒区的寄生虫比与来自沿海区的寄生虫更密切相关。雨季研究点之间的固定指数范围为 0.049 至 0.112，旱季为 0.112 至 0.348。