Environmental Microbiology Laboratory, University of Puerto Rico, Rio Piedras Campus, San Juan, PR, USA.
Department of Biology, University of Puerto Rico, Rio Piedras Campus, PO Box 23360, San Juan, PR, 00931, USA.
Int Microbiol. 2019 Sep;22(3):337-342. doi: 10.1007/s10123-018-00053-1. Epub 2019 Jan 7.
Malaria is one of the most important human diseases throughout tropical and sub-tropical regions of the world. Global distribution and ample host range have contributed to the genetic diversity of the etiological agent, Plasmodium. Phylogeographical analyses demonstrated that Plasmodium falciparum and Plasmodium vivax follow an Out of Africa (OOA) expansion, having a higher genetic diversity in African populations and a low genetic diversity in South American populations. Modeling the evolutionary rate of conserved genes for both P. falciparum and P. vivax determined the approximate arrival of human malaria in South America. Bayesian computational methods suggest that P. falciparum originated in Africa and arrived in South America through multiple independent introductions by the transatlantic African slave trade; however, in South America, P. vivax could have been introduced through an alternate migratory route. Alignments of P. vivax mitogenomes have revealed low genetic variation between the South American and Southeast Asian populations suggesting introduction through either pre-Columbian human migration or post-colonization events. To confirm the findings of these phylogeographical analyses, molecular methods were used to diagnose malaria infection in archeological remains of pre-Columbian ethnic groups. Immunohistochemistry tests were used and identified P. vivax but not P. falciparum in histologically prepared tissues from pre-Columbian Peruvian mummies, whereas shotgun metagenomics sequencing of DNA isolated from pre-Columbian Caribbean coprolites revealed Plasmodium-homologous reads; current evidence suggests that only P. vivax might have been present in pre-Columbian South America.
疟疾是世界热带和亚热带地区最重要的人类疾病之一。全球分布和充足的宿主范围促成了病原体疟原虫的遗传多样性。系统地理学分析表明，恶性疟原虫和间日疟原虫遵循“走出非洲”（Out of Africa，OOA）扩张模式，在非洲人群中具有更高的遗传多样性，而在南美人群中遗传多样性较低。对恶性疟原虫和间日疟原虫保守基因的进化速率进行建模，确定了人类疟疾传入南美洲的大致时间。贝叶斯计算方法表明，恶性疟原虫起源于非洲，并通过跨大西洋非洲奴隶贸易的多次独立传入到达南美洲；然而，在南美洲，间日疟原虫可能通过另一种迁徙途径传入。对间日疟原虫线粒体基因组的比对揭示了南美和东南亚人群之间遗传变异较低，提示传入途径可能是史前人类迁徙或殖民后事件。为了证实这些系统地理学分析的结果，采用分子方法诊断史前族群的考古遗骸中的疟疾感染。免疫组织化学检测在来自史前秘鲁木乃伊的组织学准备标本中检测到了间日疟原虫，但未检测到恶性疟原虫，而从史前加勒比海粪化石中分离出的 DNA 进行的鸟枪法宏基因组测序显示了疟原虫同源reads；目前的证据表明，只有间日疟原虫可能存在于史前的南美洲。
