Erkenswick Gideon A, Watsa Mrinalini, Pacheco M Andreína, Escalante Ananias A, Parker Patricia G
Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, Saint Louis, Missouri, United States of America.
Field Projects International, Saint Louis, Missouri, United States of America.
PLoS One. 2017 Sep 13;12(9):e0184504. doi: 10.1371/journal.pone.0184504. eCollection 2017.
There is an increased interest in potential zoonotic malarias. To date, Plasmodium malariae that infects humans remains indistinguishable from Plasmodium brasilianum, which is widespread among New World primates. Distributed throughout tropical Central and South America, the Callitrichidae are small arboreal primates in which detection of natural Plasmodium infection has been extremely rare. Most prior screening efforts have been limited to small samples, the use of low-probability detection methods, or both. Rarely have screening efforts implemented a longitudinal sampling design. Through an annual mark-recapture program of two sympatric callitrichids, the emperor (Saguinus imperator) and saddleback (Saguinus fuscicollis) tamarins, whole blood samples were screened for Plasmodium by microscopy and nested PCR of the cytochrome b gene across four consecutive years (2012-2015). Following the first field season, approximately 50% of the samples collected each subsequent year were from recaptured individuals. In particular, out of 245 samples from 129 individuals, 11 samples from 6 individuals were positive for Plasmodium, and all but one of these infections was found in S. imperator. Importantly, the cytochrome b sequences were 100% identical to former isolates of P. malariae from humans and P. brasilianum from Saimiri sp. Chronic infections were detected as evidenced by repeated infections (7) from two individuals across the 4-year study period. Furthermore, 4 of the 5 infected emperor tamarins were part of a single group spanning the entire study period. Overall, the low prevalence reported here is consistent with previous findings. This study identifies two new natural hosts for P. brasilianum and provides evidence in support of chronic infections in wildlife populations. Given that callitrichids are often found in mixed-species associations with other primates and can be resilient to human-disturbed environments, they could contribute to the maintenance of P. malariae populations if future work provides entomological and epidemiological evidence indicating human zoonotic infections.
人们对潜在的人畜共患疟疾越来越感兴趣。迄今为止，感染人类的疟原虫与在新大陆灵长类动物中广泛存在的巴西疟原虫仍无法区分。狨科动物分布于热带中美洲和南美洲，是小型树栖灵长类动物，在它们身上极少检测到自然感染的疟原虫。此前大多数筛查工作都局限于小样本、使用低概率检测方法，或两者兼而有之。筛查工作很少采用纵向抽样设计。通过对两种同域分布的狨科动物——棉顶狨（Saguinus imperator）和鞍背狨（Saguinus fuscicollis）进行年度标记重捕计划，连续四年（2012 - 2015年）通过显微镜检查和细胞色素b基因的巢式PCR对全血样本进行疟原虫筛查。在第一个野外季节之后，随后每年收集的样本中约50%来自重新捕获的个体。具体而言，在来自129个个体的245个样本中，有6个个体的11个样本疟原虫呈阳性，其中除一例之外，所有感染均在棉顶狨中发现。重要的是，细胞色素b序列与先前来自人类的疟原虫分离株以及来自松鼠猴属的巴西疟原虫分离株100%相同。在为期4年的研究期间，两名个体反复感染（7次），证明存在慢性感染。此外，5只感染的棉顶狨中有4只属于跨越整个研究期间的单个群体。总体而言，这里报告的低患病率与先前的研究结果一致。本研究确定了巴西疟原虫的两个新自然宿主，并为野生动物种群中的慢性感染提供了支持证据。鉴于狨科动物经常与其他灵长类动物形成混合物种群落，并且能够适应人类干扰的环境，如果未来的研究提供昆虫学和流行病学证据表明存在人类人畜共患感染，它们可能有助于维持疟原虫种群。
