Department of Parasitology, Institute of Tropical Medicine, Antwerp, Belgium.
PLoS One. 2011 Jan 28;6(1):e16257. doi: 10.1371/journal.pone.0016257.
There is an increasing body of literature reporting treatment failure of the currently recommended radical treatment of Plasmodium vivax infections. As P. vivax is the main malaria species outside the African continent, emerging tolerance to its radical treatment regime could have major consequences in countries like Peru, where 80% of malaria cases are due to P. vivax. Here we describe the results of a 1-year longitudinal follow up of 51 confirmed P. vivax patients living around Iquitos, Peruvian Amazon, and treated according to the Peruvian national guidelines.
Each month a blood sample for microscopy and later genotyping was systematically collected. Recent exposure to infection was estimated by detecting antibodies against the P. vivax circumsporozoite protein (CSP) and all PCR confirmed P. vivax infections were genotyped with 16 polymorphic microsatellites.
During a 1-year period, 84 recurrent infections, 22 positive also by microscopy, were identified, with a median survival time to first recurrent infection of 203 days. Most of them (71%) were asymptomatic; in 13 patients the infection persisted undetected by microscopy for several consecutive months. The genotype of mostly recurrent infections differed from that at day 0 while fewer differences were seen between the recurrent infections. The average expected heterozygosity was 0.56. There was strong linkage disequilibrium (I(A)(s) = 0.29, p<1.10(-4)) that remained also when analyzing only the unique haplotypes, suggesting common inbreeding.
In Peru, the P. vivax recurrent infections were common and displayed a high turnover of parasite genotypes compared to day 0. Plasmodium vivax patients, even when treated according to the national guidelines, may still represent an important parasite reservoir that can maintain transmission. Any elimination effort should consider such a hidden reservoir.
越来越多的文献报道，目前推荐的根治性治疗间日疟原虫感染的方法治疗失败。由于间日疟原虫是非洲大陆以外地区的主要疟疾物种，对其根治性治疗方案产生耐药性可能会在秘鲁等国家产生重大影响，秘鲁 80%的疟疾病例都是由间日疟原虫引起的。在这里，我们描述了对居住在秘鲁亚马逊伊基托斯周围的 51 例确诊间日疟原虫患者进行为期 1 年的纵向随访结果，这些患者按照秘鲁国家指南进行治疗。
每月系统采集一份血样进行显微镜检查和基因分型。通过检测对间日疟原虫环子孢子蛋白（CSP）的抗体来估计近期感染情况，所有通过 PCR 确认的间日疟原虫感染均采用 16 个多态性微卫星进行基因分型。
在 1 年期间，共发现 84 例复发性感染，其中 22 例也通过显微镜检查阳性，首次复发性感染的中位生存时间为 203 天。其中大多数（71%）为无症状感染；在 13 例患者中，感染在连续几个月内未被显微镜检查发现。大多数复发性感染的基因型与第 0 天不同，而复发性感染之间的差异较小。平均预期杂合度为 0.56。存在强烈的连锁不平衡（I(A)(s) = 0.29，p<1.10(-4)），当仅分析唯一的单倍型时仍然存在，这表明存在共同近亲繁殖。
在秘鲁，间日疟原虫的复发性感染很常见，与第 0 天相比，寄生虫基因型的更替率很高。即使按照国家指南进行治疗，间日疟原虫患者仍可能代表一个重要的寄生虫储存库，从而维持传播。任何消除疟疾的努力都应该考虑到这种隐藏的寄生虫储存库。
