Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, Yunnan Province, 650500, China.
Shanglin County People's Hospital, Shanglin, Guangxi, 530500, China.
Travel Med Infect Dis. 2021 Sep-Oct;43:102130. doi: 10.1016/j.tmaid.2021.102130. Epub 2021 Jun 21.
Travel-related malaria in non-endemic areas returning from endemic areas presents important challenges to diagnosis and treatment. Imported malaria to newly malaria-free countries poses further threats of malaria re-introduction and potential resurgence. For those traveling to places with high Plasmodium falciparum prevalence, prophylaxis against this parasite is recommended, whereas causal prophylaxis against relapsing malaria is often overlooked.
We analyzed a cluster of imported malaria among febrile patients in Shanglin County, Guangxi Province, China, who had recent travel histories to Western and Central Africa. Malaria was diagnosed by microscopy and subsequently confirmed by species- and subspecies-specific PCR. Plasmodium vivax was genotyped using a barcode consisting of 42 single nucleotide polymorphisms.
Investigations of 344 PCR-confirmed malaria cases revealed that in addition to Plasmodium falciparum being the major parasite species, the relapsing parasites Plasmodium ovale and P. vivax accounted for ~40% of these imported cases. Of the 114 P. ovale infections, 65.8% and 34.2% were P. ovale curtisi and P. ovale wallikeri, respectively, with the two subspecies having a ~2:1 ratio in both Western and Central Africa. Phylogenetic analysis of 14 P. vivax isolates using a genetic barcode demonstrated that 11 formed a distinct clade from P. vivax populations from Eastern Africa.
This study provides support for active P. vivax transmission in areas with the predominant Duffy-negative blood group. With relapsing malaria making a substantial proportion of the imported malaria, causal prophylaxis should be advocated to travelers with a travel destination to Western and Central Africa.
从流行地区返回非流行地区的旅行者疟疾对诊断和治疗提出了重要挑战。输入性疟疾对新无疟疾国家构成了疟疾再次输入和潜在死灰复燃的进一步威胁。对于前往恶性疟原虫流行地区的旅行者，建议预防这种寄生虫感染，但往往忽视针对复发性疟疾的病因预防。
我们分析了广西上林县 344 例有近期前往西非和中非旅行史的发热患者的输入性疟疾聚集病例。通过显微镜检查诊断疟疾，随后通过种和亚种特异性 PCR 进行确认。采用由 42 个单核苷酸多态性组成的条码对间日疟原虫进行基因分型。
对 344 例 PCR 确诊的疟疾病例的调查显示，除恶性疟原虫是主要寄生虫物种外，复发寄生虫卵形疟原虫和间日疟原虫约占这些输入性病例的 40%。在 114 例卵形疟原虫感染中，65.8%和 34.2%分别为卵形疟原虫 curtisi 和卵形疟原虫 wallikeri，两种亚种在西非和中非的比例约为 2:1。使用遗传条码对 14 株间日疟原虫分离株进行的系统发育分析表明，11 株与来自东非的间日疟原虫种群形成一个独特的分支。
本研究为主要存在阴性 Duffy 血型人群中存在活跃的间日疟传播提供了依据。由于复发性疟疾在输入性疟疾中占很大比例，因此应向前往西非和中非的旅行者提倡病因预防。
