Alves Fabiana P, Durlacher Rui R, Menezes Maria J, Krieger Henrique, Silva Luiz H Pereira, Camargo Erney P
Department of Parasitology, University of São Paulo, São Paulo, Brazil.
Am J Trop Med Hyg. 2002 Jun;66(6):641-8. doi: 10.4269/ajtmh.2002.66.641.
The epidemiology of malaria in 2 riverine localities in Rondĵnia, Brazilian western Amazĵnia, was assessed by a 1-year study at Portuchuelo, and a cross-sectional survey at riverine communities at Rio Machado (= Ji-Parana). Plasmodium spp. infections were diagnosed by light microscopy and by polymerase chain reaction (PCR) amplification of ribosomal DNA. PCR was 6-7 times more efficient than microscopy for detecting plasmodial infections. Both Plasmodium vivax and Plasmodium falciparum infections occurred as asymptomatic and symptomatic forms of the disease. The relation between symptomatic and asymptomatic clinical forms was roughly similar for both species of Plasmodium. Symptomless patients were monitored for 2 months. The prevalence of symptomless infections was 4-5 times higher than the symptomatic ones--respectively, 20% and 4.6% for Portuchuelo and 49.5% and 10% for Ji-Parana. Symptomatic malaria occurred mostly in patients in younger age groups. In contrast, there was a significant association of symptomless malaria with older age groups (medians of 26.5 and 21 years, respectively, for Portuchuelo and Ji-Parana), whereas the age medians for symptomatic malaria were 14 and 8 years, respectively, in the 2 regions. Symptomatic malaria also was more prevalent in groups living for shorter times in Amazĵnia (13 and 4 years, respectively, for Portuchuelo and Ji-ParanA) as compared with symptomless malaria, which was more prevalent in groups living for longer periods in the region (medians of 25.5 and 18 years, respectively, for Portuchuelo and Ji-Paraná). The high prevalence of symptomless malaria may pose new problems for the currently adopted strategy for the control of malaria in the Amazonian region, which is essentially based on the treatment of symptomatic patients.
通过在波图乔埃洛进行的为期1年的研究以及在马查多河（= 济帕拉纳）沿岸社区开展的横断面调查，对巴西亚马孙西部地区朗多尼亚州两个河滨地区的疟疾流行病学情况进行了评估。疟原虫属感染通过光学显微镜检查以及核糖体DNA的聚合酶链反应（PCR）扩增来诊断。在检测疟原虫感染方面，PCR的效率比显微镜检查高6至7倍。间日疟原虫和恶性疟原虫感染均有无症状和有症状两种形式。两种疟原虫的有症状和无症状临床形式之间的关系大致相似。对无症状患者进行了2个月的监测。无症状感染的患病率比有症状感染高4至5倍——在波图乔埃洛分别为20%和4.6%，在济帕拉纳分别为49.5%和10%。有症状疟疾大多发生在较年轻年龄组的患者中。相比之下，无症状疟疾与较年长年龄组存在显著关联（在波图乔埃洛和济帕拉纳的年龄中位数分别为26.5岁和21岁），而在这两个地区，有症状疟疾的年龄中位数分别为14岁和8岁。与无症状疟疾相比，有症状疟疾在亚马孙地区居住时间较短的人群中也更为普遍（在波图乔埃洛和济帕拉纳分别为13年和4年），无症状疟疾在该地区居住时间较长的人群中更为普遍（在波图乔埃洛和济帕拉纳的年龄中位数分别为25.5岁和18岁）。无症状疟疾的高患病率可能给目前在亚马孙地区采用的疟疾控制策略带来新问题，该策略主要基于对有症状患者的治疗。
