Centro de Pesquisas Gonçalo Moniz, Fundação Oswaldo Cruz, Salvador, Brazil.
PLoS One. 2011;6(5):e19841. doi: 10.1371/journal.pone.0019841. Epub 2011 May 18.
Areas that are endemic for malaria are also highly endemic for hepatitis B virus (HBV) infection. Nevertheless, it is unknown whether HBV infection modifies the clinical presentation of malaria. This study aimed to address this question.
An observational study of 636 individuals was performed in Rondônia, western Amazon, Brazil between 2006 and 2007. Active and passive case detections identified Plasmodium infection by field microscopy and nested Polymerase Chain Reaction (PCR). HBV infections were identified by serology and confirmed by real-time PCR. Epidemiological information and plasma cytokine profiles were studied. The data were analyzed using adjusted multinomial logistic regression. Plasmodium-infected individuals with active HBV infection were more likely to be asymptomatic (OR: 120.13, P<0.0001), present with lower levels of parasitemia and demonstrate a decreased inflammatory cytokine profile. Nevertheless, co-infected individuals presented higher HBV viremia. Plasmodium parasitemia inversely correlated with plasma HBV DNA levels (r = -0.6; P = 0.0003).
HBV infection diminishes the intensity of malaria infection in individuals from this endemic area. This effect seems related to cytokine balance and control of inflammatory responses. These findings add important insights to the understanding of the factors affecting the clinical outcomes of malaria in endemic regions.
疟疾流行地区也是乙型肝炎病毒（HBV）感染的高度流行地区。然而，HBV 感染是否会改变疟疾的临床特征尚不清楚。本研究旨在探讨这一问题。
2006 年至 2007 年，在巴西亚马逊西部的朗多尼亚州进行了一项针对 636 人的观察性研究。通过现场显微镜检查和巢式聚合酶链反应（PCR）对活动性和被动性病例检测，确定疟原虫感染。通过血清学检测和实时 PCR 确认 HBV 感染。研究了流行病学信息和血浆细胞因子谱。使用调整后的多项逻辑回归分析数据。与无 HBV 感染的疟原虫感染者相比，活动性 HBV 感染者更有可能无症状（OR：120.13，P<0.0001），寄生虫血症水平较低，炎症细胞因子谱降低。然而，合并感染的个体 HBV 病毒载量更高。疟原虫寄生虫血症与血浆 HBV DNA 水平呈负相关（r = -0.6；P = 0.0003）。
HBV 感染可降低本流行地区个体的疟疾感染强度。这种作用似乎与细胞因子平衡和炎症反应的控制有关。这些发现为理解影响流行地区疟疾临床结局的因素提供了重要的见解。
