Acesso restrito: Texto completo. p. 1-9.Background: 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.
Methodology and Findings: An observational study of 636 individuals was performed in Rondoˆ nia, 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 =20.6; P = 0.0003).
Conclusion: 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
