Detection of dengue virus in sera of Brazilian blood donors

BACKGROUND: Dengue is the most important arboviral disease in the world. Dengue viruses (DENVs) have produced huge outbreaks in Brazil in the past 25 years with more than 5 million reported cases. During these epidemics, asymptomatic individuals infected with DENV could donate blood and serve as a source of virus dissemination in the community. Here, we studied the circulation of DENV in healthy individuals during an epidemic outbreak. STUDY DESIGN AND METHODS: The study included 500 serum samples from healthy blood donors collected at the Hemotherapy Center of Ribeirao Preto, Brazil, during a dengue outbreak. The presence of DENV RNA in the serum samples was screened by real-time reverse transcriptionpolymerase chain reaction (PCR). The virus serotype was determined by a heminested PCR procedure. A partial fragment of the NS5 gene sequence was used for phylogenetic analysis. RESULTS: DENV RNA was detected in the serum sample of 2 of 500 (0.4%) individuals. Both of them were infected with DENV-3 Genotype III, a virus that has been circulating in Brazil in the past decade. CONCLUSION: Individuals with asymptomatic DENV infection can be blood donors and serve as a source of virus dissemination in the community. Further studies are needed to determine the risk of recipient infection by DENV as a result of transfusion in Brazil, especially during epidemic periods.

First Identification of Culex flavivirus (Flaviviridae) in Brazil

Introduction: Culex flavivirus (CxFV) was first isolated in 2007 from Culex pipiens in Japan and then identified in several other countries. Characterization of the CxFV showed that all strains are related to the cell fusing agent virus. In this manuscript we report the first identification of CxFV in South America. Material and Methods: We have collected Culex sp. mosquitoes using BG-Sentinel traps and manual aspirators. They were pooled according to genus, species, sex and location. Viral RNA was extracted and multiplex nested PCR was performed to test the presence of Flavivirus. The positive samples were isolated in C6/36 cells and sequenced for phylogenetic analyses. Results: 265 female Culex mosquitoes pooled in 83 pools were tested with specific CxFV, Saint Louis encephalitis virus (SLEV) and West Nile virus (WNV) primers. Our sequence data indicated maximum sequence similarity of 97% with CxFV. Discussion: In this study we report the circulation of CxFV in an urban setting where SLEV had previously caused an outbreak. In terms of public health, this is an important finding due to the assumption that the previous exposition of mosquitoes to CxFV might lessen the susceptibility of these mosquitoes to other flaviviruses. Copyright (C) 2012 S. Karger AG, Basel