A retrospective survey of dengue virus infection in fatal cases from an epidemic in Brazil

Dengue virus can infect many cell types from the vascular, muscular and hematological systems causing diverse clinical and pathological signs. The purpose of the present study was to investigate by different diagnostic methods dengue virus in human tissue specimens obtained from fatal cases (n = 29) during a large-scale dengue fever epidemic in 2002 in the State of Rio de Janeiro, Brazil. The combination of four procedures provided diagnostic confirmation of DENV-3 infection in 26 (89.6%) out of the 29 suspected fatal cases. Dengue virus (DENV) was isolated from 2/74 (2.7%) tissue samples, inoculated into C6/36 cells and identified as DENV-3, nested RT-PCR accusing 22/72 (30.5%) samples as DENV-3. Real-time RT-PCR yielded the highest positivity rate, detecting viral RNA in 45/77 (58.4%) clinical specimens, including the liver (n = 18), lung (n = 8), spleen (n = 8), brain (n = 6), kidney (n = 3), bone marrow (n = 1) and heart (n = 1). Immunohistochemical tests recognized the DENV antigen in 26/59 (44%) specimens. Given the accuracy and effectiveness of real-time RT-PCR in this investigation, this approach may play an important role for rapid diagnosis of dengue infections.