Dengue 4 in Ceará, Brazil: characterisation of epidemiological and laboratorial aspects and causes of death during the first epidemic in the state

BACKGROUND The first dengue cases in Brazil with laboratory confirmation occurred in the northern region of the country, with the isolation of two serotypes, dengue virus 1 (DENV-1) and DENV-4. In Ceará, the introduction of DENV-4 was reported during a DENV-1 epidemic in 2011, with only two isolations. OBJECTIVES The aim of this study was to characterise the first DENV-4 epidemic in the state of Ceará, Brazil. METHODS The study population was composed of patients with suspected dengue that were reported to health care units from January to December 2012. The laboratory confirmation of infection was made by viral isolation, reverse transcription polymerase chain reaction (RT-PCR), AgNS1, immunohistochemistry and IgM enzyme-linked immunosorbent assay (ELISA). MAIN CONCLUSIONS In the study year, 72,211 suspected dengue cases were reported and 51,865 of these cases (71.8%) were confirmed to be positive. Co-circulation of three serotypes, DENV-1, DENV-3 and DENV-4, was detected with a predominance of DENV-4 (95.3%). Most cases were not severe, but there were 44 fatal outcomes. DENV-4 Genotype II was identified for the first time in Ceará.