Dengue in Rio Grande do Sul, Brazil: 2014 to 2016

The first autochthonous dengue case in Rio Grande do Sul (RS), Southern Brazil, occurred in 2007. In 2008 and 2009, only imported cases were reported in RS, but from 2010 to 2013, reports of autochthonous infections increased significantly. This study analyzes and discusses laboratory, demographic, and clinical data regarding dengue cases in RS, from 2014 to 2016. This study analyzed 13,420 serum samples from notified patients with suspicion of dengue fever in RS from 2014 to 2016. Seasonality of positive cases, viral serotypes, and clinical and epidemiological aspects were analyzed. There was no difference in gender (P = .4); dengue fever occurred mainly in adults, with similar distribution among age groups. The number of dengue virus (DENV) cases increased from 89 cases in 2014 to 2518 in 2016. Dengue virus 1 was the most prevalent circulating serotype during this period (97.5% of cases). Dengue virus infections show peaks in March and April (late summer and early autumn), after periods of high temperatures and rainfall. In 2014, dengue cases were concentrated in the northwestern and eastern regions of RS, and in 2015 and 2016, the northern region also confirmed a high number of cases. With increase in DENV circulation in RS, a rise in the number of autochthonous infections was also observed, mainly in highly urbanized areas. This study revealed that circulation of DENV in RS increased significantly in 2015 and 2016, with a rise in the number of autochthonous infections and cocirculation with Chikungunya and Zika viruses, recently introduced into RS.