Laboratory surveillance of dengue in Rio Grande do Sul, Brazil, from 2007 to 2013.

Gabriela Luchiari Tumioto,Ana Beatriz Gorini Veiga,Tatiana Schäffer Gregianini,Zenaida Marion Alves Nunes,Beatriz Carneiro Cestari,Bibiana Paula Dambros,Ray Borrow

doi:10.1371/journal.pone.0104394

Abstract

BackgroundAccording to official records, dengue was introduced in Brazil in the 80's; since then several epidemics have occurred. Meanwhile, in Rio Grande do Sul (RS, Southern Brazil) the first autochthonous case occurred only in 2007.Methodology and Principal FindingsIn this study we report laboratory surveillance of dengue cases and seasonality of positive cases, describe serotypes and characterize the epidemiological pattern of dengue in RS from 2007 to 2013. A total of 9,779 serum samples from patients with suspected dengue fever were collected and submitted to molecular and/or serological analyses for dengue virus identification and serotyping, based on viral isolation, NS1 antigen detection and qRT-PCR, or Dengue IgM capture ELISA and MAC-ELISA. The first autochthonous dengue case in RS was confirmed in 2007 (DENV-3). While in 2008 and 2009 only imported cases were registered, autochthonous infection waves have been occurring since 2010. The highest number of dengue infections occurred in 2010, with DENV-1 and DENV-2 outbreaks in Northwestern RS. In 2011, another DENV-1 and DENV-2 outbreak occurred in the Northwestern region; moreover, DENV-4 was detected in travelers. In 2012, DENV-1 and DENV-4 co-circulated. DENV-2 circulation was only detected again in 2013, in high frequency (56.7%), co-circulating with DENV-4 (35%). Most infections occur in adults during summer. Differences in prevalence between genders were observed in 2007 (60% females), 2008 (60.8% males) and 2009 (77.5% males).ConclusionsAccording to results of dengue surveillance, there was an increase in the number of dengue cases in RS and of cities infested with Aedes aegypti, possibly as a consequence of introduction of new serotypes and the difficulty of health programs to control the vector.

Highlights

Dengue fever (DF) is the most important arthropod-borne viral disease and is considered a serious public health problem [1], affecting between 50-100 million people/year worldwide, causing 250,000 cases of Dengue Hemorrhagic Fever (DHF)
According to results of dengue surveillance, there was an increase in the number of dengue cases in Rio Grande do Sul (RS) and of cities infested with Aedes aegypti, possibly as a consequence of introduction of new serotypes and the difficulty of health programs to control the vector
The first laboratory-confirmed dengue virus (DENV) case was reported in the State of Roraima (Northern Brazil) only in 1981–1982, with the introduction of DENV-1 and DENV-4, probably an extension of the DENV epidemics waves that had occurred in Central America and in northern parts of South America [1]

Summary

Introduction

Dengue fever (DF) is the most important arthropod-borne viral disease and is considered a serious public health problem [1], affecting between 50-100 million people/year worldwide, causing 250,000 cases of Dengue Hemorrhagic Fever (DHF). All four serotypes can be distinguished by serological and molecular methods [5], [6]. In Brazil, there are reports of dengue epidemics in 1916 and 1923, in the States of Sao Paulo and Rio de Janeiro (Southeast Brazil), respectively. The first laboratory-confirmed DENV case was reported in the State of Roraima (Northern Brazil) only in 1981–1982, with the introduction of DENV-1 and DENV-4, probably an extension of the DENV epidemics waves that had occurred in Central America and in northern parts of South America [1]. In Rio Grande do Sul (RS, Southern Brazil) the first autochthonous case occurred only in 2007

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Conclusion