Abstract: In April 2015, an outbreak of dengue-like illness occurred in Tuparetama, a small city in the northeast region of Brazil; this outbreak was characterized by its fast expansion. An investigation was initiated to identify the viral etiologies and advise the health authorities on implementing control measures to contain the outbreak. This is the first report of this outbreak in the northeast, even though a few cases were documented earlier in a neighboring city.
Plasma samples were obtained from 77 suspected dengue patients attending the main hospital in the city. Laboratory assays, such as real-time reverse transcription polymerase chain reaction, virus cDNA sequencing, and enzyme-linked immunosorbent assay, were employed to identify the infecting virus and molecular phylogenetic analysis was performed to define the circulating viral genotypes.
RNA of Zika virus (ZIKV) and Dengue virus (DENV) or IgM antibodies (Abs) to DENV or chikungunya (CHIKV) were detected in 40 of the 77 plasma samples (51.9%). DENV was found in 9 patients (11.7%), ZIKV was found in 31 patients (40.2%), CHIKV in 1 patient (1.3%), and coinfection of DENV and ZIKV was detected in 2 patients (2.6%). The phylogenetic analysis of 2 available partial DENV and 14 ZIKV sequences revealed the identities of genotype 1 and the Asiatic lineage, respectively.
Consistent with recent reports from the same region, our results showed that the ongoing outbreak is caused by ZIKV, DENV, and CHIKV. This emphasizes the need for a routine and differential diagnosis of arboviruses in patients with dengue-like illness. Coordinated efforts are necessary to contain the outbreak. Continued surveillance will be important to assess the effectiveness of current and future prevention strategies.
From the Clinical Laboratory, Department of Pathology (RP, SSS), Hospital das Clínicas (HC), School of Medicine, University of São Paulo, São Paulo; Municipal Hospital of Tuparetama (JVP, MDLDS, ACF, NM), Pernambuco; and Department of Virology (SSS), São Paulo Institute of Tropical Medicine, São Paulo, Brazil.
Correspondence: Sabri S. Sanabani, PhD, Universidade de São Paulo, Faculdade de Medicina, Instituto de Medicina Tropical de São Paulo, LIM 52 - Av. Dr. Enéas Carvalho de Aguiar, 470–2nd andar - Cerqueira Cesar, 05403-000 - Sao Paulo, SP - Brasil (e-mail: firstname.lastname@example.org;http://www.imt.usp.br).
Abbreviations: aLRT = approximate likelihood ratio test, BMH = Brazil ministry of health, bp = base-pair, CHIKV = Chikungunya virus, Cq = quantification cycle, DENV = Dengue vírus, ELISA = enzyme-linked immunosorbent assay, JEV = Japanese encephalitis virus, ML = maximum likelihood, ORF = open reading frame, qRT-PCR = quantitative reverse transcription polymerase chain reaction, RT-PCR = reverse transcription polymerase chain reaction, SLEV = St. Louis encephalitis virus, WNV = West Nile virus, YFV = yellow fever virus, ZIKV = Zika vírus.
Authors’ contributions: SSS conceived and designed the experiments; RP, ACF, and SSS performed the experiments; RP and SSS analyzed the data; NM contributed reagents/materials/analysis tools; JVP and MLS were the attending physicians for sample collection; SSS wrote the manuscript.
This work was partially supported by grants 2014/24596-2 from the Fundação de Amparo à Pesquisa do Estado de São Paulo.
The authors have no funding and conflicts of interest to disclose.
This is an open access article distributed under the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. http://creativecommons.org/licenses/by/4.0
Received December 7, 2015
Received in revised form February 23, 2016
Accepted March 4, 2016