First report of autochthonous transmission of Zika virus in Brazil

Abstract

In the early 2015, several cases of patients presenting symptoms of mild fever, rash, conjunctivitis and arthralgia were reported in the northeastern Brazil. Although all patients lived in a dengue endemic area, molecular and serological diagnosis for dengue resulted negative. Chikungunya virus infection was also discarded. Subsequently, Zika virus (ZIKV) was detected by reverse transcription-polymerase chain reaction from the sera of eight patients and the result was confirmed by DNA sequencing. Phylogenetic analysis suggests that the ZIKV identified belongs to the Asian clade. This is the first report of ZIKV infection in Brazil.

Fig. 1. : agarose gel electrophoresis of reverse transcription-polymerase chain reaction assays for Zika virus (ZIKV) detection. The arrow indicates the 364 bp amplicon expected for ZIKV. RNA extracted from serum samples of patients in acute-phase of dengue fever and Chikungunya fever and a negative serum sample were included as negative controls. CHIKV: Chikungunya virus; M: molecular size marker; 1-21: serum samples.

Fig. 2. : phylogenetic analysis based on partial E gene nucleic acid sequence (nt 1655-1984 according to AY632535) of a 2015 Brazilian strain of Zika virus. The tree was inferred using the maximum likelihood algorithm based on the Kimura two-parameter model with invariant sites as implemented in MEGA 6.05. The numbers shown to the left of the nodes represent bootstrap support values > 70 (1,000 replicates). The tree was rooted with Spondoweni virus and branch lengths do not represent genetic distance. Strains were labelled according to GenBank accession /country 2-letter acronym/year of isolation.

Fig. 3. : Zika virus clinical findings in patients from Natal, state of Rio Grande do Norte, Brazil. A: lymphadenopathy; B: maculopapular rash; C: periarticular swelling.