Vírus Zika no Estado do Rio Grande do Norte: aspectos epidemiológicos e filogenéticos

Abstract

Rio Grande do Norte (RN) was one of the first states where the virus was initially detected in Brazil, probably due to the tourists flow, the high degree of Aedes aegypti infestation and the precariousness of environmental sanitation.The presence of this arbovirus in RN, the notification of severe cases, the scarcity of available works on this subject and its possible introduction of the virus in Brazil during the Confederations Cup 2013, served as motivation for the accomplishment of this study that sought to investigate the circulation of the Zika virus in the State of Rio Grande do Norte and to perform the molecular characterization of the isolated viruses during the period from June 2013 to December 2016. In this period, patient samples were analyzed using the reverse transcription technique followed by real-time polymerase chain reaction (qRTPCR) for the detection of the viral genome. ZIKV infection was confirmed in 8.97% (73/814) of the cases studied. The analysis of the spatial distribution of the virus by the different micro regions of the State showed its circulation in 16 municipalities. The municipalities with the highest number of confirmed cases were Natal and Parnamirim. The period with the highest incidence of infection occurred in the months of March, April and May of 2015 however, the highest proportions of positive cases occurred in the months of November and December of 2014 and February of 2015. The majority of cases of Zika infection occurred in female patients, but without significant difference in relation to males. Zika virus infection reached all age groups with practically the same infection incidence rates. No correlation between viremia estimation and disease time in patients was found, as well as, no significant differences in viremia according to the type of sample analyzed (serum/whole blood), but there was a significant difference in viremia between the fourth and fifth day of symptoms analyzed. Phylogenetic analysis indicated that the circulating ZIKV in the state belong to the Asian genotype.The amino acid comparison between ZIKV identified in this study and the ancestral strains isolated in Malaysia showed three mutations with amino acid changes: D393E, V473M and T487M. These mutations were found in domain III of the protein (E), and probably influence the pathogenicity of Zika virus strains circulating in Rio Grande do Norte. This study provides the necessary inputs to understand the distribution and dynamics of the disease in the State of Rio Grande do Norte and the genetic analyses are fundamental for understanding the biological aspects of the virus.