ZIKA PUZZLE IN BRAZIL: PECULIAR CONDITIONS OF VIRAL INTRODUCTION AND DISSEMINATION - A REVIEW
Cristina Possas1,+, Patricia Brasil2, Mauro C. A. Marzochi2, Amilcar Tanuri3, Reinaldo M. Martins1, Ernesto T. A. Marques4,5, Myrna C. Bonaldo6, Antonio G. P. Ferreira1, Ricardo Lourenço-de-Oliveira6, Rita Maria R. Nogueira6, Patricia C. Sequeira6, Keyla B. F. Marzochi2, Akira Homma1
1Bio-Manguinhos, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
2Evandro Chagas National Institute of Infectious Diseases, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
3Institute of Biology, Federal University of Rio de Janeiro, Brazil.
4Instituto Aggeu Magalhães, Oswaldo Cruz Foundation, Pernambuco, Brazil.
5University of Pittsburgh, United States.
6Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
This article discusses the peculiar conditions that have favored the unexpected Zika virus introduction in the poorest Northeast region of Brazil in 2015, its speed of transmission to other Brazilian states, other Latin American countries and other regions, and the severity of related neurological disorders in newborns and adults. Contrasting with evidences that Zika had so far caused only mild cases in humans in the last six decades, the epidemiological scenario of this outbreak in Brazil indicates dramatic health effects: in 2015, an increase of 20-fold in notified cases of microcephaly and/or central nervous system (CNS) alterations suggestive of Zika congenital infection followed by an exponential increase in 2016, with 2106 cumulative cases confirmed in the country by the end of October 2016. A significant increase in Guillain-Barré syndrome in adults has also been reported. Factors involved in viral dissemination, neural pathogenesis and routes of transmission in Brazil are examined, such as the role of social and environmental factors and the hypothesis of antibody-dependent enhancement, to explain the incidence of congenital Zika syndrome in Brazil. Responses to the Zika outbreak and the development of new products are also discussed.