Abstract
The Asian/American genotype of dengue virus serotype 2 (DENV-2) has been introduced in Brazil through the state of Rio de Janeiro around 1990, and since then it has been spreading and evolving, leading to several waves of dengue epidemics that cause a major public health problem. Of particular interest has been the epidemic of 2008, whose highest impact was evidenced in the state of Rio de Janeiro, with a higher number of severe cases and mortality rate, compared to previous outbreaks. Interestingly, no circulation of DENV-2 was witnessed in this region during the preceding 9-year period. By that time, a new viral lineage of the Asian/American genotype was identified and pointed as responsible for the outbreak severity. The same scenario is repeating in 2019 in this state, however, only a few cases have been detected yet. With the aim to avoid an outbreak a great magnitude we employed phylogenetic studies combined with temporal and geographical features to determine the origin of the current viral strain, analyzing a region of 1626 nucleotides entailing the Envelope/NS1 viral genes. Our study reveals that the current strain belongs to the same lineage that caused the 2008 outbreak, however, it is phylogenetically distant from any Brazilian strain identified so far. Indeed, it seemed to be originated in Puerto Rico around 2002 and has been introduced into the state in late 2018. Taking into account that no DENV-2 case was reported over the last decade in the state, which represents a whole susceptible children generation, and the fact that a new viral strain may be causing current dengue infections, these results would be essential to strengthen dengue surveillance and disease control, avoiding the potential epidemiological consequences of virus spread.
Author Summary By the time DENV2 was introduced into Brazil through the state of Rio de Janeiro in 1990, the first dengue haemorragic cases started to evidence as well. Years of seasonal outbreaks were followed by almost ten years oy epidemiological silence in the state. However, in 2007 this serotype was re-introduced into the state causing one of the worst dengue epidemics ever described in the country. The same viral genotype was involved, however, a different viral lineage was detected and pointed as responsible for the outbreak severity. This same scenario could repeat nowadays in the state of Rio de Janeiro. Since new DENV-2 cases are being detected in this region, we analyzed the identity and origin of the viral strain obtained from two infected patients. Phylogeny combined with temporal and geographical analyses of viral sequences demonstrated that the strain causing 2019′s dengue cases belonged to the same lineage as the one causing the outbreak in 2008, but to a different subgroup, and might have originated in Puerto Rico and entered the state in recent times. This results may help to prevent the recurrence of epidemics of great magnitude and may represent as well a key starting point to strengthen Brazilian surveillance systems and disease control.
Footnotes
Competing Financial Interests Statement: The authors declare no competing financial interests.