News Release

The protective role of dengue immunity on Zika infection in a Brazilian favela

Peer-Reviewed Publication

American Association for the Advancement of Science (AAAS)

By monitoring the spread of Zika virus through a densely populated Brazilian favela during a 2015 outbreak, researchers have gained new perspectives into the outbreaks of this virus in the Americas in recent years. The results highlight the protective effect of prior immunity to dengue virus. Because many Zika virus (ZIKV) infections are asymptomatic and non-specific in their clinical presentation, the infection dynamics of the virus have been difficult to characterize. One key unknown, the subject of numerous studies, is the role of pre-existing immunity to dengue virus (DENV), an endemic pathogen that shares many similarities to ZIKV. While DENV immunity has been hypothesized to influence both susceptibility to and resistance of ZIKV infection, neither trajectory has been rigorously evaluated in human populations. Leveraging a long-term health study in Salvador, Brazil -- the epicenter of a 2015 ZIKV outbreak -- Isabel Rodriguez-Barraquer and colleagues were able to characterize the transmission of the virus within an urban favela community. Rodriguez-Barraquer et al. used multiple serological assays, collected before and after the 2015 outbreak. They revealed that, of the 1,435 community residents tested, nearly 73% were infected by ZIKV during the epidemic. The presence of pre-existing DENV antibodies was associated with less risk of ZIKV infection and also of fewer experienced symptoms among those infected with ZIKV. Rodriguez-Barraquer et al. emphasize the highly spatial nature of ZIKV attack rates, which could indicate pockets of susceptible individuals that could sustain virus transmission after an apparent end to an epidemic. According to the authors, these groups may represent an opportunity for vaccine trials, to truly and effectively resolve the epidemic in populations that appear to have high immunity.

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