Guilherme Ribeiro and colleagues (February, 2018) report a major downward trend in dengue virus infection cases after the recent Zika virus outbreak in the Americas. They used epidemiological data collected between 2009 and 2017 in Salvador, Brazil, to suggest that the decline in dengue virus infection cases observed since 2015 could be the result of cross-protective immunity to dengue virus induced by Zika virus infection.
(guilherme.ribeiro@bahia.fiocruz.br Instituto Gonçalo Moniz, Fundação Oswaldo Cruz, 40296-710 Salvador, Brazil.)