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A recent study conducted by Brazilian researchers has unveiled a concerning correlation between prior Zika infection and an increased risk of severe dengue and hospitalization. Published in the journal PLOS Neglected Tropical Diseases, the analysis showed that individuals with a history of Zika infection faced a 2.34 times higher risk of developing severe dengue and a 3.39 times higher risk of hospitalization compared to controls without dengue or Zika history.
Cassia Fernanda Estofolete, an infectious disease specialist at the Sao Jose do Rio Preto Medical School (FAMERP), highlighted the findings, stating that the research confirmed similar results observed in children with Zika in Nicaragua. The study shed light on the heightened risk of severe dengue following prior Zika infection, affecting adults in Brazil.
The study also addressed the non-classical nature of antibody-dependent enhancement (ADE), where antibodies, instead of providing protection, enhance viral entry into host cells, potentially exacerbating the disease. This mechanism differs from consecutive dengue virus infections and involves the activation of T cells, a crucial part of the immune system, leading to an excessive release of inflammatory cytokines.
With both dengue and Zika being flaviviruses transmitted by the same mosquito species (Aedes aegypti) and exhibiting similar symptoms, diagnosis can be challenging. Dengue, however, poses a greater threat as it can lead to severe complications such as bleeding and death. Zika, while often presenting milder symptoms, can cause severe issues in pregnant women and babies, including microcephaly and Guillain-Barre syndrome.
Estofolete emphasized the implications of the findings on vaccine development and administration, raising questions about the optimal timing and type of Zika vaccine to be used, especially in conjunction with a dengue vaccine. Understanding the mechanism detected in the study is crucial for addressing severity across all dengue serotypes and advancing knowledge on Zika vaccines.
The study, which analyzed samples from over a thousand laboratory-confirmed dengue patients, underscores the need for further research to unravel the complexities of interactions between flaviviruses and immune responses. Beyond elucidating severity factors, the goal is to inform vaccine strategies and mitigate the impact of these mosquito-borne diseases on public health.
