Prior Zika Exposure Increases Risk of Severe Dengue, Study Finds

Researchers from Sao Paulo Research Foundation (FAPESP) found that the mechanism exacerbating dengue severity following Zika infection differs from that of two consecutive dengue infections, involving higher viral loads and activation of T cells leading to excessive inflammation.

  • Individuals previously infected with Zika faced a 2.34 times higher risk of severe dengue and a 3.39 times higher likelihood of hospitalization, highlighting a link between prior Zika exposure and increased dengue severity.
  • The study uncovered non-classical antibody-dependent enhancement (ADE) mechanisms, suggesting a more complex relationship between Zika and dengue infections than previously understood.

A recent study published in PLOS Neglected Tropical Diseases reveals that individuals with a history of Zika infection face a significantly elevated risk of experiencing severe dengue and requiring hospitalization. Researchers found that those with prior Zika exposure had a 2.34 times increased risk of severe dengue and a 3.39 times higher likelihood of hospitalization compared to controls without a history of dengue or Zika. This highlights a concerning link between Zika and dengue infections, particularly in regions where both diseases are prevalent.

The study, led by infectious disease specialist Cassia Fernanda Estofolete from the Sao Jose do Rio Preto Medical School (FAMERP), sheds light on the underlying mechanisms contributing to the increased severity of dengue following Zika infection. The research team identified non-classical antibody-dependent enhancement (ADE) mechanisms, where antibodies enhance viral entry into host cells, exacerbating the disease. Additionally, the study uncovered differences in the viral load and inflammatory response between Zika-induced and consecutive dengue infections, suggesting distinct pathways leading to severe dengue.

These findings raise important questions about the development and administration of vaccines targeting Zika and dengue. Researchers emphasize the need to explore whether the mechanisms identified in the study apply to all dengue serotypes, which could influence vaccine strategies. With both Zika and dengue being flaviviruses transmitted by the same mosquito species, understanding their interaction and mitigating the risk of severe outcomes is crucial for effective disease management and vaccine development efforts.