In a significant development in the realm of tropical diseases, a recent study led by Brazilian researchers has unveiled a crucial link between Zika virus and severe dengue. This research has brought to light that individuals with a history of Zika infection are at a higher risk of developing severe dengue and requiring hospitalization. The findings, published in the journal PLOS Neglected Tropical Diseases, have important implications for the development of a Zika vaccine and the management of both diseases.
The Study and its Findings
The researchers conducted an in-depth analysis of samples from 1,043 laboratory-confirmed dengue patients in São José do Rio Preto, Brazil. They found that a prior Zika infection acts as an aggravating factor in a second dengue episode, leading to an increase in the severity and viral load. This discovery is renewing our understanding of these diseases and presenting novel insights into their mechanisms.
Using an enzyme-linked immunosorbent assay (ELISA), the researchers evaluated the past history of dengue and Zika infection among the patients. The results suggested that patients with a history of Zika infection were significantly more likely to develop severe dengue and require hospitalization.
The Impact on Zika and Dengue Management
These findings are particularly important considering the increasing number of dengue cases in Brazil. In November 2023, the number of dengue cases surpassed the total number reported in the entire year of 2022, reaching 1,372,000 cases.
Understanding the correlation between Zika and dengue viruses is crucial for preventing and managing outbreaks of both diseases. A prior Zika infection seems to act as a priming dengue infection in the immune system, altering the natural infection patterns of dengue and raising questions about the type and timing of Zika vaccination.
Implications for Vaccine Development
The non-classical nature of antibody-dependent enhancement (ADE) highlighted by the study raises crucial questions about the type of Zika vaccine that should be used and the optimal timing of its administration. The lead researcher of the study, Cássia Fernanda Estofolete, emphasized the need to understand the mechanisms of severity for all dengue serotypes and the lack of accumulated knowledge about Zika vaccines.
While a dengue vaccine produced by a Japanese company has won approval from ANVISA, Brazil’s health surveillance agency, and is now available from private clinics, the development of a Zika vaccine is still at an earlier stage. The Brazilian Butantan Institute is also developing an entirely indigenous dengue vaccine for distribution to public clinics.
The Way Forward
This groundbreaking research underscores the importance of understanding the interaction between Zika and dengue viruses to develop effective vaccines and control strategies. As the number of dengue cases continues to rise, this understanding is crucial for mitigating the risk of severe dengue following a Zika infection.
Public health initiatives and continued research into effective vaccinations are vital. The findings of this study present a crucial stepping stone towards better managing and controlling the outbreaks of these diseases and developing a Zika vaccine that takes into account the risk of severe dengue.