A recent study has discovered a startling correlation between prior Zika virus infection and subsequent severe dengue and hospitalization. The study suggests that individuals who have previously contracted the Zika virus are at an elevated risk for severe dengue if they are later infected with the dengue virus. This revelation underscores the potential long-term health implications of Zika infection and highlights the need for vigilant monitoring and management of individuals with a history of Zika infection.
The Brazilian Study
In a study led by Brazilian researchers, it was found that those who have had the Zika virus run a higher risk of subsequently experiencing severe dengue and requiring hospitalization. This study reveals that the viral load is higher in the second dengue episode with high levels of inflammatory cytokines, a phenomenon not seen in Zika. Interestingly, a prior dengue infection was not identified as a risk factor for severity, but a previous Zika infection was indeed an aggravating factor.
Brazil has seen a significant increase in dengue cases, with the number of cases in November 2023 surpassing the total number reported in the whole of 2022. There were 1,372,000 confirmed cases and 4,773 probable cases of Zika, highlighting the urgency of this issue.
The Risk of Hospitalization
Research has indicated that individuals who have previously been infected with the Zika virus are at a higher risk of developing severe dengue fever and requiring hospitalization. Individuals with a prior Zika infection were significantly more likely to experience severe dengue symptoms compared to those without a history of Zika. Furthermore, the risk of hospitalization due to dengue fever was also higher in individuals with a previous Zika infection. The findings emphasize the need for continued research and public health efforts to combat these mosquito-borne diseases effectively.
Understanding Dengue Infections
A study on the spatial and temporal trends of dengue infections in Curaçao over a 21-year period highlighted the importance of understanding these patterns for effective prevention and control of future outbreaks. The study found a relationship between population density and dengue cases, as well as a correlation between lower temperatures, higher precipitation, and lower sea surface temperatures with an increase in dengue cases. The analysis also noted the impact of La Niña episodes on dengue outbreaks.
Vaccination and Prevention
A phase 3 trial of the single-dose tetravalent Butantan-Dengue Vaccine (Butantan D-V) showed 80% protection among participants with no evidence of previous dengue exposure and 89% protection in those with a history of exposure. The vaccine is the result of years of research from Brazil’s Butantan Institute, with the study including results from 16 Brazilian centers located in all five regions of the country.
Each year at least 1 million Brazilians get infected with dengue; the current incidence rate in the country is calculated as 107.1 cases per 100,000 inhabitants, and the fatality rate is 0.9%. The trial began in February of 2016 and included 16,235 participants in Brazil; roughly 10,000 were vaccinated with the one-dose vaccine, and about 6,000 received a placebo. Among the 270 study participants who developed a dengue infection during the study, all had mild to moderate cases of illness, and none were hospitalized.
The introduction of the Zika virus to Brazil in 2015 has altered natural infections of dengue, with a Zika infection acting as a priming dengue infection in the immune system, and eliminating circulation of serotypes 3 and 4 since 2016. Given the realities of the dimensions of the dengue pandemic in the 20th and 21st centuries, a highly effective, one-dose, tetravalent vaccine remains in high demand. Butantan-DV clinical trials should continue and, if possible, be expanded.
The findings from these studies stress the importance of public health initiatives and continued research into effective vaccinations. Individuals with previous Zika infections need to be monitored and managed carefully to prevent severe dengue episodes and hospitalization. The link between prior Zika infection and severe dengue underscores the complex relationship between these two mosquito-borne diseases and the need for a comprehensive approach to their prevention and treatment.