Explosive Rise in Dengue Cases in Brazil Sparks Concerns and Vaccination Campaign
Brazil is currently facing a major health crisis as the country experiences an explosive rise in dengue cases. In just the first two months of 2024, over one million cases of the mosquito-borne disease have been registered, setting a record for this period. Typically, dengue cases in Brazil peak between March and May, making this early surge even more concerning.
The surge in dengue cases can be attributed to various factors, including climate change and rapid urban growth. Rising temperatures associated with climate change have allowed the disease to spread into regions of Brazil that were once too cold for the Aedes aegypti mosquito, which transmits the virus. Additionally, an El Niño event that arrived in mid-2023 has intensified the heat and rainfall, further contributing to the surge.
However, climate is not the sole factor responsible for the increase in dengue cases. The rapid growth of Brazilian cities has created ideal breeding grounds for mosquitoes. Inadequate sanitation infrastructure, coupled with uncollected rubbish and stagnant water, provides the perfect environment for mosquitoes to thrive. Even adverse conditions such as puddles and sewers are now suitable breeding sites for Aedes aegypti mosquitoes.
Furthermore, limited natural immunity among the population has also contributed to the surge. Dengue is caused by four distinct viral subtypes, and after several years of predominance by the first two subtypes, the last two have recently returned. Many Brazilians are vulnerable to these subtypes, making them more susceptible to infection.
In response to the crisis, Brazil has launched a public vaccination campaign against dengue, becoming the first country to do so. The vaccine being administered is called Qdenga, manufactured by Takeda in Osaka, Japan. It has shown an overall efficacy of 73% against symptomatic dengue, with more promising results against certain subtypes. However, the distribution of the vaccine is currently limited to only 521 cities, less than 10% of Brazil’s municipalities.
Experts warn that the vaccination campaign is too modest to effectively address the immediate crisis. Mass vaccination is necessary to have a significant impact on the rates of dengue. Additionally, basic sanitation problems must be addressed to truly combat the disease. Vaccination alone will not be enough if proper housing conditions, access to clean water, and waste collection are not improved.
While the current vaccine may not fully resolve the problem, there is hope for another vaccine being developed by the Butantan Institute in São Paulo. In a large clinical trial, this vaccine demonstrated an overall efficacy of 80% against symptomatic dengue with a single dose. However, its effectiveness against certain subtypes remains unclear.
In addition to vaccines, other technologies are being explored to prevent dengue. One such approach involves releasing modified mosquitoes carrying the Wolbachia bacterium, which reduces the insect’s capacity to transmit viruses. This method has already shown promising results in several cities in Brazil, leading to a decrease in dengue cases.
Looking ahead, solving basic sanitation problems remains crucial in overcoming dengue. Vaccines and other technologies can serve as important auxiliary tools, but without proper housing conditions and access to clean water, the burden of neglected diseases like dengue will persist in Brazil. Efforts are underway to address these issues and combat the current health crisis, but it will require a comprehensive approach involving various strategies and stakeholders.
As Brazil grapples with the alarming rise in dengue cases, it is clear that urgent action is needed to protect the population from this deadly disease. The vaccination campaign is a step in the right direction, but it must be expanded to reach more people. Simultaneously, efforts to improve sanitation infrastructure and implement mosquito control measures should be intensified. Only through a combination of these approaches can Brazil hope to overcome the dengue crisis and safeguard the health of its citizens.
