Amidst the escalating dengue crisis in Brazil, the nation finds itself ensnared in a dire public health predicament. With over a million Brazilians falling victim to this viral scourge in 2024 alone, hospitals are being inundated, stretched to their limits.
The convergence of climatic upheavals, characterized by hotter and wetter conditions fueled by the climate crisis, alongside the resurgence of previously dormant subtypes of the dengue virus, has precipitated an unprecedented explosion of cases. Since January alone, Brazil has grappled with a staggering 1.6 million probable cases of dengue—a figure mirroring the entirety of last year’s reported cases—coupled with a grim toll of 491 confirmed deaths, with an additional 889 deaths under investigation as of March 14th.
You can also read: WHO Spearheads Change in Women’s Healthcare: Saima Wazed
This calamity emerges from the convergence of two critical factors. The current year has seen a proliferation of wet, balmy conditions, fostering the proliferation of Aedesaegypti mosquitoes—the very vectors responsible for dengue transmission. Compounding this challenge is the simultaneous circulation of all four strains of the dengue virus, leaving few individuals with comprehensive immunity.
Dengue Crisis in Brazil (2024):
- Over a million cases reported in 2024.
- Hospitals overwhelmed by the surge in cases.
- 491 confirmed deaths, with 889 deaths under investigation.
Factors Contributing to Dengue Outbreak:
- Climatic upheavals: Hotter and wetter conditions.
- Resurgence of previously dormant subtypes of the dengue virus.
All four strains of the dengue virus in circulation.
Wolbachia Bacterium Turns Tide against Dengue
In the battle against dengue, Brazil has marshaled its resources. Among its arsenal is a bold anti-dengue initiative aimed at thwarting the mosquito’s capacity to propagate disease by inoculating them with a common bacterium—Wolbachia. This bacterium fortifies the mosquitoes’ immune defenses, impeding the proliferation of dengue and other viruses within their bodies. Moreover, it competes with viruses for vital resources necessary for replication.
Championing this cause is the World Mosquito Program, which breeds and releases Wolbachia-infected mosquitoes into communities. These mosquitoes intermingle with their wild counterparts, resulting in offspring that carry the bacteria. Over time, Wolbachia proliferates throughout the mosquito population, effectively rendering them incapable of transmitting disease to humans.
Having witnessed firsthand the program’s endeavors in Medellín, Colombia—a bustling hub teeming with Wolbachia-infected mosquitoes— we recall the resounding words of Bryan Callahan, then director of public affairs, who likened the endeavor to vaccinating mosquitoes against human affliction.
The World Mosquito Program’s efforts took root in Brazil in 2014, spanning an expanse inhabited by over 3 million residents across five municipalities. Notably, in Niterói, a coastal community adjacent to Rio de Janeiro, preliminary releases of Wolbachia-infected mosquitoes commenced in 2015, evolving into larger-scale deployments by 2017. By 2020, the bacteria had permeated the local mosquito populace, yielding promising results. Dengue cases plummeted by a remarkable 69%, while incidences of chikungunya and Zika saw significant reductions.
The Wolbachia method has extended protection to a staggering 3.2 million individuals. An ambitious expansion, funded to the tune of 80 million reais, is set to encompass six additional municipalities, shielding an additional 1.7 million people from the scourge of dengue.
Wolbachia Initiative:
The Heart of Innovation
- Location: Rio de Janeiro laboratory within Fiocruz institute.
- Collaboration: Fiocruz, World Mosquito Program (WMP), and health ministry.
- Leadership: Supervised by biologist Cátia Cabral.
- Milestone: Housing millions of Wolbachia-infected mosquitoes.
- Expansion of Wolbachia initiative in Brazil, starting in 2014.
- Success in Niterói: Significant reduction in dengue cases (69%) and other arboviruses.
- Protection extended to 3.2 million individuals.
- Expansion plans to encompass six additional municipalities, shielding 1.7 million people.
- Funding: 80 million reais.
Niterói Leads the Charge
At the heart of this revolutionary initiative lies a Rio de Janeiro laboratory, nestled within a public health institute overseen by Fiocruz, in collaboration with the World Mosquito Program (WMP) and bolstered by support from the health ministry. Led by the dedicated supervision of Cátia Cabral, a seasoned biologist, the facility epitomizes the evolution from humble beginnings to a sprawling enterprise, housing millions of Wolbachia-infected mosquitoes. These remarkable creatures, affectionately dubbed ‘wolbitos’ by Brazilians, are meticulously bred and monitored by a dedicated team of 17 individuals, ensuring the continuity of the Wolbachia method’s implementation.
As the nation grapples with the current surge, early indicators from Niterói offer a glimmer of hope. The incidence of dengue remains notably low, with 69 confirmed cases per 100,000 individuals, in stark contrast to Rio de Janeiro’s staggering tally of over 42,000 cases, translating to an incidence of 700 per 100,000.
In the heart of Brazil, Niterói stands as a testament to triumph in the war against dengue. “Niterói is the first Brazilian city we have fully protected with our Wolbachia method,” declares Alex Jackson, global editorial and media relations manager for the World Mosquito Program. “The whole city is covered by Wolbachia mosquitoes, which is why the dengue cases are dropping significantly.”
However, this victory is just the beginning. The program’s ambitions extend far beyond Niterói’s borders, with plans to release Wolbachia mosquitoes in six more cities this summer alone. Yet, the vastness of Brazil’s terrain presents a daunting challenge; with over 5,000 municipalities, the program must release millions more mosquitoes to make a substantial impact nationwide.
Undeterred, the World Mosquito Program is poised for an unprecedented leap forward. Construction is set to commence on a monumental mass rearing facility in Curitiba—the largest of its kind globally. “And we believe that will allow us to essentially cover most of urban Brazil within the next 10 years,” asserts Callahan, radiating confidence in the program’s vision.
Multi-Pronged Defense Strategies Unveiled
Beyond Wolbachia, other innovative approaches are emerging. Oxitec, a UK company, has introduced genetically modified “friendly” mosquito eggs in Indaiatuba since 2018, while Forrest BrasilTecnologia has deployed sterile male mosquitoes in parts of Ortigueira, yielding a staggering 98.7% decline in Aedesaegypti population.
Moreover, Brazil is fortifying its defenses through vaccination campaigns and research on a home-grown dengue vaccine, recognizing the imperative of bolstering immunity against this relentless foe.
Diverse Approaches
- Oxitec: Introduces genetically modified “friendly” mosquito eggs.
- Forrest Brasil Tecnologia: Deploys sterile male mosquitoes, resulting in a 98.7% decline in Aedes aegypti population.
- Vaccination Campaigns: Brazil initiates nationwide vaccination efforts.
- Home-Grown Dengue Vaccine: Research underway for a locally developed vaccine.
Yet, amidst these strides, the specter of dengue looms large, exacerbated by the specter of climate change driving infections to new heights and uncharted territories. “Cases of dengue fever are rising at an alarming rate,” warns Gabriela Paz-Bailey of the US Centers for Disease Control and Prevention, underscoring the urgency of the situation.
In stark contrast to its neighboring metropolis, Niterói boasts a mere 689 probable dengue cases as of March 14th, a fraction of the staggering 61,779 cases recorded in Rio de Janeiro. Mayor Axel Grael attributes this remarkable discrepancy to the decisive implementation of the Wolbachia strategy, underscoring its pivotal role in safeguarding the city’s residents.
The allure of the Wolbachia method lies not only in its proven efficacy but also in its cost-effectiveness and self-sustaining nature, resonating strongly with city authorities. Luciano Moreira, a Fiocruz researcher at the helm of the World Mosquito Program (WMP) in Brazil, underscores the overwhelming demand for ‘wolbitos’ among municipalities, highlighting the method’s broad appeal.
However, as demand surges, the challenge lies in ramping up production to meet the burgeoning need. With the impending completion of a state-of-the-art mosquito-breeding lab by 2025, production capacity is set to skyrocket tenfold, poised to churn out a staggering 100 million eggs weekly.
