In a remarkable public health advancement, three densely populated Colombian cities experienced a dramatic decline in dengue cases following the release of Aedes aegypti mosquitoes infected with Wolbachia, a bacterium that inhibits the mosquitoes’ ability to transmit viruses. Conducted by the World Mosquito Program (WMP), this initiative, the largest of its kind, saw dengue incidences plummet by 94–97% in areas where these modified mosquitoes became prevalent.
The WMP, which has previously conducted similar projects globally, achieved substantial success in Colombia’s Aburrá Valley, covering Bello, Medellín, and Itagüí. This area, home to 3.3 million people, saw a significant reduction in dengue cases, with Bello and Medellín registering a 95% drop and Itagüí a 97% decrease compared to the ten-year period before the intervention. This success is attributed to the Wolbachia-infected mosquitoes, which are less likely to transmit diseases like dengue and Zika and can pass the bacterium to their offspring.
The project in Colombia faced challenges in measurement and evaluation, acknowledging the natural oscillations in dengue incidence. However, the promising results were presented by Katie Anders, an epidemiologist at WMP, at the annual meeting of the American Society of Tropical Medicine and Hygiene. While randomized controlled trials are the gold standard for evaluating such public health interventions, the results from similar trials in Indonesia and ongoing ones in Brazil are encouraging.
Despite these positive outcomes, the World Health Organization (WHO) has not officially endorsed Wolbachia mosquitoes yet. The WMP, undeterred, plans to scale up the project, with proposals to build a factory in Brazil for producing modified mosquitoes. This expansion will require tailoring strategies to each region’s geographical and social circumstances, highlighting the importance of local partnerships and community engagement in combating mosquito-borne diseases.