Generales

By Carlos Olimpo Restrepo S., Journalist at UdeA Communications Office 

The growing number of diseases, such as dengue fever, has raised concerns in many countries, including Colombia. Still, this doesn’t reflect a lack of action. On the contrary, health authorities have intensified efforts to prevent outbreaks, detect cases early, and maintain control. National and international organizations are working closely to manage risks and respond swiftly to any epidemiological threats. 

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Tolima faces the country’s worst yellow fever outbreak in a decade. Photo: Tolima Health Secretariat 

In 2024, the Americas experienced a sharp increase in dengue cases, with 12.7 million reported—nearly triple the number from 2023, according to figures submitted to the Pan American Health Organization (PAHO). Colombia’s National Institute of Health (INS) also registered a significant increase, reporting 320,982 cases—three times more than the previous year. 

Along with the surge in dengue, Colombia has experienced a sharp increase in yellow fever cases. In 2024, the country reported 23 cases, resulting in 13 deaths. By May 2025, the number of cases had risen to 83, with most concentrated in Tolima. This sharp increase contrasts with the 2013–2023 period, during which the National Institute of Health (INS) recorded only 11 cases. 

Dengue spreads to humans primarily through the Aedes aegypti mosquito, while yellow fever is mainly transmitted by Haemagogus mosquitoes and, to a lesser extent, by Aedes mosquitoes. 

The growing threat of these diseases may lead some to believe that public health policies are not effective. A similar trend is appearing with other diseases, and national and international warnings about them are detailed at the end of this report. 

Researchers from the Universidad de Antioquia, together with officials from national and international organizations, emphasize that these epidemiological events generate timely alerts and prompt responses, all in line with protocols established by the World Health Organization (WHO) and other regional and national authorities. 

The national government declared a health emergency for yellow fever, and by Sunday, April 20, 542,363 people aged 9 months to 60 years had been vaccinated this year. These vaccinations come in addition to the over 1.1 million people vaccinated in 2024, according to the Ministry of Health. 

Dengue prevention campaigns continue nationwide, with coordinated efforts among national, regional, and local health authorities. In Medellín, Bello, and Itagüí, the release of Aedes aegypti mosquitoes infected with Wolbachia bacteria—resulting from a collaboration between the World Mosquito Program (WMP) and the University of Antioquia’s PECET—kept reported cases to just under 3,000, a remarkably low figure considering the population sizes of these cities. 

Dr. Carlos Alberto Rojas Arbeláez, PhD in epidemiology and professor at the National School of Public Health, UdeA, explained, “This is a normal pattern. Infectious diseases transmitted by vectors and insects follow cyclical trends, with cases rising periodically.” 

Likewise, Guillermo Rúa Uribe, leader of the Medical Entomology group at the University of Antioquia’s Faculty of Medicine, explained that diseases such as malaria and dengue respond strongly to climate changes, causing outbreaks to peak every three to five years. 

The Public Health Surveillance Protocol, released by Colombia’s National Institute of Health (INS) in July 2024, confirms that “a new epidemic phase of dengue began in 2023, mirroring trends seen in several countries across the Americas” and that this phase has persisted into the current year. 

Constant monitoring by health centers, hospitals, and government agencies at all levels allows for timely identification of disease outbreaks. These institutions regularly track and evaluate case numbers and types, sharing this information with international organizations. 

“Monitoring at different levels enables us to predict when disease cases will surpass certain limits. We issue alerts only at that moment—never before—because, while the public health system strives to anticipate outbreaks, it must exercise great caution when raising alarms,” explained Dr. Rojas Arbeláez. 

Dionisia Yusti Rivas, Undersecretary of Public Health for Antioquia’s Department of Health, emphasized that the agency maintains ongoing prevention efforts to control these diseases and intensifies educational and vaccination campaigns in response to national and international alerts. 

“We’re actively coordinating with municipalities on multiple campaigns. Our top priority is educating the public about preventing the spread of Aedes aegypti, the mosquito that transmits dengue and can also spread yellow fever. We urge people to remove stagnant water in and around their homes, use mosquito nets or repellents, and take other protective measures,” the official stated. 

He also mentioned that vaccination campaigns—particularly for yellow fever, which requires only one dose—are underway in port and airport areas to prevent the current outbreak, centered in Tolima, from spreading to the department. 

Factors that explain the expansion 

Aedes aegypti larvae, bred at UdeA’s PECET and infected with Wolbachia bacteria, as part of efforts to prevent dengue transmission. Photo: UdeA Communications Directorate / Alejandra Uribe F. 
 
During a 2023 seminar organized by the Pan American Health Organization (PAHO), experts concluded that climate change and unplanned urban expansion have created favorable conditions for the spread of diseases such as dengue and chikungunya. These patterns are now evident in northern Florida, in European countries such as Italy and Spain, and regions of the Southern Cone of South America located south of the Tropic of Capricorn. 

Furthermore, many cities and municipalities have yet to identify and prioritize hot spots—the principal sources of contagion—as recommended by both PAHO and WHO. 

PAHO advises countries to reinforce vector control, improve diagnostic capabilities in health systems, provide timely and effective patient care to prevent serious complications, continue public education campaigns to minimize mosquito exposure and eliminate mosquito breeding and incubation sites. 

While Brazil, Colombia, and Peru report the majority of cases in the Americas, the exact hotspots within their urban centers remain unclear. Physician Guillermo Rúa Uribe noted, “Because authorities have not identified the areas with the highest transmission, they are focusing on reactive disease-control measures instead of proactive prevention. That’s why we can say the response is more reactive than proactive.” 

The expert also pointed out that while we recognize the link between these diseases and climate, researchers still need to conduct more studies to clarify this connection and explore alternative vector control methods. 

Rúa Uribe also emphasized that many local health entities operate without enough scientific data, causing them to prioritize reactive responses over preventive campaigns. “Building a stronger partnership between these organizations and academia is essential,” he said, “so researchers can clarify transmission mechanisms and support more effective disease control.” 

The figures for some diseases 

In January, the World Health Organization (WHO) released epidemiological alerts. In January, the World Health Organization (WHO) released epidemiological alerts. Since then, the country’s health authorities have tracked diseases such as dengue, yellow fever, measles, and avian influenza, with a special focus on the Americas. 

According to the National Institute of Health (INS) epidemiological bulletin, the country recorded 58,800 new dengue cases by the first week of May 2025, resulting in an incidence rate of 142.6 cases per 100,000 inhabitants. 

By early May 2025, Colombia had confirmed 83 cases of yellow fever, resulting in 25 deaths. On February 28, 2025, the World Health Organization (WHO) issued a measles warning after detecting 268 infections across the Americas, a region mentioned as measles-free until 2024. Since then, the WHO has reported 164 cases in the United States, 96 in Canada, and four cases each in Mexico and Argentina. As of mid-March, Colombia had no confirmed measles cases but was investigating several suspected cases. 

Between 2022 and early March 2025, the WHO recorded 4,713 avian influenza (H5N1) outbreaks in animals across 19 countries in the Americas, involving both birds and mammals. During this time, 74 human cases were reported, with 71 occurring in the United States. Colombia reported 71 outbreaks, all involving birds—both wild and domestic poultry.