As of April 30, 2024, the World Health Organization (WHO) has reported over 7.6 million dengue cases worldwide, including 3.4 million confirmed cases, over 16,000 severe cases, and more than 3,000 deaths. This alarming rise in dengue cases is part of a broader trend observed over the last five years, with the increase being particularly significant in the Region of the Americas, where the number of cases has already surpassed seven million by the end of April 2024. This figure exceeds the previous annual high of 4.6 million cases recorded in 2023.
Significant Increase in the Americas
The Region of the Americas has seen an unprecedented surge in dengue cases, tripling the number reported during the same period in 2023. Factors contributing to this increase include an early start and prolonged duration of dengue transmission seasons, changing distribution and abundance of the mosquito vectors (Aedes aegypti and Aedes albopictus), and the impacts of climate change, such as heavy precipitation, humidity, and rising temperatures that favor mosquito reproduction and virus transmission.
Global Transmission and Reporting Challenges
Currently, 90 countries have reported active dengue transmission in 2024, although not all cases are captured in formal reporting due to weak detection and reporting mechanisms in many endemic countries. The true global burden of dengue is therefore underestimated. WHO emphasizes the need for robust, real-time dengue surveillance to address concerns about undetected cases, co-circulation with other arboviruses, misdiagnosis, and unrecorded travel movements, which could contribute to the unrecognized spread of the disease and the risk of local transmission in non-endemic countries.
WHO’s Response and Surveillance System
To enhance global surveillance and monitor dengue trends and incidence, WHO has established a global dengue surveillance system with monthly reporting across all regions. The newly launched dashboard (https://worldhealthorg.shinyapps.io/dengue_global/) provides data from 103 countries, including 28 that report zero cases. This system aims to provide a comprehensive overview of dengue’s global impact and support timely interventions.
Contributing Factors to Dengue Spread
Several factors are associated with the increasing risk of dengue epidemics and its spread to new areas:
Early and prolonged dengue transmission seasons in endemic regions.
Increased abundance and distribution of mosquito vectors.
Climate change effects, including El Niño and La Niña events.
Changing serotypes affecting population immunity.
Fragile health systems in politically and financially unstable regions.
Large-scale population movements and the global movement of people and goods.
Global Health Risk
Given the current scale of dengue outbreaks, the potential for further international spread, and the complexity of transmission factors, WHO assesses the global dengue risk as High. Dengue remains a significant global public health threat.