Climate change, unplanned urbanization, sprawling cities, and the El Niño effect have combined to make 2024 a “historic” year for dengue transmission in the Americas. Aedes aegypti mosquitoes, the primary vector for dengue, found increased opportunities to breed, driving cases to a record 12.7 million in the WHO’s Americas Region—nearly triple the 2023 figures.
This surge translated to roughly 21,000 severe cases and over 7,700 deaths, with more than one-third of the severe cases affecting children. Countries such as Guatemala reported alarming child mortality rates, with 70% of dengue-related deaths occurring in children. Brazil bore the brunt of the outbreak, accounting for 80% of cases, followed by Argentina, Colombia, and Mexico, where 88% of dengue-related deaths were concentrated.
PAHO leadership attributed this spike to climate-related factors such as droughts, floods, and warmer temperatures, which facilitated mosquito breeding, alongside unplanned urbanization and inadequate infrastructure for water and waste management. Despite these challenges, PAHO expressed cautious optimism for 2025, citing improved case management, community engagement, and the rollout of dengue vaccines.
Beyond dengue, the Americas faced emerging threats in 2024, including Oropouche fever and avian flu. Oropouche, a rare arbovirus transmitted by midge mosquitoes, surged to 12,000 cases, predominantly in Brazil, with reports of severe fetal outcomes such as congenital abnormalities and infant microcephaly. These developments prompted travel advisories for pregnant women to affected regions.
Meanwhile, North America grappled with an ongoing H5N1 avian flu outbreak, with 58 human cases reported in the U.S. and concerns over potential human-to-human transmission. PAHO emphasized the importance of genomic surveillance and a One Health approach to address these challenges, especially given the virus’s spread to dairy cattle.
Measures like milk pasteurization were highlighted as critical public health interventions to mitigate risks. As health threats multiply, PAHO underscored the need for cross-border collaboration, robust surveillance, and strengthened health systems to protect vulnerable populations, including migrants, who face unique challenges in accessing care.
