Epidemiological Analysis of Avian Influenza in the Americas With Emphasis on Brazil: Paho Data From 2024 to the 25th Epidemiological Week of 2025

Avian influenza is caused by viruses of the Orthomyxoviridae family and primarily affects birds, and in some cases can infect humans. Subtypes may be of low pathogenicity (LPAIV) or high pathogenicity (HPAIV), with some zoonotic strains transmitted through contact with infected birds or contaminated environments. This study aims to analyze epidemiological data on avian influenza outbreaks in the Americas, with emphasis on Brazil, from 2024 to the 25th epidemiological week of 2025. An analysis was performed using data provided by the Pan American Health Organization (PAHO) through an interactive surveillance dashboard for avian influenza A(H5N1) in the Americas. The platform was developed to monitor outbreaks in birds, mammals, and humans, with data supplied by the World Organisation for Animal Health (WOAH) and features such as a timeline and detailed outbreak information since 2020. Between January 2024 and June 2025, 72 human cases of avian influenza A(H5N1) were confirmed in the Americas, with two deaths recorded—one in Mexico and one in the United States. The most frequent symptoms included conjunctivitis (72.2%), fever (36.1%), cough (22.2%), and headache (16.7%). In the same period, 916 outbreaks in birds and 1,084 in mammals were reported, involving wild and domestic species. Peru led Latin America with 75 outbreaks, mainly in domestic birds, followed by Brazil (19), Mexico (17), Colombia (8), Argentina (2), and Ecuador and Panama (1). Outbreaks were predominantly in domestic birds, except in Brazil and Mexico, where cases were mainly in wild birds. Brazil reported 18 outbreaks in wild birds and 1 in a domestic bird, with no involvement of mammals or human infections to date. In contrast, Argentina reported one outbreak in a wild mammal. Avian influenza shows higher incidence in countries such as Peru and Mexico. In Brazil, cases remain restricted to wild birds, with an isolated episode in a commercial flock, controlled through sanitary culling and containment measures. Brazilian exports were temporarily affected in the external market, reinforcing the importance of continuous surveillance in areas at the interface between wildlife and industrial poultry production.