Detección del virus de la influenza A (H5N1) altamente patógeno en aves silvestres acuáticas en Brasil

Resumen

Highly pathogenic influenza A (HPAI) is a disease of worldwide distribution, with pandemic cycles over the years, and with serious consequences for the international trade of poultry products. In May 2023, it was detected for the first time in the national territory, diagnosed in wild birds aquatics, which does not compromise Brazil’s status as a HPAI-free country for international trade. The first case detected occurred in two birds of the species Thalasseus acuflavidus (trinta-réis de bando) and a bird of the species Sula leucogaster (atobá-pardo), in the state of Espírito Santo. All investigation and sampling were carried out as provided for in the avian influenza and Newcastle disease surveillance plan. The diagnosis was carried out in accordance with the provisions of the Terrestrial and Aquatic Animal Health Codes and in the at the official reference laboratory for NCD and AI of the WOAH in Brazil. The execution of the actions to control and confront the HPAI outbreak was carried out by the Institute of Agricultural and Forestry Defense of Espírito Santo (IDAF/ES) in partnership with the Institute for Research and Rehabilitation of Marine Animals (IPRAM), Ministry of the Environment (ICMBio and IBAMA), Beach Monitoring Program (PMP) under the coordination of DSA/MAPA. Most of the outbreaks were identified in wild birds (155), and outbreaks were also detected in backyard birds (3) and marine mammals (5), the latter affecting hundreds of animals, in the states of BA, ES, MS, PR, RJ, RS, SC e SP. Epidemiological surveillance data show that the first outbreak of HPAI in wild birds in Brazil occurred during the period of seabird migration in the Brazilian coastal zone, in populations of terns, during the period from April to September, with regional movements on the coastal islands of the states of Espírito Santo to Santa Catarina. The phylogenetic analysis of the H5N1 clade virus 2.3.4.4b obtained from the first HPAI outbreak in Brazil indicated that the probable source of introduction of the virus was the migration of infected wild birds along the Pacific route. Although Brazil maintains the HPAI-free status in commercially produced birds, the wide dissemination of HPAI virus in populations of free-living wild animals, observed in the national territory, results in a permanent risk of introduction and dissemination of the disease in commercial poultry, with incalculable damage to food safety, public health, the environment and the national economy.