Avian or bird Flu A (H5N1): ¿a pandemic to come in humans?

Abstract

Avian influenza or bird flu is caused by a virus of the Orthomyxoviridae family and mainly affects birds. The objective of this review is to provide an overview of avian influenza, especially type A (H5N1), with its epidemiological evolution and to describe how it could infect humans and cause a pandemic. Avian influenza A viruses first appeared in southern China in 1996, causing large outbreaks in poultry in 1997. These outbreaks were controlled, however, the virus was not eradicated from poultry, reappearing in 2003. Avian influenza A is now widespread in wild birds worldwide. Since 2020, cases have been reported in cattle and poultry infected with highly pathogenic avian influenza due to the genetic reassortment mechanisms of the virus. Although the risk to the human population is low, some cases in humans have been reported since 2022. In 2024, the United States (US) raised the alert after an outbreak was reported among dairy and poultry farm workers, triggering detection and prevention measures. Although the number of human cases infected with avian influenza has been increasing over time, the risk of a pandemic is still low, given the effective public health measures.