Another person has tested positive for avian influenza, also known as bird flu, as part of a global outbreak that has affected wild birds, poultry, and other animals. In the United States, a highly contagious strain of avian influenza A (H5N1) has been identified in cows in nine states, as well as in a dairy worker in Texas. This marks the first instance of cow-to-human transmission of this strain, according to the U.S. Centers for Disease Control and Prevention. Bird flu is caused by infection with avian influenza A viruses that are commonly found in wild aquatic birds and domestic poultry.
Australia recently reported its first human case of H5N1 in a child who contracted the virus while traveling in India. Despite developing a severe infection, the child has since recovered. Health officials in Australia confirmed that the recent human cases of H5N1 were caused by a highly pathogenic strain of the virus, different from the one causing the outbreak in the U.S. Although there has been no known human-to-human spread of the current H5N1 strains, health agencies worldwide are closely monitoring the situation to prevent any further spread of the virus.
Bird flu viruses occasionally infect mammals and, in rare cases, humans. The chief scientist of the World Health Organization has expressed concern about the potential for the virus to acquire the ability to spread efficiently among humans. The highly pathogenic H5N1 strain causing the outbreak in the U.S. is severe and often fatal in birds but appears to be mild in cows. However, traces of the virus have been found in cow’s milk. Symptoms of bird flu in humans can vary from mild flu-like illness to severe complications like pneumonia and respiratory failure.
Bird flu infections in humans can present with a range of symptoms, including fever, cough, muscle aches, headache, fatigue, gastrointestinal issues, and respiratory problems. In severe cases, bird flu can lead to pneumonia and other complications that require hospitalization. Recovered cases have included a child in Australia with symptoms of severe infection and a dairy worker in Texas who experienced only eye inflammation. Lab testing is required to diagnose bird flu, as signs and symptoms alone are not sufficient.
Transmission of bird flu viruses to humans is quite rare, with more cases occurring directly from infected birds, contaminated environments, or potentially through an intermediate host. Infected birds shed the virus in their secretions and excretions, making respiratory exposure a common route of infection. Human-to-human transmission of bird flu viruses has been documented in only a few cases through close, prolonged contact between symptomatic individuals and caregivers. Experts emphasize the importance of preventing the spread of bird flu through avoidance of direct contact with birds and effective hygiene practices.
Preventing bird flu requires avoiding direct contact with wild birds, visiting poultry farms, or wearing appropriate protective gear when interacting with birds. Past evidence indicates that properly cooked poultry, eggs, and beef are safe to consume, as well as pasteurized milk. Despite the low risk of human transmission, health agencies recommend seeking medical attention if symptoms of bird flu develop after contact with birds. Surveillance and monitoring of bird flu viruses are ongoing to identify any potential changes that could enable more efficient human-to-human transmission.
