The spread of bird flu to a growing number of species and regions has increased the risk of humans being infected by the virus, according to the head of the World Organisation for Animal Health (WOAH). The U.S. reported cases in dairy cows and a person in Texas, with concerns about potential transmission between cows. The virus has led to culling of millions of poultry globally, mainly carried by migrating wild birds. The virus has spread to new regions, affecting a variety of animals, including foxes, cats, tigers, seals, dolphins, and bears. The concern is the higher viral load and potential contamination of humans. There have been outbreaks of bird flu causing serious infections in people with close contact with infected animals, but no sustained human-to-human transmission observed. Scientists warn of the risk of the virus mutating to be transmissible between mammals, including humans, potentially leading to a large-scale pandemic.