Ongoing outbreaks of avian influenza, commonly known as bird flu, have been causing devastation to poultry flocks and wild birds in the United States and worldwide. The H5N1 virus responsible for these outbreaks has been making a concerning transition to mammals, with cases identified in cats, goats, and raccoons. In the US alone, the virus has spread to 170 dairy herds across 13 states, with health officials confirming the first case of a dairy worker contracting the virus from an infected cow in April.
Recently, there has been an increase in the number of human cases of bird flu. The US Centers for Disease Control and Prevention reported three new cases on July 25, bringing the total to 13 cases since April. These cases were among individuals who had direct contact with infected poultry at an egg farm in Colorado. Fortunately, all three individuals are experiencing mild symptoms and have been offered antiviral treatment.
Experts like Stephen Morse, an epidemiologist at Columbia University, emphasize that the risk of human-to-human transmission remains low at this point. However, the CDC is investigating whether the workers in Colorado were following proper safety protocols, such as wearing personal protective equipment (PPE). Historically, most human cases of bird flu have occurred in individuals who were not wearing recommended PPE.
The recent cases follow a cluster of infections identified earlier this month among poultry workers at a different facility in Colorado. These cases were linked to the culling of birds infected with H5N1, a necessary step to prevent further spread of the virus. With these new cases, Colorado now has a total of nine confirmed cases of bird flu, with additional cases reported in Texas and Michigan, also related to exposure to infected dairy cows.
Research has shown that the virus can remain stable on milking equipment, increasing the risk of transmission through raw milk. However, pasteurization effectively eliminates the H5N1 virus, underscoring the importance of proper food safety practices. While all reported cases in the US this year have resulted in mild symptoms, the historical lethality rate of H5N1 is around 50 percent, with nearly 500 deaths reported between 2003 and 2023.
The last major outbreak of bird flu among US poultry flocks occurred in 2015, resulting in the loss of millions of birds. The first reported human case of bird flu in the US was in 2022, and the recent increase in cases raises concerns among experts like Anice Lowen, a flu researcher at Emory University. The reasons behind this resurgence in human cases remain unclear and warrant further investigation to better understand and address this growing threat.
