In recent developments, the H5N1 avian flu virus has been detected in both dairy cattle and poultry farms across the United States. According to preliminary findings from ongoing testing by the Centers for Disease Control and Prevention (CDC), there is little to no pre-existing immunity to this strain of the virus among Americans, as antibody levels were low in people who were or weren't vaccinated against seasonal flu. This suggests that most of the population would be susceptible if the virus changed to a form that more easily spreads among people.
To date, only three human infections have been reported in connection to dairy farm outbreaks, all involving people who worked closely with cows. However, scientists and health officials are concerned about the potential for this virus to mutate and become more transmissible among humans. The World Health Organization (WHO) has identified the first human death from H5N1 in Mexico City.
The USDA Animal and Plant Health Inspection Service (APHIS) has confirmed 102 outbreaks in dairy herds, with the latest confirmations involving 5 farms in Colorado and 1 in Iowa. Additionally, three more outbreaks have been reported by the Iowa Department of Agriculture and Land Stewardship, two more in Sioux County and one in Plymouth County. Meanwhile, Minnesota reported another outbreak in commercial poultry involving a turkey farm with 33,100 birds.
It's important to note that it's extremely rare for the H5N1 virus to spread from one human to another. However, scientists have found that five amino acids must change in the key receptor for bird flu to gain a propensity to bind to a human receptor and then be able to go human-to-human. This is why it's crucial for researchers and health officials to closely monitor the situation and prepare for potential future developments.
The risk of transmission from animals remains low, but people who work with poultry, waterfowl, or livestock are most vulnerable to catching the virus. It's recommended that they take precautions such as wearing protective clothing and practicing good hygiene to minimize their exposure. The CDC advises that cooking poultry and eggs thoroughly kills the virus.
The H5N1 virus was first identified in birds in 1959 but became a cause of concern after an outbreak in Hong Kong in 1997. Since then, it has caused millions of deaths among birds worldwide and over 800 human cases with a mortality rate of around 60%. The current strain has spread quickly and widely, causing animal outbreaks at dozens of dairy cow farms and over 1,000 poultry flocks in the US. Four human infections have been reported in the US among people working at affected farms. Globally, there have been 15 human cases caused by the widely circulating bird flu strain including one death - a 38-year-old woman in southern China in 2022.
