California officials have declared a state of emergency due to the widespread infection of bird flu affecting dairy cows in the region, along with sporadic cases in humans throughout the country. This escalation has prompted concerns regarding the nature and behavior of the virus, which is prevalent in wild birds, commercial poultry, and various mammal species.
The strain known as Type A H5N1 was first identified in U.S. dairy cattle back in March. Since then, there have been confirmed cases in at least 866 herds across 16 states. In total, more than 60 individuals in eight states have contracted the virus, with most cases resulting in mild symptoms. However, health officials reported the first severe case in Louisiana, where the patient required hospitalization due to serious illness from the virus.
In response to the crisis, Governor Gavin Newsom has stated that the declaration aims to facilitate a faster and more effective response to the outbreak by ensuring that state resources are readily available. Authorities have been actively testing large milk tanks during processing and are tracking the virus, which has reportedly affected approximately three-quarters of the infected dairy herds in the U.S. Recently, the virus was detected on dairy farms in Southern California after its presence was confirmed in the Central Valley since August.
The Centers for Disease Control and Prevention (CDC) has reassured the public that the risk posed by the virus is currently low. There have been no indications of human-to-human transmission, nor signs that the virus has mutated to allow easier spread among people. Experts in the field of influenza believe it is premature to predict the future course of the outbreak, although they remain cautious due to the unpredictable nature of flu viruses that may mutate over time.
This week marked the first confirmed case of severe illness due to bird flu in the U.S., where all previous infections were mild. The critically ill patient from Louisiana is over 65 years old and has underlying health conditions. The CDC noted that this case is linked to exposure to a backyard flock of sick birds, which was a significant development as it marks the first known instance in the U.S. associated with backyard birds. Meanwhile, testing confirmed that the strain responsible for this patient’s illness is the same as that found in wild birds but not in cattle.
As the number of infections increases, the potential for more severe cases might also rise, suggested a virus expert from the University of Saskatchewan. Globally, nearly 1,000 H5N1-related illnesses have been documented since 2003, with a mortality rate of over half among those infected.
To protect themselves, individuals who interact with dairy cows, commercial poultry, or backyard birds should take precautions such as wearing respiratory protection, eye protection, and gloves. Public health experts recommend careful handling of any birds showing signs of illness. Additionally, the CDC is subsidizing flu vaccinations for farmworkers to mitigate the risk of co-infection with different flu strains that could lead to mutations of the virus.
Aside from direct animal interactions, the H5N1 virus can also be transmitted through raw milk. Pasteurization effectively kills the virus, making pasteurized milk safe for consumption. However, instances of the virus being present in unpasteurized milk have prompted recalls in California after it was detected at certain farms. Notably, two indoor cats in Los Angeles that consumed the recalled raw milk suffered fatal consequences due to bird flu.
Given these developments, health officials continue to advise against raw milk consumption to reduce exposure to not only bird flu but other potential pathogens as well. In light of the growing concern, the U.S. Department of Agriculture has increased testing of raw milk across the nation, implementing mandatory testing in 13 states to monitor and address the outbreak effectively.