Bird Flu’s Spread to Cows and Humans Raises Pandemic Alarm

The recent spread of H5N1 avian flu to dairy cows and the infection of at least one dairy farm worker in Texas represent a concerning development in the virus's behavior, challenging previous understandings of its transmission and adaptability across species and raising alarms about the virus’s pandemic potential.

The first cases of the H5N1 bird flu strain in North America were reported among wild migratory birds in late 2021 before spreading to poultry farms and, more recently, to dairy cattle. The virus has now infected dairy herds in nine U.S. states. The outbreak has led to the loss of more than 90 million poultry in the United States, with economic damages estimated to be between $2.5 and $3 billion. Widespread culling of poultry worldwide, as a response to the bird flu, is intensifying the rise in global food prices.

Comparing H5N1 to COVID-19

According to the World Health Organization (WHO), nearly 900 people have been diagnosed with bird flu globally, and more than 460 have died. That means the virus’s fatality rate among humans is around 52 percent, compared to COVID’s current fatality rate of less than 0.1 percent (and early pandemic fatality rate of about 20 percent). Experts warn that if it begins to spread among humans, avian influenza could be 100 times worse than COVID. According to bird flu researcher Dr. Suresh Kuchipudi, “This virus [has been] on the top of the pandemic list for many, many years and probably decades … And now we are getting dangerously close to this virus potentially causing a pandemic.”

The Evolving Virus and Potential for Human Transmission

Echoing these concerns, a new report by the European Food Safety Authority (EFSA) notes that should the virus spread to people, “large‐scale transmission could occur due to the lack of immune defenses against H5 viruses in humans.” The WHO also flags that within the virus, “some genetic mutations are present which have been demonstrated to increase the ability to bind to human-like receptors.” The virus continues to evolve rapidly, and, the WHO says, “studies are underway to identify any changes in the virus that may help the virus to spread more easily among mammals, including humans.”

"This virus has the potential to seriously disrupt our agricultural supplies and also jump from other mammals to humans and become an epidemic or even a pandemic," warns Dr. Michele Barry, director of Stanford University’s Center for Innovation in Global Health and senior associate dean of global health.

H5N1 in the Animal Kingdom

Cases of H5N1 have been detected in hundreds of animal species, including many that live within close proximity to humans. In addition to cattle, poultry, and common wild birds such as ducks and pigeons, the virus has been found in over 200 mammal species including cats, dogs, pigs, squirrels, goats, opossums, raccoons, and animals used in fur farming such as minks and foxes. The EFSA report highlights the risk for these species to serve as “bridge hosts” between animals and humans, facilitating evolution of the virus to a more dangerous strain. Pigs are of particular concern; they are known as “mixing vessels” because they can be infected by bird, pig, and human influenza viruses. Researchers consider live animal markets and large-scale industrial livestock operations — both of which house large numbers of immunocompromised animals in confined quarters — to be the most likely epicenter of the next pandemic.

Food Safety Concerns

Also cause for concern is the potential for the avian flu to spread to humans via infected milk, meat, or eggs. Scientists have detected the virus in dairy milk and in meat. A recent FDA investigation found that 1 in 5 samples of pasteurized milk in U.S. grocery stores tested positive for the virus.

U.S. federal agencies claim that, if cooked properly, animal products are likely safe to eat even if they originate from infected animals. However, some epidemiologists disagree and warn that pasteurization of milk may not neutralize viruses sufficiently to prevent them from infecting humans. They also argue that the USDA and CDC have presented no evidence that avian flu cannot survive pasteurization in milk.

Ecological Impact

In addition to the threat H5N1 poses to humans, the virus’s spread among various animal species has driven a large-scale ecological crisis. Polar bears, seals, Antarctic penguins, and many other animals in more remote regions of the world have already succumbed. Scientists have raised repeated concerns about dire consequences for wild animal populations.

Avian influenza is just one of many diseases that has spread among livestock and wildlife in recent decades; others include foot-and-mouth disease, mad cow disease, African swine fever, and more. 

Root Causes in the Food System

It’s clear that a number of developments within the food sector, including the encroachment of agricultural operations into wildlife habitats, the overuse of antimicrobials in feed, and the increasing intensification of livestock farming have led to tremendous biosecurity vulnerabilities that amplify the risk of a global health crisis.