First Documented Case Of Cow-To-Human Transmission Of Bird Flu Causes Alarm Among Health Experts

The Centers for Disease Control and Prevention (CDC) recently reported that the H5N1 avian flu, commonly known as bird flu, has spread to 36 dairy cow herds across nine states since April 30. 

Birds, like humans, are susceptible to influenza; when birds contract the flu, they can transmit it to other poultry species, such as chickens, ducks and turkeys. However, the current strain of avian influenza, H5N1, has crossed species barriers, infected dairy cows and even transmitted from cows to humans. This is the first documented case of cow-to-human transmission, and the most recent human case of H5N1 infection occurred in April 2022 in Colorado, where the individual contracted the virus from poultry.

The U.S. Department of Agriculture (USDA) has taken measures to address the situation, including collecting ground beef samples from retail stores in states affected by the bird flu outbreaks. The samples will be tested to determine the presence of viral particles. Previous studies have found viral particles in cow’s milk samples, with as many as 1 in 5 samples testing positive.

As part of containment efforts, the USDA has mandated that dairy cows test negative for bird flu before being transported across state lines. This decision follows criticism from infectious disease experts who argued that insufficient testing has hindered an accurate assessment of the outbreak’s scale.

A study published in Emerging Infectious Diseases revealed that cats died after consuming raw colostrum from infected cows, indicating the potential for cross-species transmission of the H5N1 virus within mammal populations.

Public health experts are concerned that as the virus continues to jump between animals and potentially humans, it increases the likelihood of mutation, human-to-human transmission, and establishment within the human population. Certain strains of H5N1 have demonstrated a 50% mortality rate in humans, although the confirmed case resulting from infected cows was mild. Epidemiologists and infectious disease experts have criticized the government’s response and have called for swift action to contain the spread among animal populations.

The USDA has assured the public that the meat supply is safe and pasteurized milk remains safe for consumption. However, Colombia has imposed restrictions on the transportation of beef from U.S. states where dairy herds have tested positive for bird flu.