Bird flu in milk: Is it safe for humans?

Bird flu, also known as avian influenza, primarily infects birds but can also affect humans. Amidst this outbreak, a recent report from the US Food and Drug Administration (FDA) identified traces of the H5N1 virus in raw milk, highlighting concerns about potential transmission to humans. This means that there are possibilities that consuming milk from infected cows could transmit bird flu to people. While its origins date back to 1996, in March 2024, the H5N1 virus was detected in US dairy cattle for the first time. Known for causing deadly infections in poultry, it has been reported to have infected cows and a person in the US. 

Bird flu in cow milk

The researchers of US Food and Drug Administration (FDA) collected 275 samples of raw milk from bulk storage tanks on farms across four states where dairy cattle had tested positive for H5N1. They found that the virus was present in 57.5 percent of the samples, and further analysis revealed that a quarter of these contained infectious virus. This confirms that raw milk contaminated with the virus is unsafe for human consumption. Fortunately, pasteurization, which involves using high heat to eliminate harmful microbes in foods, effectively destroys the virus in the milk and make it safe.

Can you get bird flu from cow milk?

In late March of this year, the first outbreak of the HPAI H5N1 virus in dairy cows in the US was reported. Three cases of people working closely with these cows tested positive for H5N1 virus, with mild symptoms. Although the risk of direct transmission to humans remains low, there is concern among researchers about potential infections via the consumption of raw milk. Therefore, the FDA strongly cautions against consuming raw milk.

Is pasteurised milk safe?

Raw milk can harbour harmful bacteria like the H5N1 bird flu virus, Salmonella, E. coli, and Listeria, among others, posing health risks and potentially leading to diseases such as H5N1 influenza. Therefore, it is crucial to consume only pasteurized milk. Pasteurization involves heating milk to eliminate pathogens such as the H5N1 virus, leaving non-infectious, inactive fragments of the virus behind.

In an initial study, the FDA examined 297 commercial dairy products from 38 states in the US and found high-pathogenic avian influenza (HPAI) viral particles in one out of every five samples. However, tests on pasteurized milk came negative, indicating no presence of live H5N1 bird flu virus and confirming that pasteurized milk is safe for consumption.

Also read: Is it safe to eat chicken during bird flu?

Risk of bird flu in humans

The widespread distribution of highly pathogenic Avian Influenza or HPAI A (H5N1) viruses among wild birds, poultry, and certain mammals, including cows, increases the potential for human exposure to these viruses. Over the past two decades, approximately 900 cases of infection with the avian influenza virus H5N1 have been reported in humans. Most individuals affected had close contact with infected birds. Previous strains of H5N1 virus have proven deadly for people, resulting in fatalities in about half of reported cases, according to the National Institute of Health. However, these viruses cannot spread from human-to-human transmission, which limits their pandemic potential.

According to the Centers for Disease Control and Prevention (CDC), the current risk of bird flu viruses affecting the general public remains low. Nonetheless, individuals with occupational or recreational exposure to infected birds or animals, including cows, face a heightened risk of contracting the HPAI A (H5N1) virus.

Also read: H5N2 bird flu infects 4-year-old in India, first human case since 2019: WHO

What are the symptoms of H5N1 bird flu?

According to CDC, in humans, avian influenza A (H5N1) and A (H5N6) viruses, as well as avian influenza A (H7N9) virus, are responsible. Common symptoms of bird flu include:

• Fever
• Cough
• Runny or stuffy nose
• Sore throat
• Muscle ache
• Shortness of breath
• Respiratory difficulties
• Headache

In severe cases, H5N1 bird flu can lead to pneumonia, acute respiratory distress syndrome, organ failure, and death.

The disease, which was first reported in Vietnam in 2003, has caused human outbreaks and fatalities across Asia, Europe, Africa, and the Middle East. To date, at least 356 deaths have been attributed to bird flu, according to the World Health Organization.