With rising bird flu cases among poultry and dairy cattle, human infections are also beginning to surface. Many people are now wondering if they could be at risk from this highly contagious avian influenza virus.
Although rare, bird flu infections in humans are becoming more concerning. In the United States alone, 61 human cases of bird flu have been reported this year, according to the Centers for Disease Control and Prevention (CDC). Almost all these cases involve individuals who work closely with poultry or dairy cattle, except for three instances.
Why Does Bird Flu Primarily Infect Birds?
As the name suggests, bird flu viruses—specifically H5N1, the strain driving the current outbreak—prefer to infect birds. These viruses attach to sialic acid receptors, which are abundant in the respiratory tracts of birds. This preference makes birds highly susceptible to the virus.
However, flu viruses are known to mutate quickly. Since 2022, the H5N1 virus has been infecting an increasing number of mammals, including dairy cattle. Scientists are monitoring this development closely, as frequent mutations improve the virus’s ability to adapt to new hosts, including humans.
The Threat of Virus Mutations
A recent study published in the journal Science revealed that a single genetic mutation in the H5N1 virus could allow it to bind to sialic acid receptors found in the human respiratory tract. While this possibility is concerning, experts note that predicting when or if such a mutation might occur is incredibly challenging.
How Does Bird Flu Spread to Humans?
In nearly all reported cases, bird flu infections in humans have resulted from direct contact with infected animals. These incidents, referred to as spillover events, typically happen when individuals handle sick birds, dairy cattle, or contaminated environments.
Most human infections have been mild, but severe cases have occurred. For example, the first severe case in the United States was recently reported in Louisiana. The individual had been exposed to sick and dead birds on their property and is currently hospitalized in critical condition.
Notably, there is no evidence of human-to-human transmission of H5N1 in the United States. According to the CDC, the risk of widespread infection remains low.
High-Risk Groups for Bird Flu
Certain groups of people are at greater risk of contracting bird flu:
- Farm Workers: Individuals working on poultry or dairy farms are frequently exposed to the virus through bird saliva, mucus, feces, and contaminated barn environments. The virus can become airborne when feathers and litter are disturbed during activities like culling.
- Backyard Poultry Keepers: People raising small flocks at home are also vulnerable, especially if their birds contract the virus.
For dairy farm workers, milking cows present a unique risk. The virus can contaminate raw milk, and workers may become infected if raw milk splashes into their eyes or if they handle milk with bare hands and then touch their faces.
Symptoms of Bird Flu in Humans
One of the most common symptoms in infected farm workers is red, irritated eyes, also known as conjunctivitis. This may occur because human eyes have sialic acid receptors similar to those found in birds.
Is Raw Milk a Risk?
Raw milk has been a point of concern due to its potential to harbor bird flu and other harmful pathogens. Studies have detected high concentrations of the virus in raw milk from infected cows.
Although no human infections have been directly linked to drinking raw milk, its risks cannot be ignored. For example, a toddler in California recently tested positive for influenza after consuming raw milk. While the CDC could not confirm it was bird flu, the case highlights the potential danger.
Beyond bird flu, raw milk has been associated with outbreaks of pathogens like E. coli, salmonella, listeria, and Campylobacter. Pasteurization effectively kills these harmful germs, including the H5N1 virus. However, refrigeration alone is insufficient, as flu viruses can remain infectious in raw milk for up to five days.
How to Stay Safe from Bird Flu
To reduce the risk of bird flu infection, the CDC recommends:
- Avoid Sick Animals: Steer clear of sick or dead birds and livestock. Avoid handling surfaces contaminated with bird feces, saliva, or litter.
- Wear Protective Gear: If you must handle infected animals, wear personal protective equipment (PPE) such as:
- Goggles
- Disposable gloves
- An N95 face mask
- Coveralls
- Rubber boots
- Stick to Pasteurized Dairy Products: Avoid raw milk, as it can carry multiple pathogens, including the bird flu virus. Opt for pasteurized products instead.
- Cook Eggs and Poultry Thoroughly: Even though safeguards are in place to prevent contaminated eggs from reaching store shelves, it’s wise to cook eggs and poultry to a safe internal temperature.
Final Thoughts
While the overall risk of bird flu to the general public remains low, staying informed and cautious is essential, especially for those in high-risk occupations or environments. By following CDC guidelines and avoiding potential sources of infection, you can significantly reduce your chances of contracting the virus.