Navigating Bird Flu Concerns

ChickensBird flu is rapidly spreading throughout poultry in the U.S. At the time of this article, approximately 163 million birds have been affected by the virus, according to the Centers for Disease Control. Fears of further infections in chickens have led to the mass culling of flocks, causing a shortage of eggs and a spike in prices that have impacted consumers and small businesses throughout the country. Dairy cattle are also affected, with the virus having been isolated from raw milk.  

For many still reeling from COVID-19, bird flu’s effects on livestock have sparked concerns of another pandemic. Right now, however, only 70 people have tested positive for bird flu in 12 states. These infections have mostly involved farm workers who were in close contact with poultry or dairy cows, but physicians and researchers are monitoring the situation to see whether the virus begins to spread to a larger population. According to clinical microbiologist Reeti Khare, PhD, the main way this would happen would be through mutation. Because bird flu is an RNA-based virus, it changes more rapidly. “COVID and the flu are RNA viruses, which is why we are concerned every year about new mutations, new strains,” said Dr. Khare. “Another problem with influenza is that its strains also can infect a variety of hosts — chickens, ducks, cows, humans. So now, you’re not just dealing with two human strains; you’re shuffling a chicken strain with a human strain, and so on. Eventually, you’ll wind up with a ‘Frankenvirus,’ which can get spread easily and cause severe disease.”

An example of the virus’s versatility can be seen in the way bird flu has infected cats through exposure to unpasteurized or raw milk from cows with bird flu at dairy farms. Because this form of transmission could affect humans as well, infectious disease expert Jared Eddy, MD, cautioned against consuming unpasteurized milk. “The pasteurization process kills the virus,” said Dr. Eddy. “By drinking raw milk, you’re putting yourself at risk.”

When it comes to human-to-human transmission of bird flu, there are still no confirmed cases. “We have seen sustained transmission of this bird flu in cows, but fortunately this hasn’t happened yet in humans,” said Dr. Khare. “We also don’t know how people are getting it yet, whether it’s through respiratory transmission or other secretions. But the larger the load you’re exposed to, the greater the chance of infection. Farm and dairy workers who are exposed to the bird flu virus in larger quantities are more likely to catch the virus right now.”
 

Why Bird Flu Is Not Spreading in Humans Yet

“If we have millions of birds infected and less than 100 humans, that suggests the virus is not very transmissible yet,” said Dr. Khare. So why isn’t bird flu spreading among humans?

The answer lies in biology. In order for a virus to infect a cell, it needs to bind with certain receptors. “It turns out that bird flu infects receptors that aren’t present in the upper respiratory tract of human beings,” said Dr. Khare. “We have those receptors deeper in our lungs. So if we get a big enough exposure and it gets into our lungs, then we’ll get sick. But it has to pass through your upper respiratory tract first.”

However, it’s possible that a new bird flu strain capable of binding with receptors in the upper respiratory tract could emerge. “When that happens, you’re looking at a more worrying scenario,” said Dr. Khare. “Fortunately, this time we’re more prepared with vaccines, masks and antivirals.”


Bird Flu Infection and Prevention

Because bird flu infections among humans have been limited, there are a lot of unknowns when it comes to the symptoms and average severity of the illness. To date, only one person has died of bird flu in the U.S., and that person had underlying medical conditions.

The symptoms being reported among people infected with bird flu include:

  • Body aches
  • Conjunctivitis (“pink eye”) and subconjunctival bleeding (broken blood vessel in the eye)
  • Cough
  • Fever
  • Lower respiratory tract infections

Limiting close contact with birds and livestock is the best way to keep yourself safe from bird flu infection. “It’s also a good idea to keep your domestic animals away from wild birds so that they don't get sick from them, and then you won’t potentially get sick from them,” said Dr. Eddy.

Again, at this time bird flu is only being transmitted from animals to human beings. There have been no cases where humans transmit the virus to other humans during the current outbreak. However, if the virus mutates and becomes more transmissible between humans, a limited supply of flu vaccines reasonably well-matched to bird flu are currently on standby. These vaccines are currently not available for the general public. However, if the virus becomes widespread among humans, physicians expect to be better prepared than they were for the COVID pandemic, when there was no vaccine ready to go.

Additionally, the normal flu vaccine may offer some protection, while also helping to decrease the chances of bird flu mixing with typical flu, according to Dr. Eddy. So, if you didn’t receive your flu shot at the height of the season, now may be the perfect time to visit your doctor or pharmacy.