Bird Flu Cases In Humans: Here's What To Know

DISS, UNITED KINGDOM - NOVEMBER 13: DEFRA (Department for Environment, Food and Rural Affairs) ... [+] workers clear up dead turkey carcasses at Redgrave Park Farm where around 2,600 birds, including ducks and geese, are being slaughtered following the confirmed outbreak of the H5 strain of bird flu, on November 13, 2007 in Redgrave, Suffolk, near Diss, Norfolk, England. (Photo by Jamie McDonald/Getty Images)

You’ve probably heard about the avian flu infecting and killing millions of birds in the last several decades, then spreading to poultry and cattle.

Since 1997, fewer than 1,000 cases of bird flu, a type of Influenza A virus, have been reported globally in humans from 23 countries. The highly pathogenic strain of Influenza A H5N1 is the one most responsible for infection in humans, and most occur after poultry exposure.

The virus spreads through direct contact with sick and infected animals through their bodily fluids like saliva, feces and respiratory droplets. Humans can acquire the virus if they directly touch these fluids and then touch their eyes, nose or mouth. We can also get infected by breathing small dust particles in animal habitats where the virus lives.

You will not get the bird flu from eating properly cooked poultry or eggs. Although bird flu viral particles have been found in milk sold at U.S. grocery stores, you are not likely to get infected by drinking pasteurized milk as all available evidence at this time indicates that it’s safe. In fact, the FDA recently released a statement confirming the safety of pasteurized milk despite the presence of inactive viral particles of bird flu in commercialized milk sold in stores through preliminary results of egg inoculation tests.

To date, only two cases of bird flu have been reported in humans in the United States: one from a poultry worker in Colorado in 2022 and one from a Texas dairy worker this March. In both cases, symptoms were mild and the individuals survived with no complications. Common symptoms for the bird flu are similar to the common flu in humans—fever, sore throat, cough, runny nose, watery eyes, muscle aches and fatigue. Occasionally, bird flu can cause more severe symptoms such as pneumonia (infection of the lung) or respiratory failure.

Importantly, the mortality rate of bird flu in humans is 56%, according to the World Health Organization, meaning more than half of individuals who get it will die from the virus. However, this high number is likely exaggerated as health officials do not know exactly how many humans have had the virus but showed no symptoms and weren’t tested. Testing usually occurs with a nasal or throat swab, and many farmers or those who work with animals may not know they have an infection or may be reluctant to get tested.

While there can be rare instances of human-to-human transmission of bird flu, there have been no such cases in the United States. Cases in America have been isolated and have been from direct contact with animals presumed to have been infected with the virus.

Should we be worried about the next pandemic then given how widespread bird flu is among animals? Never say never, but it does not appear that bird flu is highly contagious in humans yet. Emergence of a pandemic would require many things, among which would be a high level of sustained human-to-human spread, which certainly does not appear to be the case with bird flu. Of course, this could change as the bird flu virus mutates, which viruses do all the time as they replicate and interact with the environment and in different hosts.

An important area of surveillance would be if bird flu spreads among pigs. They can serve as mixing vessels because they are able to be infected by both human and avian influenza viruses. In theory, this could allow for the production of recombinant strains and mutations that could more efficiently infect humans.

The good news is that Tamifu, an antiviral medication used to treat the common flu in humans, is also effective at treating bird flu should it occur in humans, according to the Cleveland Clinic. In the unlikely case of a future bird flu pandemic in humans, a vaccine is currently being developed by the U.S. government should it be needed, according to the CDC.

For now, infections in animals and humans should be closely monitored.