Everything to Know About the Current U.S. Bird Flu Situation—Including What's Going on In Missouri Here's what you need to know about the latest developments
The bird flu situation in the United States has evolved rapidly since April, when news about the virus infecting dairy cows made headlines
- Bird flu started making consistent headlines in April, when the H5N1 strain infected a group of dairy cows in Texas.
- Since then, 17 people have become infected with H5N1, including a person in Missouri who had no known contact with an infected animal.
- Experts say the risk of human-to-human spread remains low, and there's no reason to panic about a potential widespread bird flu outbreak.
The bird flu has consistently been in the news since April, when the H5N1 strain was found to have jumped from wild birds, its typical host, to dairy cows in Texas. Since then, new infections have been reported, including those in dairy cow and poultry workers.
But one case of bird flu in particular has been making headlines—a Missouri resident tested positive for H5N1 in August, but unlike the 17 other known cases, didn’t have any contact with an infected animal. Since the patient was hospitalized in August, reports have swirled about how the person might have contracted the virus and whether they spread it to people around them. If so, it would be the first known human-to-human transmission reported worldwide since 2007.
The most recent U.S. bird flu outbreak has evolved quickly since the spring, and if you haven’t kept up with the headlines—or simply need a refresher—we’ve got you covered. Here’s everything you need to know about the status of bird flu in the U.S. and whether there’s any reason to worry about a widespread outbreak.
Jamie McDonald / Staff / Getty Images
Remind Me, What Is Bird Flu Again?
Bird flu, or avian influenza, is caused by the influenza A virus subtypes. There are many subtypes, but the highly pathogenic H5N1 strain first emerged in 1996 and has since caused outbreaks worldwide, including in the U.S.
H5N1 affects mostly wild birds and waterfowl, like ducks and geese, but it has also spread to other animals. Since 2022, H5N1 has been detected in more than 100 million chickens in 48 states and 295 dairy cow herds in 14 states, according to the Centers for Disease Control and Protection.
The virus can also spread to humans. People can contract the disease by breathing in viral particles or when the virus gets into their eyes, nose, or mouth after touching an infected animal or surface.
Since April, when it was reported that bird flu infected cows in Texas, there have been 18 confirmed cases of people contracting bird flu, including the case in Missouri. Seventeen became infected from close contact with infected dairy cows and poultry. Just in the past week, the CDC confirmed that three dairy workers in California got the virus from infected cows.
Some people with bird flu experience no or mild symptoms like pink eye or congestion. But bird flu can also cause swelling or irritation in the brain, spinal cord, or nerves, resulting in seizures, coma, or even death. About half of people with H5N1 will die from it, though none of the 18 confirmed cases in the U.S. resulted in death.
What Happened in Missouri?
In late August, a patient (whose identity hasn’t been released) was hospitalized with gastrointestinal issues. After testing positive for influenza type A, the patient’s sample was sent to a state lab for testing as part of a statewide flu surveillance program, where H5N1 was detected. The CDC further tested the sample, which confirmed the presence of bird flu. In the meantime, the patient made a full recovery.
Yet the source of the H5N1 infection has left healthcare experts stumped. “Where the virus came from, nobody has the answer to that,” Richard Webby, PhD, the director of the World Health Organization Collaborating Centre for Studies on the Ecology of Influenza in Animals and Birds, told Health.
Also unusual: While the patient reportedly already had a cough due to an underlying health problem, they did not experience the usual respiratory and other symptoms associated with bird flu.
Whether the patient spread the virus to close contacts is still an open question.
A member of the patient’s household reportedly developed GI symptoms simultaneously but was not tested for bird flu. Several healthcare workers who’d had contact with the patient reported experiencing respiratory symptoms afterward, but most of them didn’t test for bird flu because they reported their illnesses after the 10-day window for testing had passed. The ones that tested had negative results.
The CDC is currently testing samples from the patient and the healthcare workers. Results are expected in mid-October, said Brad Hutton, MPH, a clinical professor at the University of Albany School of Public Health and former deputy commissioner for public health in New York State.
These tests will look for H5N1 antibodies, which could indicate human-to-human transmission from the original patient to the healthcare workers or whether another infection, such as COVID-19, caused the symptoms, Hutton told Health.
How Worried Should You Be?
While person-to-person transmission has happened before, experts say the likelihood of sustained transmission in human populations is very low.
The current strain would have to undergo significant genetic mutations to do so, David A. Schwartz, MD, a medical epidemiologist and board-certified pathologist, told Health. That’s what happened in the past when certain types of influenza A led to pandemics, such as the H1N1 “swine flu” in 2009 and the H1N1 “Spanish flu” in 1918 (which was later determined to be an “avian-like” virus).
But the good news is that “there’s no evidence that H5N1 has undergone any mutation or evolution to be able to pass easily to human beings or to have human-to-human infection,” Schwartz said.
“Having one case like this is not as concerning because [the virus] is not built to spread in communities,” added Don Galbadage, PhD, an associate professor in the Harris College of Nursing & Health Sciences who specializes in epidemiology, microbiology, and public health.
After the recent California cases, the CDC issued a statement saying that “the identification of H5 in people with exposure to infected animals is not unexpected and does not change CDC’s risk assessment for the general public, which continues to be low.”
Still, taking precautions to prevent contracting the disease lessens the opportunity for the virus to spread among people. “It’s probably still very rare,” Webby said, “but every opportunity we give this virus increases the chances that it’s going to make the mutations it needs to transmit from human to human.”
How to Reduce Your Odds of Contracting Bird Flu
There are several ways to decrease your risk of a bird flu infection.
One of the easiest strategies, given that people who work on dairy or poultry farms are at higher risk, is to minimize exposure to animals that can carry it. “Avoid contact with birds, especially if there’s a known outbreak in the area,” Galbadage said.
You should also opt for pasteurized dairy products, which have been through a process that can kill potential pathogens (testing in the spring revealed that some commercial products contained particles of influenza virus fragments, but they were noninfectious). Raw milk and products containing it have not been pasteurized.
The experts also recommend getting vaccinated against seasonal flu. “While it might not address bird flu alone, having that can reduce having two infections at the same time,” Galbadage said.
“Some of this is, to some extent, just decreasing the probability that we have conditions that are favorable to a pandemic,” Hutton said.
This story originally appeared on: Health News - Author:Stephanie Anderson Witmer
