- Avian flu, or bird flu, is increasingly worrying public health experts.
- The H5N1 avian influenza virus is evolving, getting closer to humans and offering more possibilities for adaptation.
- A bird flu pandemic is not inevitable, but it is possible. Here’s why you should know what’s going on.
Avian flu is on the rise and it worries many infectious disease experts more than ever.
The H5N1 avian flu virus has killed tens of millions of birds across the planet and more than 40,000 sea lions and seals. For animals, it’s a pandemic.
Still, the CDC says the risk to humans is low. Most people seem to have little or no chance of catching H5N1 bird flu at this time.
In the United States, only three people have tested positive for the virus since its surprising appearance in the cattle population, and all of them had direct contact with infected cows.
But infectious disease experts are increasingly concerned that the H5N1 virus could make a lasting spread in humans and start spreading among us. This is not inevitable, but several recent developments suggest that it is a growing threat.
“There’s a lot going on,” Dr. Monica Gandhi, professor of medicine and deputy chief of the Division of HIV, Infectious Diseases and Global Medicine at the University of California, San Francisco, told Business Insider. “I’m getting more and more worried.”
You shouldn’t panic, but you should probably know what’s going on. This virus is a leading candidate for the next pandemic, and four developments over the past month have experts worried.
Here’s what you need to know.
Bird flu hospitalizes child in Australia
On Friday, the World Health Organization announced that a 2-year-old child had become Australia’s first human case of H5N1 in March.
Returning from a trip to Calcutta, India, the child’s symptoms – loss of appetite, fever, cough, vomiting and irritability, according to the WHO – hospitalized him for two and a half weeks, including l admission to the intensive care unit.
As human cases appear in different parts of the world, epidemiologists like Christopher Dye are becoming increasingly concerned.
“There are so many viruses out there right now. And it’s clear that they are changing and doing new and unexpected things,” Dye, a professor and senior researcher at the University of Oxford, told BI.
He recently co-authored a paper published in the medical journal BMJ, saying the risk of a major human outbreak is “significant, plausible and imminent.”
“Influenza has always been a concern for decades and decades, and this particular form of influenza for at least two decades,” Dye said. “But now it has reached a level of concern, I think, that is greater than ever before.”
Mice could bring bird flu into homes
A total of 47 house mice tested positive for H5N1 in New Mexico, the U.S. Department of Agriculture reported Tuesday.
“Mice are just about everywhere,” Gandhi said. “They’re around other animals, they’re often around humans. And that’s a little worrying.”
The samples were taken from the sick mice in early May. According to The Telegraph, scientists suspect that mice, as well as some domestic cats, could have contracted the virus by drinking raw milk from infected cows. (Public health experts strongly advise people not to drink unpasteurized, i.e. “raw,” milk.)
“It brings the virus closer to human homes,” Rick Bright, former director of the Biomedical Advanced Research and Development Authority, told the Telegraph. “It’s out of control,” he added.
Each new animal population and each new exposure to humans presents a new opportunity for the virus to mutate and adapt.
Mutation suggests virus has started to adapt
When the CDC analyzed a virus sample from the second infected U.S. farm worker, they spotted a mutation in the virus’s replication machinery — the way it enters its host’s cells to copy itself.
This is a change “associated with viral adaptation to mammalian hosts,” the CDC said in a statement in May. The release also said that studies in mice indicate that this type of genetic mutation of the virus is associated with more severe disease and enhanced viral replication.
This does not make it a human virus.
Aside from this one change, H5N1 has mostly “properties of an avian virus and not a human virus,” Richard Webby, a virologist at St. Jude and director of the WHO Collaborating Center for H5N1 Studies, told BI. ecology of influenza in animals and birds. .
This means the virus is best adapted to thrive and spread among birds, not humans.
However, this could change.
Latest US case presented with worrying cough
The first two farmworkers to test positive for H5N1 in the United States had pink eyes. But the third case, reported in Michigan in May, involved a cough and sore throat.
This means that H5N1 was in this worker’s respiratory system, which is a scarier place to detect a threatening virus than in our eyes.
For one thing, it’s easier to spread a virus by coughing or sneezing than by sharing eye fluid.
The good news is that, according to scientists, H5N1 is not yet sufficiently adapted to humans to transmit between us. The CDC reported no evidence that the coughing farmworker transmitted the virus to anyone else.
But that doesn’t mean H5N1 can’t mutate to transmit from human to human – which brings us to the second sad reality of this farm worker’s respiratory infection.
According to Webby, compared to the eyes, human lungs are a more convenient place for an avian virus to spread further among mammals. In the lungs, the virus is exposed to more cellular receptors that a mammalian virus would bind to, giving H5N1 more opportunities to mutate and begin latching onto these receptors, becoming better adapted to infection and spread between humans.
Many experts worry that the USDA and CDC are not monitoring livestock and farmworkers enough to detect concerns. early mutations and that other human cases could go unnoticed.
“I think there’s enough of a threat here to be very vigilant so that we have a surveillance system in place that as soon as it happens, we can find it,” Dye said.
Vaccines are in preparation
The good news is that bird flu is not COVID-19. Scientists have been tracking this virus and its entire viral family tree, watching for any signs of a growing threat to humans, for decades.
As a result, key elements of a vaccine are already on hold. The United States begins manufacturing millions of vaccines using “candidate viruses” – weakened flu viruses – developed by the CDC.
Although the vaccine candidates do not necessarily match the H5N1 virus perfectly and the use of eggs for vaccines may pose a hurdle to manufacturing if avian flu ravages the chicken population, they may provide some immunity in the event of an outbreak. human epidemic.
Additionally, scientists now have proven mRNA vaccine technology. Vaccines that use mRNA, of which COVID-19 vaccines were the first to be approved, are more flexible and faster to develop than traditional vaccines – and they don’t require eggs.
Researchers at the University of Pennsylvania have already developed an experimental mRNA vaccine against H5N1, which they successfully completed. tested on mice and ferrets.
If H5N1 becomes a problem in humans, a vaccine may be available along with the flu vaccine you will receive later this year.
In the meantime, bird flu poses an imminent threat to watch out for.
“From what I can see, it’s not going away anytime soon,” Dye said.