Some background on bird flu There are two types of avian influenza: highly pathogenic or low pathogenic, based on the level of disease the strain causes in birds.
H5N1 first emerged in 1997 in Hong Kong and then China in 2003, spreading through wild bird migration and poultry trading.
In the past, outbreaks could be controlled by culling of infected birds, and H5N1 would die down for a while.
Read more: When should we worry about bird flu making us sick?
Globally, there have been 14 cases of H5N1 clade 2.3.4.4b virus in humans, and 889 H5N1 human cases overall since 2003.
Avian flu viruses don’t easily spread in humans.
But it’s no longer feasible to control an outbreak by culling infected birds, so some countries like France began vaccinating poultry in 2023.
The 2009 flu pandemic started in May in Australia, but the vaccines were available in September, after the pandemic peak.
After the first case of H5N1 avian influenza, also known as bird flu, appeared to spread from a cow to a human, the Centers for Disease Control and Prevention (CDC) in the United States have released a health alert.
The virus was spread by a farm worker in Texas during a dairy cattle outbreak. In Colorado in 2022, a poultry worker tested positive, making this the second human case in the US.
Since the virus strain found in the Texan farm worker is not easily spread among people, there is no risk of a pandemic. Still, it’s a noteworthy development.
An overview of bird flu history.
Based on the degree of illness the strain infects birds, avian influenza can be classified as highly pathogenic or low pathogenic. The avian influenza strain H5N1 is extremely dangerous.
H5N1 first appeared in 1997 in Hong Kong, and in 2003 it moved to China as a result of poultry trading and wild bird migration. In addition to sporadic human cases, it has periodically caused epidemics in chicken farms.
Variants of influenza A viruses, such as H5N1, are further classified into groups known as clades. H5N1 clade 2.3 is the distinct variant responsible for the ongoing pandemic. The late 2020s saw the emergence of 4.4b, which is currently widely used worldwide, particularly in the Americas.
Previously, outbreaks could be contained by eliminating infected birds, which would cause the H5N1 virus to temporarily disappear. However, since 2021, as outbreaks have increased, this has grown more challenging.
Read more: Human-to-human transmission—which, as of yet, lacks evidence—is when we should be concerned that bird flu could infect humans.
The mix now includes wild animals.
Since waterfowl migrate through specific routes that avoid Australia, they are the primary global spreaders of avian flu. This includes ducks, swans, and geese. China’s Quinghai Lake serves as the primary hub for waterfowl migration worldwide.
However, raptors and other non-waterfowl birds that use distinct flyways, like true thrushes, are becoming more and more infected. Furthermore, Australia is now vulnerable to various bird species that fly here due to the worrying spread of the infection to Antarctica.
Since 2021, the H5N1 virus has spread in an unprecedented way, infecting an increasing number of mammals worldwide, including domestic dogs, cats, goats, red foxes, sea lions, and coyotes.
Peri-urban wild animals, such as red foxes, may find a new way to spread to domestic pets, farms, and people.
At least 17 farms in seven US states currently have at least 17 cases of H5N1 infection in their dairy goats and cows.
What signs and symptoms are there?
There have been 14 H5N1 clade 2.3 cases reported worldwide. Humans have contracted the 4.4b virus, and since 2003, there have been 889 cases of H5N1.
A severe respiratory illness has been observed in previous human cases, however H5N1 2.3. Diseases related to 4.4b are also impacting the liver, brain, and eyes.
Recent cases, for instance, have experienced neurological side effects such as organ failure, stroke, and seizures. About half of those with H5N1 infection are expected to pass away.
The Texan farm worker’s case seems to be straightforward. It is unusual that this person presented with conjunctivitis.
food security.
One of the main risk factors for human infection is contact with sick poultry. Similarly, it’s probable that the Texas farm worker had close contact with the contaminated cattle.
According to the CDC, eggs that are well cooked and pasteurized are safe options. On the other hand, consuming unpasteurized milk or handling contaminated meat or eggs while cooking could be dangerous.
Hygienic food practices are always a good idea, even though there is no H5N1 in Australian cattle or poultry. This is because microbes like salmonella and E Coli can infect raw milk, poorly cooked meat, eggs, or poultry.
Why are we concerned if this isn’t a pandemic?
Since roughly2005, scientists have been concerned that avian influenza could start a pandemic. In humans, avian flu viruses are not easily transmissible. Pandemics, however, can occur if an avian virus mutates and spreads to people.
This serves as a genetic mixing vessel, which is a concern if birds were to infect an animal such as a pig. The likelihood of human and bird flu strains mixing and mutating to create a new pandemic strain is higher in places where people and livestock are in close proximity, such as farms, markets, or even homes with backyard chickens.
Farmers discovered their infected Texas cows were giving less milk, so they tested them. If the disease affects beef cattle as well, it might be harder to detect and farmers might be discouraged from testing for or reporting infections due to the financial loss.
In what way can a pandemic be avoided?
There isn’t currently a direct threat of a pandemic because H5N1 isn’t spreading among people.
However, H5N1 clade 2.3 infection is currently unprecedented and persistent. More wild animals, farms, and a greater variety of wild birds than ever before have 4.4b, increasing the likelihood that H5N1 will mutate and start a pandemic.
The new hot spots (and most likely places of pandemic emergence) are in the Americas, Europe, or Africa, in contrast to the prior avian flu epidemiology, which had hot spots in Asia.
Early warnings of animal and human outbreaks are critical because pandemics spread rapidly. Surveillance tools like our EPIWATCH platform allow us to keep an eye on infections.
The greater the opportunity of quickly creating vaccines and eradicating epidemics, the earlier they can be identified.
Although there is a vaccine for birds, it has not been widely used until recently due to its limited effectiveness and potential to conceal outbreaks. However, eliminating sick birds is no longer a practical way to contain an outbreak, which is why some nations, like France, started immunizing poultry in 2023.
See also: Birds that are vulnerable in Australia may contract deadly avian flu from migrating birds.
Seasonal flu shots for humans may offer some cross-protection, but the optimal protection comes from vaccines that are precisely matched to the pandemic strain, which requires time. In Australia, the 2009 flu pandemic began in May, but vaccinations weren’t made available until September, after the pandemic peaked.
We need to understand how H5N1 is spreading to so many different mammalian species, what new wild bird pathways are at risk, and how to keep an eye out for early indicators of outbreaks and illness in animals, birds, and people in order to lower the likelihood of a pandemic. Assuring that we identify every outbreak and prevent the food supply from being jeopardized requires financial support for farmers.
