US authorities said that H5N1 avian influenza A (bird flu) virus (HPAI H5N1) is still a low risk to humans. Health experts believe that current treatment and vaccines, as well as those in the pipeline, can effectively prevent severe disease.
The National Institutes of Health (NIH) and other American health and research departments, however, are closely monitoring the virus and evaluating the potential threat of any changes, say leading officials at the National Institute of Allergy and Infectious Diseases (NIAID), which is part of the NIH.
Michael G. Ison, M.D., M.S., and Jeanne M. Marrazzo, M.D., M.P.H., both from NIAID, emphasize the need to balance ‘business as usual’ with ‘enhanced vigilance’ regarding HPAI H5N1.
They shared their findings and opinions in the prestigious New England Journal of Medicine (citation below).
Bird Flu – Brief Background
For nearly thirty years, HPAI H5N1 influenza viruses have circulated in 23+ countries. Towards the end of 2021, HPAI H5N1 reached North America from Europe, causing occasional infections in poultry farms and among wild birds.
In 2022, the virus made its way down to Mexico and then South America, where it devastated birds and marine mammals, such as sea lions, fur seals, and dolphins.
Scientists at the United States Department of Agriculture (USDA) identified HPAI H5N1 in American dairy cows in March 2024. During that year, herds in 16 states became infected.
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What is Bird Flu?
The Cleveland Clinic has the following description of Bird Flu (Avian Influenza):
“Avian influenza, commonly called “bird flu,” is a viral infection that spreads in birds, cows and other animals. It can sometimes spread to people. In humans, H5 subtypes of influenza A are the most common cause.”
“It can cause mild to severe respiratory symptoms and pink eye. People who work with poultry, waterfowl, and dairy cows are most at risk.”
Suspected Human Cases of Bird Flu
In the last 30 days, the virus has been found in dairy herds across three U.S. states, according to USDA/APHIS.
So far in 2024, there have been 66 confirmed and 7 suspected human cases of bird flu in the U.S., as well as one case in Canada.
These infections were caused by two types of the virus: one primarily affecting birds (D1.1) and another linked to dairy cows (B3.13).
Controlling the Outbreak
Drs. Ison and Marrazo say the following are key to controlling and combating the current bird flu outbreak:
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Collaboration
Timely and effective collaboration among researchers in public health, healthcare, veterinary and human medicine, as well as occupational workers, is crucial. Examples of occupational workers include those employed in dairy and poultry farming.
It is important to cultivate trust between all collaborating entities as well as with individuals who seek care for signs and symptoms of concern, such as conjunctivitis, fever, or respiratory problems, the authors added.
Fortunately, most HPAI H5N1 cases in the U.S. to date have been mild and resolved without the need for medical treatment.
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Vigilant Disease Surveillance
Another key point is the Canadian HPAI H5N1 patient, who developed respiratory failure and required life-saving medical intervention and treatment before recovering.
This patient’s mutated virus highlights the urgent need for close monitoring of the disease to identify and assess viral changes and determine whether there have been any alterations in human-to-human transmission.
For surveillance to be effective, it is necessary to ensure that complete genomic sequencing data from both animals and humans are made available quickly and easily.
If we don’t know where and when the virus samples were collected, it is difficult to connect them to other samples. This makes it harder to understand how the virus is spreading, the authors explained.
This data could help detect changes in the virus early, especially ones that make it more likely to infect human lungs. Sometimes, just one small virus mutation is enough to make this happen.
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Medical Countermeasures
Research centers and pharmaceutical companies must continue to develop and test vaccines, medications, and other therapies that eliminate or alleviate disease against influenza viruses, including bird flu or H5N1.
Current vaccines are effective at neutralizing circulating strains of the bird flu virus, which remain susceptible to antiviral medications. These medications help reduce the spread of the virus and lessen the severity of illness, the researchers wrote.
Exposure and Infection Risk
We must take measures to avoid exposure to the virus and lower the risk of infection. For instance, if you work with poultry and/or cows, you should wear personal protective equipment and stay informed about the risks associated with handling birds and mammals.
If we all follow these four steps, researchers and public health officials investigating HPAI H5N1 will be better positioned to answer many unanswered questions more easily and effectively. Particularly, questions regarding how the bird flu virus spreads, evolves, and affects birds, people, and other mammals.
Citation
M Ison and J Marrazzo. The Emerging Threat of H5N1 to Human Health. NEJM DOI: 10.1056/NEJMe2416323 (2024).