Viruses

Avian Flu or Bird Flu & What You Need To Know

Author Chandana Balasubramanian , 18-01-2022

New strains of the avian flu virus are causing havoc across Europe and Asia. Because of the number of variants, experts believe there is a greater risk of transmission to humans. According to the OIE (World Organisation for Animal Health), over 40 countries reported bird flu outbreaks. The OIE noted that an “unprecedented genetic variability of subtypes” was spreading across the world [1]. Though infections in humans are rare, the UK just reported a 79-year-old retired train driver to be the first human to test positive for one of the new variants. Fortunately, the gentleman reported no symptoms of the illness, and his latest test turned out negative [2].

 

Avian influenza, commonly known as bird flu, is a viral respiratory illness that spreads quickly between birds and causes severe death and disease in poultry and some animals. It is caused by influenza viruses and can be lethal in humans. Within a region, the flu can be transmitted through bird saliva and other secretions. It is also spread by airborne feces-contaminated dust and soil, bird feed, or wild animals. Humans in close contact with infected birds can also spread the virus to birds through the dirt under their shoes or contaminated clothing. Markets that sell or keep live poultry are also more likely to spread the disease [3].

 

In winters, bird flu can spread across the globe when infected birds migrate to warmer regions to escape the cold weather. The country of Israel is currently battling a severe bird flu outbreak that resulted in the deaths of thousands of migratory wild cranes and half a million chickens [4]. The country happens to be located at a critical point in one of the world’s biggest migration routes for birds. The UK is also experiencing a record-high number of bird flu cases; more than half a million birds have been culled [5]. The southern state of Kerala in India experienced a large outbreak late last year. Thousands of ducks and local birds died or were killed to prevent further spread. Visiting migratory birds are believed to be the source. The international poultry trade is another way for avian influenza to spread across regions [6].

 

Avian flu outbreaks are of global concern because some subtypes of the virus are highly contagious. Even if the current outbreaks do not end up infecting many humans, the mass culling of infected birds can negatively impact regional sources of food and livelihood. Additionally, because avian influenza has the potential to cause severe illness and even death in humans, there is always a concern that the virus may be used as an agent of bioterrorism [7]. Avian influenza history has also been filled with outbreaks and cases as well.

What Causes Avian Flu, also known as Bird Flu Virus?

 

Avian flu is caused by avian influenza A viruses that primarily affect birds. They are members of the Orthomyxoviridae family of viruses. Ducks, geese, swans, and other waterfowl are usually the primary hosts. Feces from an infected bird can spread the disease to other birds.

Apart from birds, cats, dogs, pigs, and horses have been known to contract the avian flu, but the risk is very low [3].

There are two types of the bird flu virus:

  •   Low pathogenicity avian influenza (LPAI): which causes only mild symptoms of the disease, and
  •   Highly pathogenic avian influenza (HPAI): meaning it can cause severe illness or symptoms and even death. HPAI is also known as the ‘fowl plague.’

The more virulent forms are believed to be mutations of the milder versions.

How Does Pathogenic Avian Influenza Affect Humans?

 

Though rare, the avian flu can spread to humans. Once infected, a human cannot transmit the virus easily to another person. Most people infected by the avian influenza virus have had prolonged close contact with infected birds. They either breathe in droplets of air or touch their mouths, eyes, or nose after touching surfaces with the virus on them.

Though infections in humans are rare, avian influenza viruses can cause deaths. For this reason, outbreaks are closely monitored. There is also a risk of a new mutation being highly transmissible among humans, leading to a future pandemic.

Specific variants of the avian influenza virus, such as H5N1, H7N9, H5N6, H5N8, and newer strains, are causes of concern. H7N9 does not affect birds but infects humans. H5N1 is of particular interest based on the number of outbreaks it triggers, including the recent 2021-2022 wave [8].

The avian flu can be deadly, but timely medical intervention can help minimize the severity and prevent deaths.

Can You Get Bird Flu from Cooked Birds like Chicken or Eggs?

 

According to the CDC, it is safe to eat cooked poultry or eggs if prepared hygienically and cooked thoroughly. Food safety guidelines must be followed when handling raw poultry to prevent salmonella and other infections. 

In the United States, if you work with live chickens, you will need to follow USDA food safety guidelines.

 

History of Avian Flu in Humans

 

According to the GIDEON database of infectious diseases, the first recorded cases of bird flu in humans were from Hong Kong in 1997. There were 18 cases, of which six were fatal. From 2003 to 2016, the World Health Organization (WHO) recorded 850 infections from the H5N1 bird flu subtype.

This number may not seem high compared to other diseases, but more than half of the infected individuals died. The majority of human deaths from the bird flu during this time were recorded in Egypt, Indonesia, and Vietnam.

In 2003, thousands of chickens were culled in the Netherlands during an avian influenza outbreak by an H7N7 strain. One human death was reported. In 2013, dozens of H7N7-related human deaths were recorded in China. In the Americas, the first human infection with HPAI H5N1 was in Canada in 2014. 

 

Symptoms of an Avian Influenza Virus Infection

 

According to the CDC, symptoms can range from mild to severe. They include:

  • Conjunctivitis
  • Flu-like symptoms (fever, headache, cough, nasal congestion, sore throat, muscle pain)
  • Occasionally, nausea, vomiting, diarrhea, severe respiratory illness, pneumonia, and even multi-organ failure in severe cases.  

Symptoms can persist for up to two weeks, but most last two to seven days.

Diagnosis

 

Since avian flu symptoms can be similar to that of other influenza viruses, and some patients may present with co-infections like pneumonia, lab testing is required for accurate diagnosis. According to the CDC, tests are more accurate if tissue samples are collected within the first few days of illness.

WHO recommends an RT-PCR (reverse transcriptase-polymerase chain reaction) test or a real-time reverse transcriptase PCR assay. Other tests used are rapid antigen tests.

Treatment

 

Avian influenza in humans can turn into a severe illness and must be treated in a hospital. WHO notes that the antiviral medicine, Oseltamivir, can reduce disease severity and prevent death. Zanamivir, delivered through an inhaler, can also be an alternative. In recent times, oseltamivir resistance has been detected.

Prevention

 

There is no commercially available vaccine for the bird flu. In 2007, the US FDA approved a vaccine to protect humans against one type of H5N1 virus. It can be used in adults (18-64 years of age) at increased risk of exposure to the H5N1 virus. The US Federal Government stockpiled this vaccine in the event of rapid human-to-human transmission.

The CDC notes that the best prevention is to avoid sources of exposure. Frequent hand washing with warm water and soap is recommended before and after handling raw poultry. You may also use separate utensils for raw meat. Ensure you cook your chickens and eggs thoroughly before eating and avoid contact with wild birds and poultry. If it is your job to work with wild birds or poultry, wear protective gear and ensure you clean your hands before touching your eyes, nose, or mouth [9].

One of the biggest challenges in developing a bird flu vaccine, even for birds, is many different varieties of the avian influenza virus. There are also new mutations and strains of the virus to continue tackling, like with the human flu.

The bottom line is that there is no need to panic about a bird flu epidemic or pandemic in humans. The risk of transmission to humans and between humans is still very low. However, public health officials and researchers must remain vigilant and track the raging bird flu outbreaks occurring across the world to protect our wildlife and poultry. More data-driven studies are required to determine levels of risk to birds, animals, and humans. Researchers may use comprehensive platforms like the GIDEON infectious disease database for unified data on infectious diseases.  

References
[1]OIE: The World Organisation for Animal Health, “The World Organisation for Animal Health (OIE) calls for increased surveillance of avian influenza as outbreaks in poultry and wild birds intensify,” OIE, 19 November 2021. [Online] [Accessed 11 01 2021].
[2]R. McGuinness, “Bird flu ‘patient zero’ tests negative for virus – and plans to get more ducks,” Yahoo News, 10 01 2021. [Online][Accessed 11 01 2021].
[3]CDC: Centers for Disease Control and Prevention, “Information on Avian Influenza,” CDC, 21 03 2019. [Online][Accessed 11 01 2021].
[4]D. F. Maron, “Deadly bird flu threatens Israel’s wildlife, triggers hunting ban,” National Geographic, 10 01 2021. [Online][Accessed 11 01 2021].
[5]Department for Environment, Food & Rural Affairs and Animal and Plant Health Agency, “Guidance: Avian influenza (bird flu),” GOV.UK, 11 01 2021. [Online][Accessed 11 01 2021].
[6]The Hindu, “Bird flu in Kerala: T.N. ramps up surveillance,” The Hindu, 04 01 2021. [Online] [Accessed 11 01 2021].
[7]M. M. M. D. Tatyana Novossiolova, “The Creation of a Contagious H5N1 Influenza Virus: Implications for the Education of Life Scientists,” J Terror Res, vol. 3, no. 1, pp. 39-51, 2021.
[8]CDC: Centers for Disease Control and Prevention, “Highly Pathogenic Asian Avian Influenza A(H5N1) in People,” CDC, 18 03 2015. [Online] [Accessed 11 01 2021].
[9]CDC: Centers for Disease Control and Prevention, “Prevention and Treatment of Avian Influenza A Viruses in People,” CDC, 17 04 2017. [Online] [Accessed 11 01 2021].
Author
Chandana Balasubramanian

Chandana Balasubramanian is an experienced healthcare executive who writes on the intersection of healthcare and technology. She is the President of Global Insight Advisory Network, and has a Masters degree in Biomedical Engineering from the University of Wisconsin-Madison, USA.

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