H5N1 Bird Flu: Should We Concern About the Spread?

Canada reports its first presumptive human case of H5N1 bird flu. The patient is a teenager, currently in critical condition and receiving treatment at British Columbia Children’s Hospital.

Recently, the USA has witnessed an increasing number of H5N1 Bird flu among dairy cattle, poultry, and wild birds. According to the United States of Agriculture (USDA), since March 2024, the outbreak has been reported in 491 dairy farms in 15 states of the US. The virus also infected flocks of chickens, turkeys, and various wild birds.

What is happening?

The USDA reported the first H5N1 (avian influenza A) case in a pig on a farm in Oregon on October 30. According to the CDC (Centers for Disease Control and Prevention), 46 confirmed human cases of Bird flu have been reported across six states in the US since April.

On Saturday Canada reported its first presumptive H5N1 bird flu human case in a teenager raising concerns about the transmission of this deadly virus among various species.

What is the major issue?

The H5N1 variant is a highly pathogenic avian influenza (HPAI) virus with a high mortality rate in infected poultry. ⁽¹⁾ However, the major concern is the identification of clade 2.3.4.4b of the H5N1 virus variant in the pigs. It is the same clade that infected birds, and wild and farm animals in 2020.

Pigs are called genetic mixing vessels because they can be infected by both avian and human flu viruses. Pigs have receptors in their respiratory tracts that can bind to both flu viruses. Above all, if both flu viruses infect them, they can exchange their genetic material and mutate to generate a new hybrid that can be transmitted among human beings.

Past outbreaks

Earlier, outbreaks of HPAI (A) H5N1 were reported in various parts of the world. In February 2023, the virus was first detected in birds in Argentina and in August it was identified in sea lions and later in elephant seals at the beginning of October. The virus killed approximately 17,000 elephant seals and at least 24,000 sea lions in South American countries. ⁽²⁾

Altogether, the evidence of the earlier cases indicates the evolving nature of the virus that infects various wild birds, wild mammals, and, most recently, pigs and humans. ⁽²⁾

What is Avian Influenza type A

Avian influenza or Bird flu mostly spreads in birds but sometimes it can also spread to humans. The avian influenza type A viruses have different subtypes and lineages. The subtypes of the virus are divided based on the presence of hemagglutinin (HA) and neuraminidase(NA) proteins on the surface of the virus. These subtypes can infect birds, humans, poultry, pigs, horses, cats, wild water birds, seals, bats, and dogs. ⁽¹⁾

The Avian influenza type A viruses are categorized into two types:

• LPAI (Low Pathogenicity Avian Influenza A viruses)
• HPAI (Highly Pathogenic Avian Influenza A viruses)

Transmission of the virus

Avian influenza A (Bird flu) transmission from the infected birds to animals is through direct contact. Humans can get the virus through direct contact with the infected bird (saliva, mucous, or feces) or through another animal. ⁽³⁾

Human-to-human transmission of the virus is rare. However, people such as poultry farmers who have direct contact with infected birds and their contaminated environments are more at risk of getting an infection.

Symptoms

Birds

• Sudden death without any initial signs
• Diarrhea
• Coughing and sneezing
• Low energy or appetite
• Nasal discharge
• Drop in the egg production
• Lack of coordination

Animals

• Fever
• Breathing difficulties
• Lethargy
• Death
• Nasal and eye discharge
• Low appetite
• Conjunctivitis

Humans

• Fever
• Body or muscle aches
• Headaches
• Breathing difficulties
• Cough
• Conjunctivitis – Eye irritation, redness and discharge
• Diarrhea
• Stuffy or runny nose
• In severe cases, complications such as pneumonia and acute respiratory syndrome may develop

Diagnosis

Avian influenza A virus infection in humans can be detected by collecting and testing the nasal or throat swabs from the upper respiratory tract of the infected patients. ⁽⁴⁾

Treatment

The CDC recommends antiviral drugs for the treatment of suspected or confirmed H5N1 avian influenza A virus infections. Oseltamivir, peramivir, and zanamivir are the recommended antiviral drugs in the treatment of infected avian influenza A patients. ⁽⁵⁾

Prevention

To prevent the infection of avian influenza (Bird flu)

• Avoid direct contact with the infected or dead poultry, wild birds, and other animals
• Wear PPE (Personal Protective Equipment) while dealing with infected or dead birds and animals
• Avoid touching surfaces or materials that are contaminated with mucus, saliva, and feces of suspected or infected avian influenza A birds and other animals
• Avoid drinking raw milk or milk products from animals with suspected or infected H5N1 influenza A virus.
• Wear protective gloves and masks while handling infected or dead birds and animals

Conclusion

The present situation addresses the evolving nature of H5N1 avian influenza A virus infection in both birds and animals. While cases of human infections are rare, the jumping nature of virus hosts is raising concerns about the risk of human-to-human transmission. Surveillance and early detection of the infection in both domestic and wild birds and animals is crucial to prevent widespread outbreaks. Research, and advancement in antiviral treatments and vaccines are imperative to prevent the threat of future pandemics.

Calls to Action

In the era of witnessing viral infections and diseases, information on these topics is essential to protect oneself from these infections. Share the article and stay informed on the latest medical and healthcare news.

References

1. CDC. Avian Influenza Type A Viruses [Internet]. Avian Influenza (Bird Flu). 2024. Available from: https://www.cdc.gov/bird-flu/about/index.html
2. ‌Plaza PI, Víctor Gamarra-Toledo, Juan Rodríguez Euguí, Rosciano N, Lambertucci SA. Pacific and Atlantic sea lion mortality caused by highly pathogenic Avian Influenza A(H5N1) in South America. Travel Medicine and Infectious Disease. 2024 Mar 1;59:102712–2.
3. CDC. Transmission of Avian Influenza A Viruses Between Animals and People [Internet]. Avian Influenza (Bird Flu). 2024. Available from: https://www.cdc.gov/bird-flu/virus-transmission/index.html
4. ‌CDC. What Causes Bird Flu Virus Infections in Humans [Internet]. Avian Influenza (Bird Flu). 2024. Available from: https://www.cdc.gov/bird-flu/virus-transmission/avian-in-humans.html
5. ‌CDC. Interim Guidance on the Use of Antiviral Medications for Treatment of Human Infections with Novel Influenza A Viruses Associated with Severe Human Disease [Internet]. Avian Influenza (Bird Flu). 2024 [cited 2024 Nov 14]. Available from: https://www.cdc.gov/bird-flu/hcp/novel-av-treatment-guidance/

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