Bird Flu Virus: Symptoms, Causes, and Risk Factors


Overview Bird Flu Virus

Bird flu virus or Avian influenza do not normally infect humans. However, sporadic human infections with avian flu viruses have occurred. Avian influenza refers to the disease caused by infection with avian (bird) influenza flu Type A viruses.
These viruses occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species.
Influenza viruses type A, B and C are among the causes of respiratory tract infections in humans. Type A virus has 15 sub-types some of which are predominant in pigs (swine influenza virus), in humans (human influenza virus), in horses (equine influenza virus) or in birds (avian influenza virus).  According to the World Health Organization, H5N1 was first discovered in humans in 1997 and has killed nearly 60% of those infected.
Currently, the virus isn’t known to spread via human-to-human contact. Still, some experts worry that H5N1 may pose a risk of becoming a pandemic threat to humans.

Human and animals can pass influenza virus from one to another. Humans can thus, become sick from avian or swine influenza when they pick up the virus from these animals.

In irregular intervals which can be as frequent as yearly, genetic particles of viruses from birds and pigs or humans are mixed (assortment) to produce novel subtypes with increasing virulence. The theory of the pandemic flu is derived from the expectation that such a mixture of viral materials will produce a novel influenza that will spread early in humans unhindered by a non-existent human immunity.

Influenza viruses type

Influenza A viruses are classified into subtypes based on two surface proteins, the hemagglutinin (HA) and neuraminidase (NA). A virus that has a type 1 HA and type 2 NA, for example, would have the subtype H1N2. At least 16 types of hemagglutinins (H1 to H16), and 9 neuraminidases (N1 to N9) are known to exist in birds

Symptoms of bird flu virus

You may have an H5N1 infection if you experience typical flu-like symptoms such as:
If you’re exposed to bird flu, you should notify staff before you arrive at the doctor’s office or hospital. Alerting them ahead of time will allow them to take precautions to protect staff and other patients before caring for you.

Causes bird flu virus

Although there are several types of bird flu, H5N1 was the first avian influenza virus to infect humans. The first infection occurred in Hong Kong in 1997. The outbreak was linked to handling infected poultry.

H5N1 occurs naturally in wild waterfowl, but it can spread easily to domestic poultry. The disease is transmitted to humans through contact with infected bird feces, nasal secretions, or secretions from the mouth or eyes.
Consuming properly cooked poultry or eggs from infected birds doesn’t transmit the bird flu, but eggs should never be served runny. Meat is considered safe if it has been cooked to an internal temperature of 165ºF (73.9ºC).

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What are bird flu virus risk factors

H5N1 has the ability to survive for extended periods of time. Birds infected with H5N1 continue to release the virus in feces and saliva for as long as 10 days. Touching contaminated surfaces can spread the infection.
You may have a greater risk of contracting H5N1 if you are:
  • a poultry farmer
  • a traveler visiting affected areas
  • exposed to infected birds
  • someone who eats under-cooked poultry or eggs
  • a healthcare worker caring for infected patients
  • a household member of an infected person

How is bird flu virus diagnosed?

The Centers for Disease Control and Prevention (CDC) has approved a test designed to identify avian influenza. The test is called influenza A/H5 (Asian lineage) virus real-time RT-PCR primer and probe set. It can offer preliminary results in only four hours. However, the test isn’t widely available.
Your doctor may also perform the following tests to look for the presence of the virus that causes bird flu:
  • auscultation (a test that detects abnormal breath sounds)
  • white blood cell differential
  • naso-pharyngeal culture
  • chest X-ray

Treatment for bird flu virus

Different types of bird flu can cause different symptoms. As a result, treatments may vary.

In most cases, treatment with antiviral medication such as oseltamivir (Tamiflu) or zanamivir (Relenza) can help reduce the severity of the disease. However, the medication must be taken within 48 hours after symptoms first appear.

The virus that causes the human form of the flu can develop resistance to the two most common forms of antiviral medications, amantadine and rimantadine (Flumadine). These medications shouldn’t be used to treat the disease.

Your family or others in close contact with you might also be prescribed antivirals as a preventive measure, even if they aren’t sick. You’ll be placed in isolation to avoid spreading the virus to others.

Bird Flu Virus Prevention and Control:

Prevention and control strategies for Avian Influenza include the following:

In Humans


Taking annual seasonal influenza vaccination is recommended to protect against seasonal influenza virus. This might not protect against any new strain.

Infection prevention practices

  • Those responding to or working with poultry should wearing personal protective equipment while working in communities with existing outbreak.
  • Eat well cooked poultry and poultry products.
  • Practice good hand hygiene

Public Education

  • Include self-monitoring for illness during and after responding to HPAI outbreaks among poultry.
  • Increase surveillance
  • Engender societal behavioral changes

In Poultry farms

  • Disinfection
  • Vaccination of birds

Infection prevention practices

  • Culling infected poultry farm birds
  • Proper disposal of death birds.


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