Avian Influenza (Bird flu): Causes, Risk Factors, Symptoms, Treatment

Avian Influenza (Bird flu)

Avian influenza is a viral respiratory disease which is transmitted from poultry/birds to humans. Avian flu was first detected in the state of Maharashtra in India in February 2006. Avian influenza is responsible for multiple outbreaks among poultry which lead to episodes of transmission to humans from poultry. Avian influenza virus survives for long periods of time in moderate temperatures and in water and will survive indefinitely when frozen.

If you develop severe respiratory symptoms, fever, or have a history of exposure to sick birds, seek immediate consultation with an Infectious Disease specialist or a Pulmonologist in the Internal Medicine department to assess the possibility of Avian Influenza (Bird flu).

Causes

There are four types of influenza viruses, namely type A, B, C and D. Highly pathogenic Avian influenza (HPAI), which is also known as bird flu, is a disease caused by infection with the Avian(bird) influenza type A virus. Avian influenza generally affects wild and domestic birds eg. Aquatic and migratory birds. There are sub-types of avian influenza viruses(AIV) which are based on the combination of two proteins namely hemagglutinin (H) and neuraminidase (N). There are a total of 16H sub-types and 9N sub-types. Avian influenza viruses are further classified into 2 types based on their ability to cause disease and death in chickens. I. Low pathogenic Avian influenza (LPAI) sub-types are often asymptomatic(do not have any symptoms) or mildly symptomatic II. High pathogenic Avian influenza (HPAI) causes disease and is often fatal. is also known as bird flu, which is caused by H5N1 and H5N8. Subtypes H5 and H7 of type A, causes major illness in birds which spreads rapidly and leads to high death rates among different species of birds. Influenza virus A sub-types H5, H6, H7, H9 and H10 are known to cause infection in humans.

Risk Factors

Ø Individuals who work in close contact with sick birds eg. Slaughter house workers, poultry farmers. Ø Individuals who handle infected birds or dead birds due to infection are at high risk of acquiring infection. Ø Pregnant women Ø Children Ø Individuals with decreased immune system are are high risk for acquiring avian influenza virus easily when comes into contact with the infected birds or individuals. Ø The most common way for the virus to spread from one region to another is through migratory wild birds i.e. when the infected birds travel from one place to another place during seasonal changes. Ø When humans come into direct or indirect contact with infected animals or birds , the environment or the surface is contaminated by the feces of the infected birds, the virus transmits to humans. Ø The Influenza viruses also spreads rapidly through equipment used, vehicles, egg crates ,human clothing, shoes, water. Ø The virus can be inhaled from droplets or dust present in the environment, but this is rare.

Symptoms

Ø Although birds are normally resistant to these viruses, birds carry these viruses in their respiratory tract and intestines and drop them through their saliva, nasal secretions and feces into the surroundings, thereby infecting the domestic birds. The disease spreads from one place to another by migratory words. Ø Both HPAI and LPAI can cause infection in humans Ø Symptoms range from mild illnesses to fatal conditions. It takes 3-5 days for the symptoms to appear after being exposed to the virus. The usual symptoms include: l Fever l Sore throat l Cough l Runny nose or stuffy nose l Headache l Muscle and body aches l nausea l vomiting l Diarrhoea l Chest pain l Conjunctivitis (also called as pink eye as it causes the eyes to become red and swollen) l Bleeding from nose and gums In some cases, the virus spreads rapidly and causes l Shortness of breath l Avian influenza virus also causes secondary bacterial infections l Pneumonia l Seizures l Respiratory distress (a life-threatening lung injury which causes fluid to leak into the lungs and it becomes harder to breath and fast breathing) l Respiratory failure (in which condition, patient might be kept on a mechanical ventilator) l Multi-organ failure l Septic shock

Diagnosis

Bird flu/avian influenza cannot be diagnosed with clinical signs and symptoms alone Laboratory tests play a crucial role in diagnosing bird flu/avian influenza. Nose swab or throat swab molecular testing would be helpful in early detection of influenza virus and prevent the complications.

Treatments

Seeking treatment in the early stages of infection of avian influenza virus would be helpful as it reduces the complications. The treatment of bird flu or avian influenza virus generally includes antiviral medications like oseltamivir or zanamivir or other anti-viral medications. The health care provider will decide the dose, frequency and duration of medication based upon the age and co-morbidities (other existing diseases or conditions eg. Hypertension(high blood pressure); diabetes, thyroid issues, asthma etc.) These medications help in reducing the severity of the condition and helps prevent the complications

Preventive Measures

Ø Wear gloves and wash your hands before and after handling sick or dead birds. Ø When travelling to a country or region , with a recent outbreak of bird flu/avian influenza virus, restrict yourself from visiting poultry farms. Ø Quadrivalent influenza vaccine can be taken by all the individuals aged 6months and older. It provides protection against flu viruses, which include two influenza A viruses and two influenza B viruses.

Do's & Don’t's

Do's Don't 
Take medications as prescribed.  Keep birds that are sick or dead.
Keep yourself well hydrated.  Neglect proper disinfection of equipment and vehicles used for sick birds.
Wash hands properly and often to prevent infection.  Disregard the disposal of gloves and masks used when handling sick or dead birds.
Cook meat thoroughly at high temperatures. Allow sick or dead birds to remain in proximity.
Wear gloves and a mask when handling sick birds. Handle sick birds without wearing gloves and a mask, as direct contact may increase the risk of contracting or spreading avian influenza.
Dispose of gloves and masks properly. Neglect to wear gloves and a mask when handling sick birds, as direct contact without protective gear can increase the risk of transmission of avian influenza and other potential infections.
Frequently Asked Questions
Avian influenza, also known as bird flu, is a viral infection that primarily affects birds. It can occur in wild birds as well as domestic poultry like chickens, ducks, and turkeys. Several strains of avian influenza viruses can cause illness in birds.
Avian influenza spreads among birds through direct contact with infected birds or their droppings. It can also spread through contaminated surfaces, equipment, or environments. Some strains can be transmitted from birds to humans, usually through close contact with infected birds or their excretions.
Yes, although it's rare, some strains of avian influenza can infect humans. The risk is higher for people who work closely with infected birds or handle them. Human infections are typically associated with direct exposure to infected birds or surfaces contaminated with their droppings or respiratory secretions.
Symptoms in humans can range from mild to severe and may include fever, cough, sore throat, muscle aches, difficulty breathing, pneumonia, and in severe cases, respiratory failure and death.
Diagnosis involves laboratory tests on samples collected from an individual suspected of being infected with avian influenza. These samples could include swabs from the respiratory tract, blood tests, or other bodily fluids.
Antiviral medications may be prescribed for severe cases of avian influenza in humans. However, the effectiveness of these treatments can vary depending on the strain of the virus and the individual's health condition.
Human-to-human transmission of avian influenza is uncommon. However, in some cases, limited human-to-human transmission has occurred, especially within close contacts of infected individuals. Such instances are closely monitored by health authorities to prevent further spread.
Controlling avian influenza in birds involves measures such as quarantining infected flocks, culling affected birds to prevent the spread, enhancing biosecurity measures in poultry farms, and proper disposal of infected birds or carcasses.
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