Bird flu is a highly contagious viral disease caused by Influenza Type A viruses which generally affects poultry birds such as chickens and turkeys. There are many strains of the virus – some of them are mild and may merely cause low egg production or other mild symptoms among chickens, while others are fatal.

<strong>How does it bird flu spread?</strong>

Many birds carry the flu without developing sickness, and shed it in their droppings. From water birds, many of whom migrate and travel long distances, the viruses are thus further spread to poultry and terrestrial birds. Sometimes, the virus jumps over to mammals such as pigs, horses, cats and dogs.

<strong>Does it spread to humans?</strong>

Generally, people coming in close contact with infected live or dead birds have contracted the H5N1 bird flu. However, it does not usually spread from person to person, as per the WHO. There is also no evidence that the disease can be spread to people through well cooked poultry food. The virus is sensitive to heat, and dies in cooking temperatures.

<strong>Impact on humans?</strong>

Bird flu outbreaks have been affecting poultry around the globe for decades, and culling of infected birds has been a common measure to contain the spread. But it was in 1997 when humans are first known to have contracted bird flu following an outbreak in a live bird market of Hong Kong. It was the H5N1 strain of the virus, and 6 out of 18 infected humans died of the disease.

Subsequently, several other strains of the virus such as H5N2 and H5N8 are known to have jumped from animals to humans, thus becoming a global public health concern.

<strong>Symptoms and treatment?</strong>

Unlike in birds, where it generally infects the gut, the avian influenza attacks the respiratory tract of humans and may cause severe respiratory illnesses such as pneumonia or Acute Respiratory Distress Syndrome (ARDS). Its early symptoms include fever, cough, sore throat and sometimes abdominal pain and diarrhoea.

Antiviral drugs, especially oseltamivir, improve the prospects of survival in humans, according to the Union health ministry. The ministry advises people working with poultry to use PPEs and follow hand hygiene. In the US, the FDA approved a vaccine for the H5N1 virus in 2007.

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