In recent days, bird flu has been reported in many Indian states.
Also known as avian influenza, this flu has been detected in wild geese in the Himachal Pradesh, crows in Rajasthan and Madhya Pradesh and ducks in Kerala, according to The Indian Express.
The Indian authorities have issued a bird flu alert in several states due to large numbers of birds suddenly dying. In the last few days, around one lakh poultry birds have died in Haryana.
So, what is avian influenza or bird flu?
It is a highly contagious viral disease. The disease is caused by Influenza type A viruses which normally affects poultry birds such as chickens and turkeys.
This virus has many strains. Some strains are mild and can only affect egg production. While some other strains are severe and lethal.
How does the virus spread?
Ducks, geese – mostly wild aquatic birds are the natural reservoir of influenza A viruses. They are also the central players in the ecology of these viruses.
Many of the affected birds don't develop sickness and shed it in their droppings. As birds can defecate while flying, they can shed it all over the place, which makes it even more dangerous.
Can the flu infect humans?
In 1997, humans are first known to have contracted bird flu after an outbreak occurred in a live bird market of Hong Kong. The strain of the virus was H5N1 strain of the virus and it was deadly enough to kill 6 out of 18 infected humans.
Even after it was contained, it reemerged in Southeast Asia. Movement of infected poultry and migratory birds and illegal bird trade was thought to be the causes of the spread.
How can humans contract the virus, then?
To contract the H5N1 bird flu, people have to come in close contact with the infected birds alive or dead.
Usually, the virus does not spread from person to person, according to the World Health Organization. The WHO says, there is no evidence that the disease can spread to people through properly prepared and cooked poultry food as the virus is sensitive to heat, and dies in cooking temperatures.
Then, should humans worry?
The virus - H5N1 is deadly and in the event of the virus mutating, it can become easily transmissible from person to person and potentially threaten to cause a pandemic.
Flu viruses are more prone to mutation as well because they have a segmented genome.
All known strains of flu – including the seasonal flu and the pandemic flu – have jumped from birds to humans in this way.
Bird flu in India
No case of bird flu in humans has emerged in India so far, according to the Union health ministry.
The department of animal husbandry has reported 25 episodes of H5N1 bird flu in poultry in 15 states from 2006 (when the first outbreak occurred in Maharashtra and Gujarat) till 2015. It has also been detected in crows.
How bad is the spread in India?
Many of the Indian states have reported a staggering number of infections. In Kerala, some 12,000 ducks had died and about 40,000 birds are said to be culled, according to Indian financial daily newspaper, Mint. In Madhya Pradesh, 400 crows were found dead in 10 districts. Over 1,900 migratory birds have died so far of avian flu in Himachal.
Around 100 birds were found dead in Rajasthan's Jhalawar district and since 5 December, hundreds of poultry birds have died at Haryana's Raipur Rani
Symptoms and treatments
The virus generally infects the gut in birds but while in humans, the virus can cause severe respiratory illness such as pneumonia or Acute Respiratory Distress Syndrome (ARDS).
Early symptoms can include fever, cough, sore throat, abdominal pain, and diarrhoea.
Hand hygiene is advised and those who work closely with the poultry industry are suggested to use PPEs. Antiviral drugs are said to ease symptoms.
In the US, the FDA approved a vaccine for the H5N1 virus in 2007.
Among poultry birds, vaccination strategies advised by the World Organisation for Animal Health can be used to prevent the flu, and the organisation recommends eradicating the highly pathogenic avian influenza (HPAI) at its source to decrease the disease in avian species and further human infections.