Bird Flu Alert: What is Avian Influenza? How critical is the new outbreak in India?

Avian influenza or bird flu has been reported in India mainly in four states -- Rajasthan, Madhya Pradesh, Himachal Pradesh and Kerala. Hundreds of migratory birds and crows are found dead. In Haryana, it is suspected that Avian deaths have occurred but the cause is yet to be confirmed. 

As per reports, in Himachal Pradesh’s Pong Dam Lake, nearly 2,400 birds were found dead. Kerala has even confirmed that the H5N8 strain of Avian influenza in parts of Alappuzha and Kottayam with deaths of 12,000 ducks and 36,000 more likely to be culled. Subsequently, a bird flu alert has been sounded in Rajasthan with hundreds of crows dying in several districts.

What is Avian influenza or bird flu?

Caused by Influenza Type A viruses that usually affects the poultry birds including chickens and turkeys, avian influenza or bird flu is a highly contagious disease. There are several strains of the virus and some of them are even mild leading to low egg production among other mild symptoms. However, others are fatal and severe.

The bird flue is mainly restricted to avians and the aquatic birds including ducks and geese are the natural reservoir of influenza A viruses. They are also the main players in the ecosystem of these pathogens and many birds carry the virus without witnessing any symptoms and eventually shed it through excretion. The virus can be transmitted to migratory birds who travel long distances from water birds. Once the virus jumps to terrestrial birds, it paves the way for infection to reach other mammals including pigs, horses, cats and dogs.

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How can bird flu infect humans?

While the bird flu outbreaks have been damaging poultry for several decades, it was first known in 1997 when humans began contracting the bird flu after an outbreak in Hong Kong’s live bird market. It was identified as the H5N1 strain of the influenza virus that caused the death of 6 out of 18 infected humans. Even though the H5N1 strain was contained, it against emerged a few years later in other parts of the globe causing hundreds of deaths among humans. 

Similarly, other strains of the virus including H5N2 and H5N8 jumped from animals to humans and thus triggering a global public health concern. Only the people who come in close contact with infected live or dead birds have contracted the H5N1 bird flu but it does not spread from person to person, according to the World Health Organisation (WHO). The UN health agency has also said that there is no evidence of the virus to spread from properly cooked poultry food because the virus is sensitive to heat. The mortality rate of bird flu among humans is also high.

Symptoms and treatment?

Major symptoms of H5N1 infection include 

• Cough
• Diarrhoea
• Respiratory difficulties
• Fever (over 100.4°F or 38°C)
• Headache
• Muscle aches
• Malaise
• Runny nose
• Sore throat

According to the US Centers for Disease Control and Prevention (CDC), bird flu is diagnosed by a test that is specifically designed to detect avian influenza called influenza A/H5 (Asian lineage) virus real-time RT-PCR primer and probe set. It offers results in four hours but reportedly the test is not widely available. The treatment varies depending on the kind of bird flu but in most cases, it is done with antiviral medication including oseltamivir (Tamiflu) or zanamivir (Relenza) to reduce the severity of the disease. The viruses, that cause the human form of the flu can easily develop resistance to two most commonly used antiviral drugs, amantadine and rimantadine (Flumadine). Hence, they should not be used.

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