Avian Influenza: Bird disease that can be deadly, but you won’t get it by eating chicken

As signs of the usual H5N1 panic start to set in, a look at the disease, its Indian outbreaks, and what makes it so deadly.

Written by Abantika Ghosh | New Delhi | Updated: October 24, 2016 1:57 pm
delhi, delhi zoo, delhi zoo timings, Deer park, delhi zoo shut, delhi swine flu, swine flu, swine flu deaths, delhi swine flu deaths, delhi news Migratory birds over the Yamuna in January 2015. (Oinam Anand/Express archive)

Just over a month after India declared itself free of Avian Influenza (H5N1), the Delhi Zoo and Deer Park in South Delhi have been shut following the deaths of several “local migratory” water birds. As signs of the usual H5N1 panic start to set in, a look at the disease, its Indian outbreaks, and what makes it so deadly.

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What is Avian Influenza?

Commonly known as bird flu, the disease usually spreads from bird to bird but may sometimes spread from birds to humans. Though human to human transmission — which takes place mostly after intimate and constant physical contact — is rare, the infection is virulent and, in an estimated 60% of cases, fatal. India is one of 6 nations in which the disease keeps surfacing among birds — during the last outbreak among poultry in Karnataka this May, 33,000 birds had to be culled. There is no vaccine against H5N1. According to WHO, some avian influenza viruses such as A(H5N1) and A(H7N9) “have caused serious infections in people”, with “the majority of human cases… (being) “associated with direct or indirect contact with infected live or dead poultry”. There is no evidence that the disease spreads to people through properly cooked food, even though “controlling the disease in animals is the first step in decreasing risks to humans”, says WHO.

What are the symptoms of the disease?

In humans, the symptoms of an H5N1 infection are the same as that of any other seasonal flu — fever, bodyache, sore throat, runny nose, headache, fatigue, etc.; however it can turn serious very quickly, and lead to respiratory distress. There was a phase of panic after scientists reported that a mutated bird flu virus could cause a human pandemic, and there were reports of such a mutation having been engineered in the laboratory through what is called an antigenic shift.

What has happened in Delhi?

The National Zoological Park was shut down Tuesday after the deaths of nine water birds from Avian Influenza. According to Zoo authorities, these were painted storks, ducks and pelicans that had migrated locally — a reason for concern because there is an increased possibility of the spread of the infection from wild birds to domestic poultry, which humans handle. Incidentally, migratory water ducks are the commonest carriers of bird flu.

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When did India become bird flu-free?

The Department of Animal Husbandry, Dairying and Fisheries in the Ministry of Agriculture and Farmers’ Welfare declared India free from Avian Influenza (H5N1) from September 5, 2016. India had notified an outbreak of Avian Influenza (H5N1) on May 9, 2016, at Humnabad in Karnataka’s Bidar district. “There has been no further outbreak reported in the country thereafter,” the government said in a statement on September 14. However, in a letter sent simultaneously to state chief secretaries, the Centre emphasised the need for continuous surveillance. Outbreaks have been reported earlier from Maharashtra, Telangana, Tripura and Manipur; according to information available with WHO, however, no human case or death has been reported in India since 2003.

Is it safe to eat chicken or eggs when an H5N1 strain is in circulation?

Perfectly so, if the food is well cooked. There are no known instances of the flu spreading through ingestion of the bird, even though people do contract it while plucking or culling an infected bird without proper protection, or if they are in a water body that has the droppings of an infected bird.

But is India prepared for a bird flu outbreak in humans, should it happen?

India has begun stocking up on Oseltamivir. Efforts are under way to ensure adequate availability of flu masks, and public health personnel have, in the past, been trained and laboratories prepared for an increased testing load, should it be required. The Department of Animal Husbandry has set up biosafety laboratories, and the Delhi government has said it has sufficient stocks of Tamiflu (Oseltamivir).