The deaths of at least 17 birds in the national capital and 15 painted storks in Gwalior zoo in suspected cases of avian influenza has led to concerns among citizens over the spread and tranmission of the disease, but experts said that there is no reason for panic yet.
On October 18, the National Zoological Park in Delhi shut down temporarily after several birds died of bird flu. In the following days, reports said five ducks in Hauz Khas' Deer Park and three crows in Sunder Nagar in the national capital had died of suspected bird flu. On October 21, the Gwalior zoo in Madhya Pradesh closed down after the painted storks died.
In a press release the same day, the Animal Husbandry Department under the Ministry of Agriculture said that samples of birds received from the Delhi and Gwalior zoos had tested positive for the H5N8 strain of the avian influenza virus. This is the first time this strain has been reported in India.
Experts, however, said that the H5N8 sub-type, which has been detected in some Asian and European countries previously, has not been known to infect humans so far.
In India, which first had a bird flu outbreak (of the H5N1 strain) a decade ago, no cases of the virus infecting humans have been reported yet.
“Particular kinds of people such as handlers of birds, vets, people in the poultry business, cullers, those who handle carcasses of birds, may be at risk,” said Dr Abhay Choudhary, head of microbiology department, JJ Hospital, Mumbai. “But there is species barrier to transmission of the disease to humans. So, it is rarely known to spread.”
Experts also clarified that eating cooked meat is safe.
28 bird flu outbreaks so far
Since the disease was first reported in Maharashtra's Nandurbar district in 2006, there have been 28 outbreaks in India, of which just a handful have made national news. The last outbreak was in Manipur in April 2015, when 21,000 birds had to be culled to contain the spread of the virus.
The outbreak of the H5N8 strain of bird flu in India comes a month after the Department of Animal Husbandry said that India has "declared itself free from avian influenza [H5N1] from September 5 and notified the same to the World Organisation for Animal Health.
The World Organisation for Animal Health, an intergovernmental organisation that works on improve the health of animals worldwide, had earlier said that H5N8 flu is not known to cross human barriers.
Chaudhary reiterated this. “It is not a regular infection that invariably spreads to humans, like say the H1N1 virus [earlier known as swine flu],” he said.
The Animal Husbandry Department has requested the Ministry of Environment, Forests and Climate Change to issue advisories to all wildlife and bird sanctuaries in the country.
Chaudhary said that consuming poultry cannot transmit the infection. “Bird flu can spread through droplet transmission," he said. "If we are able to restrict the spread of the flu in birds, the possibility of it spreading to humans is automatically reduced."
He added: "Every virus is known to have different host specificity. There is always a risk that the virus will jump the species barrier and infect humans. Hence, we do culling of the host population.”
In 2009, the government passed the Prevention and Control of Infectious and Contagious Diseases in Animals Act, which directs the isolation of infected animals in case of a disease outbreak and allows them to be culled, if deemed necessary.
So far, the government has paid Rs 2,622 lakhs as compensation to poultry farmers in India whose birds were culled to curtail the spread of bird flu.
The bird flu virus is carried in the respiratory or intestinal tracts of wild and migratory birds. It spreads to domestic birds through direct contact with secretions from infected birds, especially their droppings, or through contaminated food and water.
Most avian influenza viruses do not infect humans. However, sub-types, such as H5N1 and H7N9 have been known to cause serious infections in humans. The virus is transmitted to humans only when there is close contact with infected birds or heavily contaminated environments.
Since 1997, 660 cases of human avian influenza H5N1 have been reported in the world, of which 385 were fatal. Infections and deaths have been reported from India’s neighbouring countries such as Pakistan and Bangladesh.
“This disease does not spread to humans directly,” said AS Ranade, dean of Krantisinh Nana Patil College of Veterinary Science, Shirwal, Maharashtra. "The virus needs to undergo mutation or genetic change to infect humans. It needs a mixing vessel in the form of another species, a pig for instance. We do not have a mixed farming culture here in India. Our commercial farms are very clean and well maintained. That reduces the chances of spread of the disease to humans."
Her added that the Indian methods of cooking, which includes boiling the chicken and use of spices, further reduces chances of infection, unlike other countries where half-cooked meat is consumed.
“The virus is very fragile, and cannot survive easily," said Ranade. "There is no need to panic."
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