India has once again been hit by an outbreak of the H591 bird flu, with only Maharashtra and Bihar so far having reported cases of deaths in birds from the highly contagious virus at poultry farms.
The latest outbreak appears to have first hit Bihar on February 16 at a poultry research farm in Patna, where the virus killed 787 out of 3,859 birds and all of the remaining birds were culled, World Organisation for Animal Health (OIE) said, citing a report from government officials. It has since spread to Maharashtra, with farms in Thane and the neighbouring Palghar districts reporting outbreaks.
"Around 100 birds died at the poultry farm in Vehloli village in Shahapur tehsil recently. Their samples were sent to a Pune-based laboratory for testing and the results confirmed that they died due to H5N1 avian influenza," Chief Executive Officer (CEO) of the Thane Zilla Parishad, Dr Bhausaheb Dangde, said.
On February 19, Palghar's district veterinary officer Dr Prashant Kamble said that some birds at the poultry farm in Vasai-Virar region died, after which their samples were sent for testing.
But what exactly is bird flu and how does it spread? And should you worry about consuming chicken and eggs? Here's a lowdown
What is bird flu? When was the first outbreak reported?
Bird flu or avian influenza is a highly contagious viral disease that affects both domesticated and wild birds. It refers to infections caused by the Type A virus in the intestines and respiratory tracts of wild aquatic birds, which usually do not get sick. Avian influenza A viruses are, however, very contagious among birds and some of them can even kill domesticated bird species such as chickens, ducks and turkeys.
The first outbreak of the virus was reported in China in 1996. In India, the first cases were reported in Nandurbar, Maharashtra, in 2006.
How does the disease spread?
The primary source of the infection is through bird faeces. The virus can spread through direct contact with bird excreta from infected birds, especially through faeces or contaminated feed and water. The bird flu viruses are resistant in nature, can survive for long periods when temperatures are low and spread easily from farm to farm. They can also be carried on farm equipment.
Wild birds can normally carry bird flu viruses in their respiratory or intestinal tracts but they do not commonly get sick. This allows them to carry the viruses on long distances along their migration flyways.
Is bird flu caused by a single virus or are there different strains?
There are many bird flu virus strains, which are usually classified into two categories according to the severity of the disease in poultry: low pathogenic (LPAI) strains, which typically cause few or no clinical signs in poultry, and highly pathogenic (HPAI) strains, which can cause severe clinical signs and potentially high mortality rates in poultry. Differentiation between low and high pathogenicity is based on the results of laboratory tests.
Does the disease spread from birds to humans?
People in close contact with infected birds risk acquiring avian influenza. While many human cases are limited to conjunctivitis or mild respiratory disease, some viruses tend to cause severe illnesses.
The virus has claimed 407 human lives globally between 2003 and 2014, according to the World Health Organisation.
The disease’s first outbreak in India was recorded in 2006 in Gujarat and Maharashtra. Cases were found in West Bengal and Kerala in later years. India had outbreaks of the flu among birds in 15 states between 2006 and 2015, and no humans have been infected in the country so far.
India declared itself free of the virus in September 2019.
Can eating chicken and eggs cause bird flu?
There is no evidence to suggest that the consumption of poultry or eggs could transmit the bird flu virus to humans but scientists recommend cooking the poultry at temperatures upwards of 70 degrees Celsius for safety.
For eggs, it is advisable to purchase only fresh produce and those bought from trusted sources. A runny yolk is an indication that the egg is stale or may be infected, and must be avoided.
What are the measures to prevent an outbreak?
If the infection is detected in animals, a policy of culling the infected and contact animals is normally used in an effort to rapidly contain, control and eradicate the disease. When outbreaks are detected, culling is generally carried out at the infected farm or within a short radius of the infected premises in conjunction with active surveillance.
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