Scrambling to contain the spread of the highly pathogenic H5N1 bird flu virus, the Telangana government on 14 April ordered the immediate culling of 145,000 chickens on poultry farms located in a one-kilometre radius of the infected farm in Thorrur village of Hayathnagar mandal in Ranga Reddy district.

This is the first ever outbreak of the disease reported in the states of Telangana and Andhra Pradesh, according to Times of India on 15 April.

Simultaneously, a ban on trading of all poultry products from farms in a 10-kilometre radius 'surveillance zone' was put in place.

The outbreak of the disease had an immediate impact with the Telangana Poultry Breeders Association staring at a loss of over 300 million rupees (INR), especially after Andhra Pradesh banned entry of all poultry products into its territory.

Authorities in Hyderabad said the outbreak came to light after several birds started mysteriously dying in Srinivasa Reddy Poultry Farm owned by V. Balakrishna Reddy in Thorrur village from 8 April, prompting them to send bird samples to a testing laboratory in Bhopal.

"The tests confirmed that it was the H5N1 virus and we advised the animal husbandry department in Telangana and the Centre to take all appropriate measures," D.D. Kulkarni, joint director, High-Security Animal Disease Laboratory, told Times of India from Bhopal.

Within hours, dozens of animal husbandry workers wearing protective gear, began the culling operation in the infected farm and put the birds and eggs in huge gunny sacks and buried them in deep pits.

Dr D. Venkateswarulu, director of animal husbandry department, told reporters in the afternoon that the culling operation in farms located in one-kilometre radius would be completed in the next 48 hours. This will be followed by sanitisation and disinfection operations.

A Central Rapid Response team comprising Dr S.K. Jain and Dr Pranay verma, both avian influenza specialists, is arriving in Hyderabad to oversee the culling.

Meanwhile, the department staff have begun collecting serum and dropping samples of the birds from farms in the 10-km radius to be tested for the virus. If any of the tests come positive, then the government will widen the culling operations. Containment in the surveillance zone will be in place for a week or 10 days until all tests are completed.

Dr Venkateswarulu said they were collecting information on egg sales over the past 20 days from Balakrishna Reddy's farm, to find out where they were transported. If it is found that the stock is yet to be sold, they will order destruction of such eggs. If the eggs were sold to other states, then the department will immediately notify the states and provide them information so that the eggs can be destroyed.

The official said that chicken or eggs procured from farms outside of the surveillance zone can be consumed and there was no cause for panic. If the chicken is well cooked or the egg boiled, then there is no danger of contracting the virus by humans. If these are cooked at 70°C and above for 20 minutes, the virus will die, Dr Venkateswarulu said.

While weather does play a role in the spread of flu, Dr Venkateswarulu said that the most accepted theory is that the disease is spread by migratory birds which is contracted either by the chicken directly or through an intermediary carrier bird species.

In 2006, the government in Andhra Pradesh carried out some preventive culling but the enormity of the task this time around has everyone anxious. In Hayathnagar, authorities supplied 2,500 tamiflu tablets to health workers. Health department officials also began a massive house-to-house surveillance with 300 Asha, ANMs and multi-purpose health workers, said Dr G Srinivas Rao, joint director, Epidemic Cell, Telangana.

"We are not leaving anything to chance and will take up all efforts to stop the virus from spreading. The swine flu isolation wards will be used in case there is any need," he told Times of India.

Since 2003, there have been 400 human deaths globally from the H5N1 strain and hundreds of confirmed cases of infection. In India, the virus was first detected in Jalgaon, Maharashtra, in 2006 and ever since reports of fresh outbreaks have been sporadically reported from all corners of the country. The last outbreak occurred in Kerala in January 2015.