On a farm in the Rangareddy district in India, near the southern metropolis of Hyderabad, a clutch of chicks has just been delivered. Some 5,000 birds peck at one another, loitering around a warehouse which will become cramped as they grow. Outside the shed, stacks of bags contain the feed they will eat during their five-week-long lives. Some of them gulp down a yellow liquid from plastic containers – a sugar water fed to the chicks from the moment they arrive, the farm caretaker explains. “Now the supervisor will come,” she adds, “and we will have to start with whatever medicines he would ask us to give the chicks.”

The medicines are antibiotics, given to the birds to protect them against diseases or to make them gain weight faster so more can be grown each year at greater profit. One drug typically given this way is colistin. Doctors call it the “last hope” antibiotic because it is used to treat patients who are critically ill with infections which have become resistant to nearly all other drugs. The World Health Organisation has called for the use of such antibiotics, which it calls “critically important to human medicines”, to be restricted in animals and banned as growth promoters. Their continued use in farming increases the chance bacteria will develop resistance to them, leaving them useless when treating patients.

Yet thousands of tonnes of veterinary colistin was shipped to countries including Vietnam, India, South Korea and Russia in 2016, the Bureau can reveal. In India at least five animal pharmaceutical companies are openly advertising products containing colistin as growth promoters.

One of these companies, Venky’s, is also a major poultry producer. Apart from selling animal medicines and creating its own chicken meals, it also supplies meat directly and indirectly to fast food chains in India such as KFC, McDonald’s, Pizza Hut and Dominos.