India | The human cost of the disappearance of vultures

The near-complete disappearance of vultures in India is causing 100,000 human deaths each year, according to a study.

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Forty years ago, there were 40 million vultures in India. Now, there are barely 20,000. The culprit: diclofenac, an anti-inflammatory ingredient found in, for example, Voltaren ointment in Canada. In India, it is used by veterinarians.

“The disappearance of vultures in India is a catastrophe that has hit people’s minds a lot,” says Anant Sudarshan, an economist at the University of Warwick in England who co-authored a study published in July in theAmerican Economic Review.

Vultures were eating dead animals, which in India are often left lying around, Sudarshan said. This increased the circulation of infectious diseases, including rabies, which was spread by stray dogs that were more numerous because of the greater availability of carcasses to eat.

Mr Sudarshan and his colleague Eyal Frank calculated that between 2000 and 2005, the disappearance of vultures increased the number of deaths by 100,000 each year in India. That equates to a societal cost of US$70 billion per year. The calculation takes into account India’s lower GDP per capita than the West.

Patent

The root of the problem was the end of the patent on diclofenac in 1994. The price of the painkiller plummeted and Indian veterinarians began prescribing it to many farmers for mastitis and hoof problems in cattle. When animals died in the fields, vultures were poisoned with diclofenac.

The mystery of the disappearance of Indian vultures was solved by American biologists in 2004, leading to a ban on veterinary diclofenac in India in 2006. But farmers got around the problem by using human diclofenac. In 2020, human diclofenac was also severely restricted.

“Now there is the same problem in Africa,” Mr Sudarshan notes.

Not in Canada

“It’s often talked about at conferences,” says Guy Fitzgerald of the University of Montreal’s School of Veterinary Medicine. “Here in Canada, diclofenac is not approved for veterinary use, except as eye drops.”

The painkiller recommended in India as an alternative to diclofenac, meloxicam, is preferred in Canada, according to Merle Olson, an Alberta government veterinarian who has written leaflets on meloxicam. “Meloxicam doesn’t cost much more,” says Dr.^r Olson: “A lot of times, availability in a market depends on a company creating a production line and then pushing for approval.”

Diclofenac does not have a very harmful effect on North American birds, according to the D^rs Fitzgerald and Olson.

Another difference between Canada and India: Here, animals that die are not abandoned in the fields, notes Stéphane Lair, also of the School of Veterinary Medicine at the University of Montreal. Sudarshan adds that water treatment systems are more common in the West than in India.

In Europe, isolated cases of vultures being poisoned by diclofenac have been reported, prompting calls for a ban there too.

Babies and bats

The study’s other co-author, Eyal Frank of the University of Chicago, published the paper in early September in the journal Science a study illustrating the same phenomenon, but with bats in the United States. A fungus is decimating bat colonies in North America, including Quebec. This “white-nose disease” is causing insecticide sales to soar, because bats eat insects and so their absence increases the number of biting insects. Mr. Frank’s analysis shows that in American counties affected by white-nose disease, insecticide sales increase by 31%. This has a detrimental effect on infant health, according to his analysis: infant mortality increases, by an average of 7.9%.

Other examples

Beyond the disappearance of vultures and its effect on human health, this story shows the importance of looking at biodiversity loss from multiple angles, Frank said.

Are there other examples like this? Frank notes a study showing that in Wisconsin, the reintroduction of wolves reduced car-deer collisions. A 2020 study calculated that the societal benefits of this reduction in car accidents were 63 times greater than the losses to ranchers whose livestock were attacked by wolves.

Vulture researchers also cite a study showing that tree losses linked to the emerald ash borer increased cardiovascular and respiratory diseases in the most affected cities, due to the loss of the filtering effect of ash trees.

Funeral

The disappearance of vultures even has a religious and cultural impact among the Parsis in India. An article in the journal VQR reported a controversy in the community over their 2,000-year-old funeral rite. The Parsis leave their dead on “towers of silence” where they were traditionally eaten by vultures. The remains now rot, leading to a debate over whether the community should adopt cremation.