Everything in our world is interconnected in very complex and sometimes fragile ways.
In the arthritis clinic, one drug that comes up is diclofenac (2-(2,6-dichloranilino) phenyl acetic acid). It’s a non-steroidal anti-inflammatory. It works to inhibit the COX enzyme, but also seems to have some anti-bacterial properties as well. It’s a great medication, and it helps a lot of people. However, while reading about diclofenac, I found out that it was prohibited for veterinary use in India, Pakistan, and Nepal. Intrigued by this, I investigated further and found out the fascinating story.
In the 1980’s, there were around 80 million Gyps bengalensis vultures in South Asia. They were considered the most abundant raptor in the world and they formed an essential part of the ecology of the region. As scavengers, they cleaned up the remains of dead animals all over the Indian subcontinent. Unfortunately, over the intervening decades they have become an extremely endangered species, with only the small populations of a few hundred individuals in Cambodia and Burma as viable sources to renew the species. Like many species they have difficulty breeding in captivity, the first chicks born in captivity in 2007, died.
Why are these birds in such decline and what does this have to do with arthritis? These birds are extremely tough, their ecological niche is feeding off of dead, often diseased and rotting corpses. They are mostly resistant or immune to the infections that kill livestock including anthrax and brucellosis. In that way they help stop the spread of major cattle infections, by cleaning up the remains. However, they are incredibly sensitive to diclofenac. Even a small amount of diclofenac causes them to develop gout-like crystal deposits throughout their organs. So, where are they getting all this diclofenac? Well, it’s there for the most kindly of reasons. In India, old cows are treated very well. Unlike places like the US, where an aging cow would quickly be sent to make hamburgers, leather and glue, in India old cows, many of which have served their owners with years of hard work, providing milk or pulling a plow, are well cared for. As they develop joint pain and arthritis they are given medication to help them, including diclofenac. Unfortunately, when these cows die, the vultures come in, take a bite then rapidly become sick and die.
Cows are not the only thing on the vulture menu. All the other carcasses and other material the vultures used to eat is laying, rotting and waiting for another species to step up. This has led to an upsurge in wild dogs. Huge populations of wild dogs now roam South Asia because of the abundance of food available; India has tens of millions of them. Wild dogs in a populous country interact with humans, often in negative ways, with 80,000 reported bitings reported in Mumbai in 2011.
Unfortunately, there is another species, a viral species, which is also prospering in India. The rabies virus thrives in these wild dogs which means transmission through bites to humans. Resulting in the deaths of about 20,000 people from rabies each year in India, mostly young children; with another approximately 5,000 deaths a year in Pakistan.
It’s also not only the dogs that are increasing because of the abundance of food, but also the rats, known disease vectors for all manner of parasites and infections, including the bubonic plague.
Obviously, efforts are underway to ameliorate this situation, as diclofenac sales for veterinary uses are now prohibited. There are large scale efforts to curb the wild dog populations, including catch-sterilize-release efforts, along with vulture conservation programs.
There are other far reaching impacts of this decline in vultures, in the Parsi population (Queen singer Freddie Mercury was a Parsi) of India. Traditional funeral practices involve putting the deceased on an elevated, open-air platform (Towers of Silence), where the vultures would remove the remains within hours. Now, this isn’t happening, and the Parsi community, one of the wealthiest groups in India, is working hard to come up with effective solutions. Having human corpses just sitting for long periods, particularly the monsoon season is not great for anyone.
Thousands of children are dying each year because these vultures don’t have the enzyme to help them digest diclofenac, given by kindly people to take care of cows with arthritis. I think one of the major lessons here is the vast interconnected of the world and the great impact of unintended consequences. One small molecule can have a huge impact.
