Of Vultures and Pain Killers

A colleague who is visiting our Poison Control Center from Europe recently asked me if I knew anything about vultures and non-steroidal anti-inflammatory drugs, specifically diclofenac (which goes by the ironically alliterative trade name Voltaren®). I had never heard of any connection. It turns out that the near extinction of the dominant species of vulture in the Indian subcontinent is linked to this pharmaceutical.

The great vulture die-off in India, Pakistan, and Nepal began in the 1990s and remained a mystery at first. Finally, it was discovered that the culprit was diclofenac. This drug had been administered widely to livestock, apparently to increase performance by limiting the everyday aches and pains that afflict a beast of burden. It turned out that even very low levels of this drug, well tolerated by cows or even people, are lethal to certain bird species. Most prominently this was so for the type of vultures that live, or rather lived, in India and surrounding countries. When these vultures feasted on dead livestock, as they were wont to do, their kidneys simply shut down from the residual diclofenac in the carcasses that they fed upon. The link was so well-established that in 2006 the Indian government actually banned any further veterinary use of diclofenac (followed by bans in neighboring countries). Despite this, by 2010 it was estimated that the populations of long-billed and slender-billed vultures, birds that had once filled the skies in an Indian equivalent of a carrion-feeding passenger pigeon, had fallen by 97% and almost 100% percent, respectively: from millions, 45,000 and 1,000 remained (http://news.nationalgeographic.com/news/2008/05/080501-vultures-extinct…).

Indian vultures are not unique in their susceptibility to diclofenac: sophisticated scientific testing has also shown that Eurasian and African vulture species are also at least at as much risk (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1618889/). Just last month, the journal Nature reported the news (initially published in a small circulation scientific journal) that the first confirmed death of a European vulture had occurred due to a non-steroidal anti-inflammatory. Only it wasn’t diclofenac, but rather a related pharmaceutical, flunixin (veterinary-approved use only in the U.S.) (http://www.nature.com/news/poisoned-vulture-could-herald-european-bird-…). Despite this, the European Union has not yet banned veterinary use of any non-steroidal pharmaceutical, although there is active campaigning for such restrictions by NGOs, including the Vulture Conservation Foundation (http://www.4vultures.org/about-us/). The New World vultures, which would include the endangered California Condor, appear to be resistant to non-steroidal anti-inflammatory toxicity – so the Condor only has to fend off lead poisoning from carcasses laden with bullet fragments (https://www.pwrc.usgs.gov/MissionAreas/EnvironHealth/Contaminantdiclofe…).

Vulture conservation may seem a pretty esoteric concern, but the species collapse on the Indian subcontinent has carried some painful lessons for human ecology. For example, the absence of vultures has led to a significant increase in the population of feral dogs feeding on abandoned carcasses. Such dogs are main reservoir for the scourge of rabies in India, already a major killer there. There has even been a negative cultural-spiritual impact, most notably in terms of Zoroastrian funerary practices (http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2011.06293.x/pdf).

For those that argue that through personal-level action we can change the impact of agribusiness pharmaceutical use, what has happened to the vultures of vegetarian-dominant Indian serves as a cautionary tale. Simply buying antibiotic-free chicken is not going to do the trick. The importance of finding solutions on a national scale, at least, has been underscored by the work of the National Resources Defense Council (http://www.nrdc.org/food/saving-antibiotics.asp). Moreover, as the diclofenac case shows, problems with veterinary pharmaceuticals transcend antibiotics alone. Veterinary and human pharmaceuticals are interconnected. The business world recognizes this. For example, at Novartis (which owns Voltaren®) the over-the-counter (OTC) and animal health businesses are combined as a “Consumer Health” unit, which has seen profits rise in part due to OTC sales of diclofenac (http://www.novartis.com/newsroom/media-releases/en/2014/1866170.shtml).

Besides rabies, other human diseases have also been argued to be at risk of increasing due to the vulture kill-off, for example, anthrax in Bangladesh. Since anthrax is a potential bioterrorism weapon, maybe to get action this can be coached as a homeland security issue. It certainly is a matter of home-planet security.