Steve Quayle News Alerts

June 20, 2003
From: Lindsay Oaks <loaks@vetmed.wsu.edu>

Re: Vulture die-off - India: RFI 20030612.1447
----------------------------------------------
The article from the The Hindu of Bangalore refers to the work of
veterinarians and biologists working on The Peregrine Fund's investigation
into the decline of Asian Gyps vultures, the results of which were recently
presented at the 6th World Conference on Birds of Prey and Owls, Budapest,
Hungary, 18 to 23 May 2003. These studies have focused on the rapid and
dramatic decline of the oriental white-backed vulture (_Gyps bengalensis_)
in Pakistan, which is due to acute renal failure (in birds, renal failure
is manifested as visceral gout) and death in the breeding vulture population.

Residue studies and experimental challenges have implicated the
non-steroidal anti-inflammatory drug (NSAID) diclofenac as the cause of
renal failure. Contrary to the suggestion in The Hindu, we have not
performed LD50 studies and cannot make the statement "even at low doses, it
is toxic to vultures." Although this initially seemed rather surprising to
us as well, surveys have shown that in Pakistan veterinary diclofenac is
widely available over the counter, inexpensive, a relatively recent
introduction to the veterinary market, and quite popular.

We are still investigating the route of exposure to the vultures. As Conor
Kretsch points out [Vulture die-off - India: etiology 20030613.1459], the
human use of diclofenac in Europe and the USA is substantial enough to lead
to aquatic and terrestrial contamination. Diclofenac is also commonly used
in people in Pakistan and India, and so presumably there will be
environmental contamination there as well.

However, based on the observations that (1) NSAIDs are unlikely to
bioaccumulate, (2) NSAID-associated renal failure is generally dose
dependent, (3) veterinary diclofenac use is ubiquitous, and (4) dead
animals are typically left out for the vultures to eat -- we suspect that
contaminated carcasses are the most likely source of exposure. Also under
investigation are the reasons for the apparent selective effects on
vultures versus other avian and mammalian scavengers. As also alluded to by
Conor, these may be due to behavioral differences that lead to differences
in exposure, physiologic differences in sensitivity to diclofenac, or both.

Although we believe that diclofenac is the primary problem in Pakistan, and
there are many parallels between the declines in both countries, the
problem in India appears to [be] more complex with other species of Gyps
vultures, different and more varied food sources, and some apparent
differences in the epidemiology of vulture mortalities. The possible role
of diclofenac in the vulture declines in India, as well as other potential
causes, are being evaluated by the UK Royal Society for the Protection of
Birds and their colleagues in India. As far as we know, there is no direct
evidence that funerary practices by the Parsees at the Towers of Silence in
Bombay have resulted in diclofenac exposure to the vultures there, or were
responsible for the declines in that area.

--
J Lindsay Oaks
Department of Veterinary Microbiology and Pathology
Washington State University
email <loaks@vetmed.wsu.edu>

[We are grateful to Dr Oaks for these clarifications. While some of the
arguments, pointing at diclofenac as an etiological factor in the vulture
decline in Pakistan, are circumstantial -- the Washington State University
researchers have backed their suspicions by residue studies (in vultures
from Pakistan?) and experimental challenges (which were not LD50 studies).
It would be helpful to obtain more details about these studies and
experiments. Recent research in India has been reviewed in the article
"Glimmer of hope for India's dying vultures" (New Scientist, 16 Apr 2003
<http://www.newscientist.com/news/news.jsp?id=ns99993739>). See also the
website <http://www.vulturedeclines.org/home.asp>. - Mod.AS]

[see also:
Vulture die-off - India: etiology 20030613.1459
Vulture die-off - India: RFI 20030612.1447
Vulture die-off - India, Pakistan, Nepal 20030212.0375]

http://www.promedmail.org