Tilapia in a tank. Photo Courtesy of Dr. Carla Phillips
In recent years, infectious diseases that directly impact us humans have been cropping up one after another. We have had Chikungunya, Ebola, Middle-East Respiratory Syndrome (MERS), Enterovirus D68 in the USA, a new version of H1N1 Influenza-A, Zika Virus and most recently an outbreak of Yellow Fever in southern Africa. However it is not just human illnesses we have to worry about when it comes to emerging diseases that could have a major impact on our well-being.
Enter a new virus that affects Tilapia, the fish that is central to fish farming around the world in an industry worth US$7.5 billion, providing a major food source as well as livelihood for people. Scientists have recently identified a previously unknown virus that has caused major die-offs of Tilapia on farms in widely separated countries – Israel in the Middle East and Ecuador and Colombia in South America. It has been called the Tilapia Lake Virus or TiLV.
TiLV seems to affect multiple systems in the fish, with some showing swelling of the brain and others showing liver disease. From the scientific studies done, it seems to bear a close relationship to the influenza viruses. Efforts are underway to develop diagnostic tests, control measures and a vaccine.
TiLV does pose a threat to the Caribbean region and Dr. Carla Phillips, aquatic and marine specialist at the UWI School of Veterinary Medicine in Trinidad, is very concerned. “We should therefore be aware and vigilant as a region and promptly report any clinical signs - (eye) abnormalities, skin lesions, ulcers/erosions, unusual spikes in mortality - to the Veterinary Services and, if available, the Aquaculture Extension service providers in our islands.”
TiLV is just one of the disease threats to animal health that, while it does not affect humans directly, can have a huge economic and food security impact – a major One Health issue. We know our veterinary services are paying close attention and the regulation of imports is strictly controlled.
This brings the question as to whether our own Turkey Vulture (Cathartes aura), affectionately called the “John Crow” locally, might be at risk from the NSAID drugs used here. Banamine® is available here and is used by veterinarians in horses, ruminants and dogs. Other veterinary NSAIDS available here include phenylbutazone used mainly in horses, carprofen (Car-o-pet®) for dogs and tolfenamic acid (Tolfedine®) for dogs and cats. Some human drugs such as meloxicam (Mobic®) and nimesulide (Nise®) may also be prescribed on occasion for dogs. Veterinary diclofenac is not registered or known to be available in Jamaica and the human formulation in not normally prescribed for dogs because of the much greater risk of harmful side effects such as stomach ulceration and kidney damage when compared to canine-specific preparations.
The answer to the John Crow question appears to be a reassuring ‘no’. In a study of Turkey Vultures and diclofenac toxicity, published in the Journal of Environmental Toxicology & Chemistry in 2008, it was determined that Turkey Vultures do not suffer the same toxic effects seen in the Old World Gyps sp. This study did not evaluate other NSAIDs, so some questions may remain. Also, the fact that NSAIDs are used in only a relatively small number of animals compared to the total population, and the practice of burying or incinerating carcasses suggest that the chance of exposure of our vultures to drug residues in carcasses they consume is very low.
1 - Barnett A., Rattner, Maria A., Whitehead, Grace,Gasper, Carol U., Meteyer, William A., Link, Mark A. , Taggart, Andrew A., Meharg, Oliver H., Pattee Deborah J., Pain, APPARENT TOLERANCE OF TURKEY VULTURES (CATHARTES AURA) TO THE NON-STEROIDAL ANTI-INFLAMMATORY DRUG DICLOFENAC, Environmental Toxicology and Chemistry, Vol. 27, No. 11, pp. 2341–2345, 2008
2 - J. Lindsay Oaks, Martin Gilbert, Munir Z. Virani, Richard T. Watson, Carol U. Meteyer, Bruce A. Rideout, H. L. Shivaprasad, Shakeel Ahmed, Muhammad Jamshed Iqbal Chaudhry, Muhammad Arshad, Shahid Mahmood, Ahmad Ali & Aleem Ahmed Khan Diclofenac residues as the cause of vulture population decline in Pakistan NATURE | VOL 427 | 12 FEBRUARY 2004
3 - Zorrilla, I., Martinez, R., Taggart, M. A. & Richards, N. Suspected flunixin poisoning of a wild Eurasian Griffon Vulture from Spain Conserv. Biol. http://dx.doi.org/10.1111/cobi.12417 (2014).
For an article from the Windsor Research Centre in Trelawny on our Turkey Vultures , click HERE.
The use of non-steroidal anti-inflammatory drugs (NSAIDs), specifically diclofenac, in food-producing animals in countries such as India and Pakistan has had a devastating spin-off effect which has affected ecosystem health in those countries. Drug residues the in carcasses of previously treated animals have resulted in the decimation of populations of various species of vultures of the genus Gyps.
Diclofenac, which is registered for human use in Jamaica under the trade names Voltaren® and Cataflam® among others, has been determined to cause acute renal failure and resultant visceral gout (deposition of uric acid crystals in the internal organs) in Gyps sp. In India and Pakistan, diclofenac is also marketed for veterinary use in livestock, and is apparently widely available and used. Animals that die are generally left to decompose in the open resulting in their consumption by the scavenging birds. Massive die-offs of vultures has resulted in some species being on the brink of extinction in the region.
There is some evidence that other NSAIDs such as flunixin meglumine (Banamine®) can also be toxic to Gyps sp. In 2014, a dead Eurasian Griffon Vulture (Gyps fulvus) was found to have died of visceral gout and was found to have significant levels of flunixin in its tissues – the first case of NSAID toxicity in a vulture outside of Asia.