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652 Australian Veterinary Journal Volume 82, No 11, November 2004

By the end ofOctober, 2004, 83tigers had died from

avian influenza or had beenculled as a quarantinemeasure to help contain thespread of the deadly H5N1virus at Thailand’s privateSri Racha Tiger Zoo.

The site of the world’slargest tiger breeding farm,Sri Racha’s tiger populationstood at 441 before theavian influenza outbreakthat is believed to havestarted when animals werefed raw infected chickencarcasses.

Fifty tigers were putdown by lethal injectionafter displaying avian flusymptoms while wildlife officials saidanother 33 tigers died of the H5N1 birdflu strain. Thailand’s bird flu preventioncentre said another five tigers were alsosick and are currently being treated withhuman-anti virus drugs.

The tigers, aged between eight monthsand two years, began dying on October14 after being fed chicken from the sameprocessing plant and the zoo was quicklyclosed to the public.

Five of Sri Racha’s zoo keepers wereplaced under surveillance after showingflu like symptoms but the other 800workers employed by the zoo and theoffending meat processing plant plusseveral hundred nearby residents,reportedly showed no signs of avian birdflu infection.

Officials said the culled tigers wereburied in pits behind the zoo and coveredwith lime and concrete to prevent theanimals from being dug up and theremaining tigers were being fed mincedpork instead of chicken.

A clouded leopard died in similarfashion at a Thai zoo earlier this year but

the World Health Organisation saidthe tiger deaths had no implications forhumans as tigers were not known to host

the human influenza virus.The Born Free Foundation has been

publicly critical of the conditions at theSri Racha Zoo which claims to be themost successful Bengal tiger breedingcentre in the world.

Members suggest the zoo has extensiveanimal welfare issues surrounding thetigers and has been investigated by Thaiauthorities for the illegal trade of tigerparts used for traditional Chinesemedicine.

Reports from the Animals AsiaFoundation and the EnvironmentalInvestigation Agency describe the zoo as atiger production line and in November2003 the zoo was raided with policefinding several hundred animals theowners could not properly account for. Ina study conducted by TRAFFIC in 2000,a Chinatown store owner in Bangkoktold investigators he purchased tiger penisfrom the Sri Racha Zoo.

A Thai government official is currentlyfacing disciplinary charges afterauthorising the export of 100 tigers fromthe zoo to a Chinese theme park in 2003.

Six Asian nations have reported aresurgence of the deadly H5N1 avianinfluenza virus. Thailand has confirmed11 human fatalities and Vietnam 19.

Over 100 million birdshave been culled acrosssouth-east Asia in anattempt to control the virusand scientific studies havesince demonstrated thatdomestic cats can beinfected with avian flu.

Responding to the crisis,CSIRO LivestockIndustries Australia hasdeveloped an experimentalvaccine to help protectchickens from the H5N1strain of avian influenza.

The trial vaccine usesImugene Limited’sadenoviral vectortechnology to delivergenetic material tostimulate the chickens’

immune responses. Testing of theexperimental vaccine has commenced atthe Australian Animal Health Laboratoryin Geelong, Victoria.

If successfully refined the vaccinecould provide a viable alternative toculling poultry in the advent of an H5N1outbreak. CSIRO’s Dr Chris Prideauxsaid the vaccine could be used to helpprotect the world’s poultry from furtheroutbreaks while maintaining surveillancefor disease outbreaks and ensuringhuman safety.

The vaccine works by delivering aportion of the avian influenza geneticmaterial, instead of the whole virus to thechickens making it possible to distinguishbetween vaccinated and infected birds.

According to Imugene, the vaccine issafer than live attenuated vaccines, is verycost effective for mass administration andcan be delivered to large numbers of birdsvia drinking water.

Avian influenza ravages Thai tigersBy Mark Thornley

Fifty tigers were put down and another 33 died of the H5N1 avian influenza virus