Two internationally renowned South African vets are in a race against time to solve a bacterial infection that is killing thousands of critically endangered antelope in central Asia. In the past three weeks 130,000 saiga antelope have dropped dead on the plains of Kazakhstan.There were already only 300,000 of these nomadic antelopes alive.It is the largest mass "die-out" of saiga, which have survived previous but smaller mass deaths.Johan Marais, a veterinary surgeon, and Johan Steyl, a wildlife pathologist specialising in disease conditions in antelopes, left for Kazakhstan on Friday and are now working fervently to determine what triggered the outbreak of the bacteria, Pasteurella.Marais and Steyl - who are based at the University of Pretoria's Onderstepoort faculty of veterinary science - are part of Saving the Survivors, an organisation that treats endangered animals.The two were seconded to the international investigation after South African aerospace and defence company Paramount Group learnt, in recent dealings with the Kazakhstan government, that entire herds were being wiped out.Marais said he had never encountered such a massive "die-off" in a species in such a short space of time."We know the deaths were caused by Pasteurella, but we need to figure out what the trigger is and how to treat the remaining population so this does not keep occurring.They were hoping to gain physiological clues from post mortems."Once blood, DNA and post-mortem results are analysed we should be a step closer to solving this mystery," he said.Suzanne Boswell Rudham, a Saving the Survivors spokesman, said no trigger for the bacteria had been discovered to date.The vets had conducted site visits to determine if there was a possible environmental cause for the deaths, such as contamination from pollution."Saiga, which are unique to the area, are extremely resilient, living in deserts and semi-arid areas."They are not first getting sick and then dying. They are literally falling over dead. The cause [of death] is a complete mystery."She said Marais and Steyl had been asked to investigate because of their work and knowledge."It is hoped they will bring a fresh perspective to the investigations. The test results should be known within a week."..