Update 9 June 2015: More than half the world's enigmatic saiga antelopes – some 134,000 animals – have been wiped out in Kazakhstan within just three weeks. The culprit has been identified as haemorrhagic septicaemia, caused by the bacterium Pasteurella multocida, according to the World Organization for Animal Health, which says the outbreak is now over. 
 
 Original article, published 27 May 2015 
 
 The death toll of iconic saiga antelopes in central Asia has soared to around 120,000, almost half of the world's remaining population, according to unofficial estimates. Today vets and scientists investigating the catastrophe presented their results so far to government officials in Kazakhstan, where the animals are dying. 
 
 "The current official figure is 85,000, but we are hearing unofficial estimates in excess of 100,000, approaching 120,000," says Aline Kühl-Stenzel of the UN Convention on Migratory Species. 
 
 The animals began dying from an unidentified cause around 10 May. The death toll soared within days to 27,000, at which point the Kazakh government requested help from the secretariat of the convention. A team of vets, led by Richard Kock of the Royal Veterinary College in Hatfield, UK, flew out on Friday. 
 
 "It's very dramatic and traumatic, with 100 per cent mortality," Kock told New Scientist from Betpak-Dala in central Kazakhstan. "I know of no example in history with this level of mortality, killing all the animals and all the calves." The animals die through severe diarrhoea and difficulty breathing. 
 
 Trio of possibilities 
 
 From tissue samples collected earlier by Kazakh researchers, Kock and colleagues have narrowed the cause to three possibilities. One is haemolytic septicaemia, caused by bacteria that are normally harmless, and which also kills buffalo. 
 
 Another, less likely culprit is epizootic haemorrhagic disease, a viral disease transmitted by mosquitoes. "We have to do more tests to rule that out," says Kock. The other possibility is toxaemia caused by clostridia bacteria. "We need all the lab tests to be completed and a comprehensive analysis before we can reach any firm conclusions." 
 
 The reason so many animals died at once is linked to the fact that the local females all calve within one week, providing ideal conditions for disease to spread between the animals and to their calves. 
 
 In 2014, there were an estimated 200,000 animals in Betpak-Dala, with a further 60,000 in other regions of central Asia, down from more than a million saiga in the 1990s. 
 
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 A mass die-off of wild antelopes in Kazakhstan was triggered by environmental factors, scientists believe. 
 
 More than 200,000 saiga antelopes collapsed and died suddenly in 2015, wiping out most of the global population. 
 
 The deaths were found to be caused by a bacterial infection. 
 
 However, new data shows other factors were involved too, including unusually high humidity and temperatures. 
 
 Researchers think changing environmental conditions could be a trigger for the bacterial onslaught, although this needs further research. 
 
 They say there is a high chance of the same thing happening again, given climate change predictions for the region. 
 
 Study leader Prof Richard Kock of the Royal Veterinary College London was part of the original emergency response team. 
 
 He said the event went way beyond what would normally be expected from a bacterial disease of this kind. 
 
 "The whole thing was really extraordinary," he said. "It's very very likely to happen again." 
 
 The multi-disciplinary team used statistical analysis to look at environmental conditions at the time. 
 
 Image copyright Joint saiga health monitoring team, Kazakhstan Image caption Newborn saiga calf: Numbers have risen again since 2015 
 
 They found that there were unusually warm temperatures and high humidity in the days leading up to the wildlife deaths. 
 
 The same was found for two previous mass die-offs of antelopes in 1981 and 1988 in central Asia. 
 
 The mechanisms by which climate factors triggered this bacterial attack remain unknown, and require future research, they say. 
 
 A link with climate had been noted before, but, "this is the first concrete evidence", said Prof Kock. 
 
 There is an urgent need for mitigation of other risks to the critically-endangered animal, such as poaching and the spread of diseases from livestock, he added. 
 
 "There's theoretically a possibility of extinction of the species entirely," he said. "We have at least got a number of populations - albeit small ones - that are outside the danger zone." 
 
 Other wildlife, such as reindeer, could also be susceptible to mass die-offs, scientists believe. 
 
 Image copyright Joint saiga health monitoring team Image caption Skull from a saiga with the horns sawn off: High levels of poaching have depleted numbers 
 
 The antelopes all died within days of each other over a large area of central Kazakhstan. 
 
 It later emerged that the most likely cause was blood poisoning from a bacterium found naturally in saiga antelopes, which is usually harmless. 
 
 Co-researcher Steffen Zuther of the Frankfurt Zoological Society/Association for the Conservation of Biodiversity of Kazakhstan said mass mortality events are a major threat for the saiga antelope and can wipe out many years of conservation work in a few days. 
 
 "The triggering of such mass mortality events in saiga through weather conditions shows that not much can be done to prevent them occurring, and therefore how important it is to maintain saiga populations of sufficient size for the species to survive such catastrophes," he explained. 
 
 "The event was simply catastrophic for the long-term survival of this critically endangered species," said Nida Al Fulaij of the wildlife charity, PTES, which funded some of the rescue work. 
 
 The saiga antelope lives on the grasslands of Central Asia in large herds of up to a thousand individuals. 
 
 The International Union for the Conservation of Nature says the animal is at risk from illegal hunting for horns used in Chinese traditional medicine, as well as from habitat loss and grassland fires. 
 
 The research is published in the journal, Science Advances. 
 
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– After many thousands of years roaming much of central Asia, the saiga antelope has had a terrible couple of decades—and a devastating few weeks. A mysterious illness that causes severe diarrhea and breathing difficulties has wiped out what could be up to half of the remaining population of the species, New Scientist reports. Officials in Kazakhstan say the disease has killed 85,000 of an estimated world population of 257,000 since about May 10, but experts say they've heard unofficial estimates closer to 120,000. The species—known for its distinctive tubular nose, the AP reports—numbered more than a million in the 1990s but has been in decline since, thanks in large part to poachers, and was already considered critically endangered before the latest die-off. "It's very dramatic and traumatic, with 100% mortality," the leader of an international team investigating the outbreak tells New Scientist. "I know of no example in history with this level of mortality, killing all the animals and all the calves." The team, which has been taking soil and vegetation samples, believes the mass deaths may have been caused by a bacterial infection or by a virus carried by mosquitoes, Smithsonian reports. Whatever the culprit, it has been able to cause a staggering death toll because the population's females all have their calves in the same week, allowing disease to spread quickly, New Scientist notes. (In better news for an endangered species, the US government says most humpback whale populations have rebounded.)