The mysterious mass deaths of about 200,000 saiga antelopes in Kazakhstan last year was caused by a bacterial infection.



As news emerged in May last year of the near-total decimation of the Betpak-Dala population of saiga antelope, there was plenty of speculation but few concrete answers as to what might have been responsible.

One idea was that rainfall had resulted in widespread, mortal bloat. Perhaps there had been some infectious disease that had wiped out herd after herd. Some even blamed poisoning by toxic rocket fuel spread around Kazakhstan’s Baikonur Cosmodrome.



In the runup to this year’s breeding season, which is when the animals are at their most vulnerable to such events, the Saiga Conservation Alliance (SGA) has released the latest thinking on what caused the mass mortality in 2015. Several labs have confirmed the presence of the bacterium Pasteurella multocida in tissue samples from carcasses collected during last year’s die-off.



This pathogen normally lives harmlessly in the respiratory tract of these antelope but it appears to have run amok, resulting in hemorrhagic septicemia. This is known to occur in wild and domestic animals in grassland ecosystems, but it has never resulted in close to 100% mortality as was observed in the Betpak-Dala population. Research efforts are now concentrating on figuring out how the Pasturella could have taken over as it did.

Are there any steps that could be taken to minimise the chances of a repeat of last year? Not really, says Richard Kock of the Royal Veterinary College. “There is no practical prophylaxis possible against hemorrhagic septicemia in saiga given the species’ behaivour and the lack of a delivery mechanism for a vaccine.” If, however, there are other contributing factors that can be identified, “the potential for intervention can be reassessed” in the future, he says.

Saiga carcasses are tossed into a trailer following a similar but much smaller die-off event in 2010. Photograph: Uralskaya nedelya/Raul Uporov/Reuters

Prior to the deaths last year, the global population of saiga stood at around 262,000. The decimation of the Betpak-Dala herd means that there are now fewer than 100,000 animals in existence.

“With the saiga’s calving season just around the corner in early May, you can feel the tension mounting amongst everyone who works with this critically endangered species,” says Caryln Samuel, SCA’s administrator.