Saigas on the brink: Multidisciplinary analysis of the factors influencing mass mortality events

Abstract

An opportunistic bacterial infection preceded by weather of unusually high humidity and temperature caused mass death of saigas.

Mass Die-Off of Saiga Antelopes, Kazakhstan, 2015

“…The mass die-off in Kazakhstan and the small population of ≈10,000 in Mongolia recently devastated by peste des petits ruminants (PPR) virus in 2017 illustrates this point ( 3 ). The saiga antelopes undertake large-scale seasonal migrations between their summer and winter ranges because of the extreme variation in climate conditions and the need for pastures offering sufficient forage.…”

“…The first dead animals were detected in the Amangeldy District (Kostanay region) of Kazakhstan on May 10, 2015, and additional die-offs were recorded in unconnected discrete locations in the Aktobe and Akmola regions ( 3 ). A primary diagnosis of hemorrhagic septicemia as the cause of death was proposed at the sites on the basis of clinical signs and gross pathology.…”

“…Although these samples were from a region 175 km from the site where the FTA card samples were taken, they were considered part of the same saiga antelope population. Given the uniformity of the clinical syndrome and consistency of the pathogenesis, the sample of cases selected was small relative to the scale of the die-off, but each case was evaluated in considerable depth and considered representative of the affected population on the basis of the consistent pathology and disease characteristics observed in all the affected animals ( 3 ). …”

“…Annual disease monitoring in saiga antelopes had been established after die-offs occurred in western Kazakhstan in 2010, and an international multidisciplinary research team was on the ground at the time of the die-off, performing routine surveillance ( 3 , 4 ). …”

“…Laboratory results on the microbiologic, pathologic, and environmental conditions at the time of the 2015 outbreak suggested hemorrhagic septicemia caused by Pasteurella multocida serotype B and triggered by environmental conditions ( 3 , 6 ). However, whether a second unknown infectious agent had predisposed the animals to infection with P. multocida was unclear from the laboratory results.…”