Saiga antelope (Saiga tatarica tatarica) mortality in Kazakhstan 2015: emergency investigation of disease outbreak to improve knowledge of drivers

点击翻译按钮获取中文摘要

Catastrophic disease events can be devastating for the survival of threatened species, and can reverse years of conservation effort. When populations are already small and vulnerable, due to poaching or habitat loss, disease can be the final straw. Examples of disease as a conservation issue include the Ethiopian wolf, which is susceptible to distemper and rabies from domestic dogs, and rinderpest, which decimated the wild and domestic ungulate populations of Africa in the 19th century. Recently it has been recognised that disease is best understood and tackled in a wider context than just the individual species of host and pathogen; resilient ecosystems are better able to accommodate disease outbreaks, and human-caused environmental change can make species more vulnerable.The saiga antelope is a migratory ungulate which gathers to give birth in large aggregations. It is critically endangered due to a >95% decline in population size over <10 years due to poaching for its horns and meat. However one population (Betpak-dala) has recovered well, to about 250,000 individuals in April 2015. Mass die-offs from disease occur regularly in this species, but the causes and contributing factors have never been properly investigated. In May 2015, 120,000 saigas died within a few days in the Betpak-dala population, about half this population, and >1/3 of the global population. For the first time, a rapid response team was able to attend and collect samples from the affected saigas and their environment. Initial observations suggest that the deaths were a result of a complex interaction between particular environmental conditions (wet weather, lush grass) and the weakness of females which had just given birth, causing pathogens which were present but latent within the saigas to take hold. This is not the whole story, however, which may also include toxins in plants or water, an insect-carried disease, or a directly-transmitted virus.In this project, we will analyse the already-collected samples to diagnose the causes of and contributing factors to this mass die-off. We will run an urgent mission to the field, to collect supplementary information which will help us to home in on the triggers for this disease. We will visit both affected and unaffected areas, to understand what the differences are. We will talk to local herders, and get weather records for the days leading up to the deaths. Next, we will compile everything we know about this outbreak, and about previous outbreaks (recent and historical, in saigas and similar species), to get an overall picture of the pattern of events and environmental conditions which leads to mass saiga deaths. Combining this understanding with projections of future environmental conditions (e.g. climate change) and emerging infectious diseases (e.g. peste des petits ruminants, which is entering Central Asia from Africa), we will explore scenarios of risk from a range of diseases to both saigas and livestock, and how risks could be mitigated (e.g. through vaccination or changes in land use practices).Having assembled this evidence, we will help the Government of Kazakhstan to prepare for future disease outbreaks; we will design surveillance protocols so they can have early warning of potential triggers for mortality, and help them to examine whether, and which, interventions might reduce the risk of outbreaks, or mitigate them. We will run a technical workshop at the upcoming meeting of the UN Convention on Migratory Species' Memorandum of Understanding on saiga conservation, and support signatories (governments and NGOs) to develop and ratify an action plan.This project is a unique chance to investigate a dramatic and complex disease event of huge conservation importance, which will also shed light on the relationship between environmental change and disease. This makes it of wide general interest for ecologists, and an opportunity which it is vital to take while there is still time to act.