Update by Steffen Zuther, ACBK, published in Saiga News Issue 20, on page 8.

As mentioned in Saiga News 19, in mid-May 2015 the beginning of a mass die-off was detected in the biggest calving aggregation of the Betpak-Dala population, in the south of Kostanay oblast, Kazakhstan. The die-off lasted for almost a month and affected all the bigger calving aggregations throughout the range of the population. The veterinary services started to investigate the outbreak immediately, to collect the samples needed for laboratory analysis and to bury the carcasses.

The authorities, under the leadership of the Committee of Forestry and Hunting of the Ministry of Agriculture, made enormous efforts to get the required human and technical capacity to the remote mass die-off sites. In the end, 150,044 carcasses were buried, but many more are thought to be spread across a wide area of the steppe, which probably significantly increases the number of dead animals.

As part of the Altyn Dala Conservation Initiative, a team from the Association for the Conservation of Biodiversity of Kazakhstan (ACBK) was at the main die-off site almost from the very beginning, together with a student from the Royal Veterinary College London (RVC). Originally the team was intending to study calving, as they had done in previous years. However, carcasses were already apparent on the first day, and the task of documenting the symptoms of affected saiga soon became our main focus, as the die-off progressed. The presence of the team from the earliest days of the outbreak allowed us to collect quite a lot of observations of affected animals and to support veterinarians in their investigation of carcasses and their sampling. This was mainly done in collaboration with experts from the Research Institute of Biological Safety Problems (RIBSP), which has been a partner of ACBK and RVC since 2012.

Saiga antelope affected by the syndrome were extremely weak and depressed, lost the ability to move normally and could not hold their heads up. At some point during the progress of the syndrome, they would just lie down on the ground and not get up any more if left undisturbed. Increasing diarrhoea was observed in these animals, as well as salivation from the mouth and in some cases secretions from the nose. The body was not bloated though, which had been observed in other incidents in 2010 and 2011 (see Saiga News Issues 11,12 and 13). Breathing became harder and harder for them, they lost the ability to get up, and finally died. All these stages lasted for only a few hours and were documented thoroughly.

An expert mission supported by the Convention on Migratory Species (CMS), the Altyn Dala Conservation Initiative and the Ministry of Agriculture of Kazakhstan was conducted towards the end of May to another die-off site in Akmola province, further north. Veterinary experts from the RVC, FAO, and RIBSP necropsied several animals. As a preliminary diagnosis, hemorrhagic septicaemia was identified, also based on the first laboratory results, which revealed the presence of the bacterium Pasteurella multocida, serotype B, which is thought to be the main pathogen behind the die-off. Opportunistic infection with this bacterium has been confirmed by several laboratories. But traces of Clostridia perfringens were also found. All experts agree that the toxins from these bacteria caused the die-off, but it is not clear yet what triggered the outbreak.

Several investigations have been started to solve this question. The Ministry of Agriculture has established a special working group consisting of various specialists in veterinary science and saiga ecology, in order to discuss the findings, make conclusions about the die-off and determine the next steps. By the end of June, another expedition took place, organised by ACBK with support from "Okhotzooprom" State Enterprise, crossing the habitat of the Betpak-Dala saiga population from its wintering areas to calving grounds.

The aim was to investigate the ecosystems which were used by saigas this year prior to the die-off, in order to identify any abnormalities and find potential causes for Pasteurella becoming virulent. Numerous samples of soil, plants and water were collected for laboratory analyses. Livestock in the region were investigated to detect any diseases which could have been transmitted to saiga. Interviews with livestock owners allowed conclusions to be drawn about previous diseases and their potential effects for saiga. However, although disease was discovered at a few places, no link to the saiga mass die-off could be established.

An investigation of the vegetation along the migration routes and at the die-off sites did not show any unusual abundance of poisonous plants. There were completely different vegetation communities at the various die-off sites. This makes an exclusive causal role of plants in the die-off less likely, but there might still be a role for particular plants in combination with other environmental variables. The samples of soil, water and plants have partly been analysed and did not reveal any remains of toxic rocket fuel, which had been suspected to be the main cause in the public media.

Further laboratory investigations of blood samples from dead saigas in European laboratories have not found any infectious disease so far. But analyses are continuing, as well as a complete histopathological analysis of tissue samples from the dead saigas.

On the international level, an interdisciplinary research group under the leadership of the Royal Veterinary College in London is aiming to shed light on the triggers behind this extraordinary die-off event. The strategy is to conduct a comprehensive analysis of all the existing material, do a retrospective analysis of similar die-offs in saigas and other species in the past to identify characteristic patterns, to gather additional data through further fieldwork, and to support the government of Kazakhstan in elaborating quality strategies and policies. This project is funded by the UK government's Natural Environment Research Council and will continue until summer 2016.

These efforts are furthermore supported by the Wildlife Conservation Network, the People's Trust for Endangered Species, Fauna and Flora International, the Saiga Conservation Alliance, Frankfurt Zoological Society and the Royal Society for the Protection of Birds.

At the same time, the government of Kazakhstan is preparing a research programme and action plan for future years, in order to carry out high quality research especially on saiga ecology and health and prevent such die-offs in the future. Various institutions and experts from Kazakhstan and internationally are contributing to this process, which is supposed to be finished in the near future.