From a Friend to a Foe
Just like us, saigas have bacteria and other microbes living in their gut and respiratory tract. These microorganisms critically affect the host health in many ways. Often times these effects are positive or even inevitable. For example, the development of our immune system is highly dependent on microbes. However, being very fast evolving creatures, these microbes also represent a potential threat to the host.
The big saiga mass mortality in 2015 (and at least one other big saiga mortality event) was caused by the outgrowth of a bacterium called Pasteurella multocida (1). Normally, this bacterium lives harmlessly in the upper respiratory tract of healthy saigas (2). However, exploration of the dead saigas in 2015 revealed that this microbe had managed to escape from the respiratory tract to other tissues including blood, milk, liver, and spleen. The animals had eventually died from blood poisoning caused by this bacterium.
It appears that (human-driven) climate change has a role in the outgrowth of this bacterium and hence in the saiga mass mortalities because higher humidity and temperature have been observed in the days leading to the mass mortalities caused by P. multocida (1). However, we still don’t know how these environmental changes allow the bacterium to turn from a friend to a foe.
It has been shown that Clostridium difficile found in the human gut microbiota manages to cause an infection when Clostridium scindens levels are reduced by antibiotics (3). Similar ‘community changes’ could be happening in the saiga microbiota. These could be caused directly or indirectly by external factors, such as weather conditions. To this date, we know very little about the saiga microbiota and its role in the mass mortalities.
There is not much time left, so please help us initiate the exploration of the mysterious saiga microbiota and make a pledge and share our campaign to your friends and colleagues today. Your help is very much appreciated!
References
1. Kock, R. A. et al. Saigas on the brink: Multidisciplinary analysis of the factors influencing mass mortality events. Sci. Adv.4,eaao2314 (2018).
2. Sanchez-Monge, F. Calving status and commensalism of Pasteurella multocida in the surviving Betpak-dala saiga population in May 2016, after a mass mortality event in May 2015. Thesis, R. Vet. Coll.(2016).
3. Buffie, C. G. et al.Precision microbiome reconstitution restores bile acid mediated resistance to Clostridium difficile. Nature517,205–208 (2015).
Microbiota refers to the collection of microbes living in a particular site, such as the gastrointestinal tract
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