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Tick-borne Diseases and Mongolian Reindeer Conservation

December 9, 2009

What's New Image Editor's note: Morris Animal Foundation has funded a fellowship for Dr. Sophia Papageorgiou, a veterinary scientist in the School of Veterinary Medicine. She is investigating risks to the health of reindeer in Mongolia due to tick-borne infections and tells about her work below. See related story. 


Reindeer (Rangifer tarandus) and caribou are linked intimately with nomadic herding cultures within taiga and tundra ecosystems in the northern hemisphere, generally north of the 50th parallel, and these animals migrate extensively within this range. There are over 2 million domesticated reindeer currently maintained by Norwegian, Swedish, Russian/Siberian, and Mongolian indigenous peoples, as well as numerous tribes in northern North America that rely on caribou for their subsistence.

Reindeer and caribou remains, unearthed from human prehistoric camps and dated at 9,000 to 16,000 BCE, indicate reindeer provided food and fiber for indigenous cultures and that domestication of reindeer for use as food (milk and meat), fiber, transportation, and pack animals occurred at least 3,000 years ago. In north central Mongolia, petroglyphs (stone etchings) of reindeer and herders dated at approximately 3,000 years old reveal that reindeer herding cultures resided in southern Siberia and northern Mongolia for millennia, though these animals were hunted prior to domestication for hundreds of thousands of years. 

The Mongolian Tsaatan (people of the deer) reindeer herding community historically migrated to and from northern Mongolia and southern Siberia. In the early 1900s Mongolian reindeer herders were isolated from their historical migratory routes when the Mongolia-Siberia border was closed at the time the Mongolian People's Revolutionary Party was established.

The Tsaatan, a semi-nomadic reindeer herding culture, migrate solely in this smaller taiga ecosystem within Mongolian borders. This group is the southern-most reindeer-herding community in the world. The environment of the Tsaatan may be altered by climatic shifts, with subsequent landscape changes and disease emergence. 


Challenges to the Mongolian reindeer population include availability of consistent veterinary care in the remote taiga region, influx of miners, hunters, and loggers eroding the fragile taiga ecosystem, and emergence of infectious pathogens such as Lyme disease and brucellosis in the reindeer. The far northern ecosystems have been experiencing warming climatic trends in the past two decades, with global warming linked to calf mortality in caribou. The increasing temperatures and changes in the length and intensity of these climatic shifts in arctic and subarctic regions may generate a cascade of events with subsequent impacts on reindeer health, forage availability, and diversity, abundance, and density of tick and reservoir host populations, that may contribute to emergence of tick-transmitted pathogens. 


Reindeer in Mongolia are compromised in health, with low body condition scores, musculo-skeletal problems that include lameness and joint effusions, and problems with effective reproduction in the herds that may be attributed to tick-borne diseases and brucellosis.

Contributions to these health concerns likely include genetic, nutritional, and infectious factors. One important aspect of Mongolian reindeer health that has received minimal attention is infectious disease.  For my PhD, I reported the first identification of a suite of three tick-borne pathogens in Mongolian reindeer. Identifying the tick species and reservoir host mammals that transmit the pathogens documented in my PhD research, and researching brucellosis in these animals, is the focus of the post-doctoral work generously funded by the Morris Foundation, and is the next step in elucidating disease transmission cycles in this isolated, unique taiga ecosystem.


  • Reindeer are the only deer where the males, females, and even young calves, sprout and grow antlers. These antlers are shed and new sets grow annually. 
  • Female reindeer generally give birth to only one calf in the spring. 
  • Domesticated reindeer in the world number 2 million, and there are approximately 3 million wild caribou.
  • Reindeer have thick fur coats with hollow hair fibers that insulate and trap air to maintain warmth and facilitate thermoregulation like other arctic species, such as polar bears. 
  • Reindeer can swim and do so even in cold, icy water. 
  • Specialized redundant nasal passages to help circulate and warm the incoming air before it reaches the lungs and decrease loss of heat when breathing. 
  • A circulatory system that shunts blood from their extremities to their body core when they sleep to conserve body energy and heat.
  • Reindeer survive the winter which offers sparse forage throughout their range by subsisting on lichen unearthed from snow and ice by digging with their hooves.
  • Hooves that undergo seasonal physical changes in fall/winter when the footpads harden and shrink to accommodate moving and digging on ice in contrast to spring/summer when the hooves soften and expand to help the deer maintain traction and navigate boggy taiga landscapes. 
  • Mongolia currently has only about 800 reindeer in this hunter-gathering and herding subsistence community. 
  • Domesticated reindeer are quite docile and easy to handle.
  • Some reindeer herding cultures believe that their spirits are reindeer that fly in the sky, hence stories of Santa and flying reindeer. 

  Watch a video about Mongolian reindeer from NBC: