Surveillance and Epidemiology of Tick-borne Pathogens in Mongolian Ungulates

Pathogens transmitted by ixodid tick species are important health threats to agricultural animals. Borrelia and Rickettsia species tick-borne pathogens (TBPs) are well-researched in Europe, North America, and Russia although little is known about their status in Mongolia.;This cross-sectional field investigation identified TBPs in Mongolian ungulates: two populations of free-ranging reindeer (Rangifer tarandus ), living within a taiga ecosystem in Khuvsgul province (aimag) at the northern tip of Mongolia, and domesticated livestock in two aimags, Khuvsgul and Khenti, along the Mongolian-Siberian border.;Poor body condition and musculo-skeletal disorders are common in these reindeer which receive minimal veterinary care. Furthermore, livestock species have been introduced in one section of the taiga which may be adversely impacting reindeer health and the taiga landscape. Most livestock, sampled from grassland (GS) and grassland-forest steppe (GFS) landscapes, appeared in better health than the reindeer. Factors examined for association with TBP exposure included gender, age, body condition score (BCS), and taiga region for the reindeer, and species, BCS, elevation, and gender for the livestock.;One-hundred twenty-seven and 460 blood samples were collected from a total of 29 reindeer herds and eight livestock herds, respectively. These samples were tested using serology and PCR to identify Borrelia burgdorferi sensu lato (s.l.), Anaplasma phagocytophilum, Rickettsia spp., and A. ovis in these ungulates. Tick-borne pathogen prevalence in reindeer ranged from 35.4% to 51.4% for Borrelia burgdorferi s.l., 50.0% to 100% for Anaplasma phagocytophilum , and 27.5% to 76.9% for Rickettsia spp. across the west and east taiga regions sampled during 2007 and 2008.;Khuvsgul livestock had high prevalence to B. burgdorferis.l, (25%), A. phagocytophilum (64%), and A. ovis (77%), while 48% of Khenti livestock were positive for Rickettsia species (48%). When associations of gender and prevalence among livestock were compared, females and intact males had higher prevalence to A. phagocytophilum than castrated males. A higher prevalence of A. phagocytophilum was identified in small ruminants when contrasted with cattle and horses. There were interactions detected between body condition score (BCS), elevation, and outcome for three of the TBPs investigated. A. ovis prevalence measured using PCR was over 55% and 33% in reindeer and livestock, respectively.;In Khuvsgul, associations of TBP prevalence in nomadic Mongolian reindeer and pastoral livestock herds, living in adjacent regions, were evaluated using landscape type, herder, and herder management. A. phagocytophilum prevalence was higher among reindeer in the east than the west taiga. Goats within the east GFS also had higher prevalence of A. phagocytophilum compared to goats in the west GFS. A spatial analytic approach was incorporated into the analyses that evaluated spatial relationships of TBPs in two different landscapes, taiga and GFS. The conclusions from this analysis were that TBP exposure is: (1) primarily focused in or near the taiga landscape; and (2) higher in reindeer herds migrating close to the taiga-GFS ecotone region with the exception of A. ovis which was higher in west GFS small ruminants.;The Mongolian taiga is impacted by changes in landscape from overgrazing and introduced species. These factors may alter diversity and richness of taiga animal species and subsequently alter TBP disease ecology that may affect Mongolian reindeer health.;Climatic changes affect vegetation, with subsequent changes in mammal and tick populations that may also result in TBP emergence; however, both herd management and climatic changes may be affecting TBP dynamics in northern Khuvsgul. If climate change is playing a role in TBP emergence, these changes may have important implications for reindeer health and reindeer herding cultures migrating north of Mongolia in Siberian Russia. If warming patterns persist along a northern latitudinal gradient, the Tsaatan may be the sentinel community for monitoring reindeer health, TBP emergence, and effects of climate and landscape change on reindeer health in taiga ecosystems globally.