Towards improved understanding and management of parasite transmission in the rangelands of Asia

Abstract

Rangelands are co-grazed by domestic and wild ungulates, potentially leading to disease transmission, which is complicated by climate change and altering livestock management. Gastro-intestinal nematodes (GINs) are key determinants of ungulate health. I investigated the impacts of environmental and social factors on GIN cross-transmission between ungulates in the temperate and montane Asian rangelands - a relatively data-poor system, with limited scientific-veterinary infrastructure. First, I built an iterative framework, demonstrating the value of combining ecological and social information to inform disease management. Subsequently, I worked in three areas shared by wild and domestic ungulate hosts. In India, the montane rangeland of Kibber is home to sedentary Bharal Pseudois nayaur and livestock, while Pin has sedentary Ibex Capra sibirica and migratory livestock. The temperate rangeland of Ural, Kazakhstan is home to migratory saigas and sedentary livestock. I conducted fieldwork in each place and developed GIN transmission models, building from simpler to more complex systems and methods. In Kibber, gradual accumulation of infective GIN larvae over summer governed pasture infectivity. The most effective intervention was early-season suppression of GIN infection in livestock using temperature cues. In Pin, I highlighted the importance of social factors affecting GIN transmission and found that a c.30 day intervention before the migratory livestock leave Pin achieved the highest infection attenuation. In Ural, I examined interconnections between multi-scale social-ecological factors affecting ungulate health. Then, I modelled parasite transmission, likely future changes, and evaluated parasite reduction interventions. Increased livestock, but not climate change, resulted in increased infection for saigas. Early-season suppression of infection in livestock reduced predicted parasite loads in saigas. Working on a similar goal across three sites revealed contextualising parasite transmission models in an interdisciplinary understanding of local socio-ecological systems is key. The thesis provides a scientific foundation for aligning herder livelihoods with wildlife conservation.

Date of Award	12 May 2022
Original language	English
Awarding Institution	University of Bristol
Supervisor	Richard Wall (Supervisor), Eric Morgan (Supervisor) & E.J. Milner-Gulland (Supervisor)