Reviewing the Ecological Evidence-Base for Management of Emerging Tropical Zoonoses: Kyasanur Forest Disease in India as A Case Study
Authors: Burthe Sarah J , Schäfer Stefanie M. , Asaaga Festus A. , Balakrishnan Natrajan , Chanda Mohammed Mudasssar , Darshan Narayanaswamy , Hoti Subhash L. , Kiran Shivani K. , Seshadri Tanya , Srin Prashanth N. , Vanak Abi T. , Purse Bethan V. 
Published: June 2020

Background Zoonotic diseases disproportionately affect poor tropical communities. Transmission dynamics of zoonoses are complex, involving communities of vector and animal hosts, with human behaviour and ecosystem use altering exposure to infected vectors and hosts. This complexity means that efforts to manage and prevent human spillover are often hampered by a poor ecological evidence base and intervention strategies tend to focus on humans (e.g. vaccination, preventative drug treatment). However, integrating ecological and evolutionary understanding of multi-vector and host transmission, human and environmental factors into disease control policy is essential. Recent frameworks have been developed to guide appropriate design of “ecological interventions” which have the potential for being more long-term, effective and economical approaches to managing human disease.Results We extended new frameworks to identify the hierarchical series of barriers that need to be overcome by a vector-borne pathogen to facilitate human spillover, focusing on an emerging, tick-borne zoonotic pathogen in India, Kyasanur Forest Disease Virus (KFDV). Current management recommendations focus on human barriers, through personal protection and vaccination, as well as targeting vector control on cattle and at the sites of monkey deaths. Assessment of the validity of current management practices for KFD through literature review and interviews with disease managers found the efficacy of interventions difficult to quantify, due to poor empirical evidence and a lack of understanding of KFDV-vector-host ecology, particularly regarding the role of cattle in amplifying tick populations and the spatial scale of risk arising from ticks infected via monkeys, which are considered to be amplifying hosts for KFDV. The spraying of malathion around dead monkeys and the burning of vegetation to reduce tick abundance were particularly unfounded interventions. The need for community guidance and education in best practice for tick-prevention and improved vaccine efficacy and surveillance were also identified. We highlight 18 urgent research priorities and identify those which could refine current management strategies or facilitate ecological interventions targeting vectors and host barriers to spillover in the future. Conclusions We emphasise that inter-disciplinary One Health approaches involving collaboration across diverse disciplines including ecology, epidemiology, animal and public health, health systems and social sciences, and with meaningful involvement of local communities, are necessary to refine predictive models of spillover, develop new interventions and target vaccination strategies and surveillance more effectively. Applying such approaches to understand the complex ecological systems involved in zoonotic spillover, and refine and develop appropriate management interventions, including ecological interventions targeting non-human barriers, will ultimately lead to more sustainable and long-term reductions in human cases of neglected zoonoses in the future.