Zoonoses disproportionately affect tropical communities and are associated with human modification and use of ecosystems. Effective management is hampered by poor ecological understanding of disease transmission and often focuses on human vaccination or treatment. Better ecological understanding of multi-vector and multi-host transmission, social and environmental factors altering human exposure, might enable a broader suite of management options. Options may include “ecological interventions” that target vectors or hosts and require good knowledge of underlying transmission processes, which may be more effective, economical, and long lasting than conventional approaches. New frameworks identify the hierarchical series of barriers that a pathogen needs to overcome before human spillover occurs and demonstrate how ecological interventions may strengthen these barriers and complement human-focused disease control. We extend these frameworks for vector-borne zoonoses, focusing on Kyasanur Forest Disease Virus (KFDV), a tick-borne, neglected zoonosis affecting poor forest communities in India, involving complex communities of tick and host species. We identify the hierarchical barriers to pathogen transmission targeted by existing management. We show that existing interventions mainly focus on human barriers (via personal protection and vaccination) or at barriers relating to Kyasanur Forest Disease (KFD) vectors (tick control on cattle and at the sites of host (monkey) deaths). We review the validity of existing management guidance for KFD through literature review and interviews with disease managers. Efficacy of interventions was difficult to quantify due to poor empirical understanding of KFDV–vector–host ecology, particularly the role of cattle and monkeys in the disease transmission cycle. Cattle are hypothesised to amplify tick populations. Monkeys may act as sentinels of human infection or are hypothesised to act as amplifying hosts for KFDV, but the spatial scale of risk arising from ticks infected via monkeys versus small mammal reservoirs is unclear. We identified 19 urgent research priorities for refinement of current management strategies or development of ecological interventions targeting vectors and host barriers to prevent disease spillover in the future.

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.

Dengue fever (DF) or dengue haemorrhagic fever (DHF) has not previously been reported in Coimbatore and Erode districts in Tamil Nadu in India. In 1998, 20 hospitalized cases of fever tested positive for dengue virus IgM and/or IgG antibodies. All of them had dengue-compatible illness, and at least four had DHF. Two of them died. Sixteen cases were below 10 years of age. The cases were scattered in 15 distantly located villages and 5 urban localities that had a high Aedes aegypti population. Although the incidence of dengue-like illness has not increased recently, almost 89% (95/107) of samples from healthy persons in the community tested positive for dengue IgG antibodies. The study showed that dengue has been endemic in the area, but was not suspected earlier. A strong laboratory-based surveillance system is essential to monitor and control DF/DHF.

The Nilgiri hills and adjoining downhill areas provide favourable ecological conditions for the propagation of haematophagous arthropods owing to richness in vegetation and animal activities. A study has been undertaken during 2008–2010 on the distribution and abundance of ticks of domestic animals in seven different biotopes. A total of 3,008 domestic animals were examined in areas ranging from an altitude of 300 to 2200 meters above mean sea level (MSL) of which 1,335 (44.5%) animals were having tick infestation. A total of 6,012 adult and immature ticks belonging to 12 species (11 ixodid and one argasid) were collected. Eleven tick species were collected from Kallar area situated downhill eastern slopes of the Nilgiris followed by Burliar area (7 species) located at higher altitudes. From Masinagudi area near to dense forests and scrub jungles, five species were recorded. However, at higher elevations on the hills, Udhagamandalam area, only one species was recorded. Among various tick species recorded in the study,Boophilus micropluswas distributed in almost all areas surveyed followed byHaemaphysalis spinigeraandRhipicephalus sanguineus. The factors governing their distribution and epidemiological significance in the transmission of various tick-borne diseases of public health importance are discussed.

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