PhD in Veterinary Sciences for Animal Health and Food Safety

Contacts

Supervisor

Ezio Ferroglio

Curriculum vitae

Curriculum Vitae

Phd thesis

Background

The interface between wildlife, domestic animals, and humans is expanding across Europe, driven by climate change, agricultural policies, natural resource management, urbanization, and human population growth. These changes are leading to increased population sizes and densities of certain wild species, such as ungulates, bringing them closer to humans and domestic animals. These phenomena are boosting the circulation of zoonotic pathogens. Notably, vector-borne and tick-borne pathogens are contributing to emerging diseases due to the geographic expansion of vectors, resulting in higher disease incidence and the emergence of cases in areas where they were previously unreported.

Given this, an integrated approach to disease surveillance, encompassing wildlife, domestic animals, humans, and the environment, is crucial. Such an approach should include robust monitoring of population dynamics (e.g., density, abundance, presence/absence, and distribution). This is particularly critical for tick-borne diseases, which involve complex multi-host life cycles, necessitating coordinated surveillance efforts across different sectors.

The goal of this project is to investigate the factors influencing human exposure to tick-borne zoonoses in natural environments, with a specific focus on how wildlife and habitat characteristics affect pathogen circulation.

Preparatory work

This encompasses different aspects related to the core activity of the thesis.

1. Analysis of wildlife disease publication trends over the past 50 years reflects the growing interest of the scientific community in this field. While the volume of publications on epidemiology and vector-borne diseases has remained relatively stable, there has been a notable surge in recent years in research focusing on emerging diseases, conservation-related diseases, and topics related to surveillance and control measures. https://doi.org/10.3390/vetsci9110629

2. Studies on tick abundance gradients near human pathways indicate that tick density peaks at approximately 1 meter from the path, representing an optimal balance between microhabitat suitability and host presence. Beyond this distance, tick abundance declines, particularly for larval stages compared to nymphal stage. https://doi.org/10.3390/vetsci11100508

3. Camera traps utility to monitor wildlife in the emergency context of African Swine Fever has also expanded to estimate movement parameters and population density of species further than wild boar, including wild carnivores and ruminants. https://doi.org/10.1155/2023/7820538

4. Among various data collection methodologies, citizen science has proven to be an effective approach for estimating the density and distribution of wild animal species across different habitats. It also provides valuable information on vector-host associations in wildlife, with the potential to be integrated into One Health surveillance framework. https://doi.org/10.1017/S0031182023001038

Relating camera trap data to ticks abundance and tick-borne diseases prevalence

This section aims to integrate data on wild ungulates and mesocarnivores collected via camera traps with tick abundance and the presence of tick-borne pathogens in the same area. Interactions were modelled by incorporating environmental factors such as temperature, humidity, Normalized Difference Vegetation Index, seasonality, and altitude into the analysis of tick abundance, testing these relationships across different environmental contexts. Temporal occupancy (measured as the number of seconds a wild animal spends at a specific location) was the parameter chosen to examine the association between wildlife presence and tick abundance. Being Ixodes ricinus the most prevalent tick species in the study, the results revealed a general bell-shaped relationship, with a trend towards additive effect for species like mesocarnivores and deer, common hosts for I. ricinus, and towards a detractive effect for wild boar, which is rarely parasitized by this tick species. https://doi.org/10.1155/2024/4064855

This relationship varied across different habitats and wildlife population densities, with altitude acting as a limiting factor in tick abundance. https://doi.org/10.3390/ani14182749

Regarding tick-borne pathogens, the presence of Babesia divergens, Babesia microti-like, Borrelia burgdorferi sensu lato, and Spotted Fever Group Rickettsiae was modelled on the individual counts of targeted wild species from camera traps. Although these species are not reservoirs for the pathogens of interest, their monitoring and management are straightforward, underscoring the value of camera trap data in assessing the risk of tick-borne pathogen transmission.

Expanding the interface: the human side

In collaboration with infectious disease specialists from Ospedale Amedeo di Savoia, we sampled several groups of individuals with varying occupational or recreational exposure to tick bites through outdoor activities. The targeted pathogens included Babesia divergens, Babesia microti-like organisms, Babesia venatorum, Borrelia burgdorferi sensu lato, Spotted Fever Group Rickettsiae, and Anaplasmataceae. Seroprevalence levels were relatively consistent across groups, while DNA detection through PCR revealed higher prevalence rates in professionally exposed groups. The risk of tick exposure increased for those engaged in outdoor work or leisure activities, and adopting preventive measures showed protective effects.

In a subset of participants from the same rural area, we also assessed pathogen prevalence in questing ticks, culled wildlife, and domestic dogs from the same region, to compare prevalences. The results revealed differences reflecting variations in the pathogen's lifecycle and host associations.

Research activities

My research focuses on a holistic approach to studying the circulation of parasites and tick-borne diseases at the human-wildlife-livestock interface, with a particular focus on disease ecology.

In addition to the research activity presented in my thesis, I also had the opportunity to investigate:

• With the tick data collected in my thesis, the relationship with wild ungulates density implementing geostatistical analysis (abroad period at Lancaster University, UK)
• Relationship between Toxoplasma gondii seroprevalence in game animals and spatial/demographic characteristics such as wild boar density, red fox density, human density and distance from the human settlments
• Integrating data from different sources (official surveillance, scientific literature and open sources) to assess sensitivity of surveillance systems (abroad period/internship at World Organization of Animal Health, Paris)
• Bush animals zoonotic pathogens transmissible to humans through incorrect carcasses handling (collaboration with CIFOR, Cameroun)

Moreover, I have collaborated to the activities of the ENETWILD Consortium, a network of scientists across Europe dedicated to enhancing European capabilities in monitoring wildlife
health under the One Health approach.

Publications

All of my research products