Research on ticks and tick-borne diseases at the University of Antwerp
In 2006 the Evolutionary Ecology Group led by Erik Matthysen started a research programme on host-parasite interactions using bird ticks as a model. The programme started with a PhD project by Dieter Heylen (2006-2012), who continued to extend the research as postdoc (2012-2018) and co-supervises ongoing projects to this day as Marie Curie fellow based in Princeton (US). Over the years the research was extended to include transmission of tick-borne diseases as well as ecology of generalist ticks. The project led to several additional PhD projects by Raoul van Oosten (2012-2015), Gerardo Fracasso (2017-), Mats Van Gestel (2018-) and Käthe Robert (2020-) as well as multiple (international) collaborations including RIVM (Netherlands), CEES (Norway), Univ Coimbra (Portugal), Univ Cornell (US) and Univ Ghent (Belgium) and participation in the INTERREG project "NorthTick" (2019-2023).
One of the first discoveries was that the nestbox-breeding birds we use as model (great tit Parus major, blue tit Cyanistes caeruleus) are regularly infested by three different tick species, each with a different ecology and host specialization: the common generalist tick Ixodes ricinus, the little studied bird tick Ixodes frontalis, and the highly specialized tree-hole tick Ixodes arboricola. The latter appears to largely depend on great and blue tits as hosts. We developed a methodology to infest birds experimentally in the field and in the lab, with ticks surviving and moulting in the lab in between feeding episodes. Given the extremely low impact of the ticks on the birds' health, this model system allowed us to answer a large number of questions with respect to life-history and behaviour of different tick species, and transmission of pathogens. Diagnosis of pathogens in previous and ongoing projects is carried out by an expert centre led by Hein Sprong (RIVM, Netherlands). All experiments are fully licensed by the University's Ethical Committee and the Flemish Agency for Nature and Forest. Among others, the following questions have been studied:
- What is the impact of ticks on health and condition of songbird hosts, and do hosts develop resistance to tick feeding?
- What are the specific adaptations to the nidicolous lifestyle of Ixodes arboricola, compared to the generalist Ixodes ricinus?
- How do sympatrick tick species differ in seasonal activity and host use (e.g. adults vs. nestlings)?
- Which factors drive host specificity of ticks?
- How are tick populations genetically structured?
- Is tick feeding success on hosts density-dependent?
- Which pathogen communities (notably Borrelia s.l.) exist in different tick species feeding on the same bird hosts?
- Are bird ticks competent vectors for Borrelia genospecies?
- Is there consistent and heritable among-individual variation in tick traits (life-history, size, hypostome morphology) and how does this relate to parasite success? (PhD Gerardo Fracasso)
In a second stage the research has been broadened to the ecology and zoönotic risk of the generalist tick Ixodes ricinus, fitting more closely to one of the main overall research themes of the research group (ecology of infectious diseases). This is made possible by a close collaboration with the group of Kris Verheyen (University of Gent) and again Hein Sprong at RIVM, as well as interactions with stakeholders in public health and forest management. The PhD of Sanne Ruyts (Univ Gent, 2017, co-supervised by Matthysen) explored the link between forest management, host communities and pathogen communities in ticks. Mats Van Gestel (PhD 2018-) studies fine-scale distribution of questing ticks in forested areas and link this to the distribution of hosts for larvae, with the ultimate aim of improving tick-related management of recreational sites. We also collected pilot data on distribution of tick hosts, ticks and pathogens along an urbanization gradient in and around the city of Antwerp. In 2020 a citizen science project will be developed on distribution of ticks and hosts in private gardens, as part of the INTERREG project NorthTick.