Ecology of Borrelia garinii infections in wild birds

PhD Student opportunities:

* we welcome candidates who are eager in pursuing the link between bird infections (with ticks and with tick-borne pathogens, notably Borrelia garinii) and bird behaviour (personality, habitat use, reproductive investment). Data on infections will be provided by the project described below, thus the focus of this project will be on behavioural aspects. Candidates are expected to submit an application for external funding with the FWO research council by 1st March 2023, and if positively evaluated, can start on 1st November 2023. We offer assistance in conceiving and writing the application but cannot guarantee funding. If you are interested, contact

A crucial factor to predict the persistence and spread of infections in natural systems (and potential spill-over to humans) is the capacity of so-called reservoir hosts to maintain the infection and transmit it to others. This is known to vary greatly between species, but also within species and through time, although this part of the variation is often less well understood. In this project we focus on between- and within-individual variation in infectiousness in a natural population, using a bird-tick-Borrelia system as model. Great tits are among the most important reservoirs of Borrelia garinii, one of the main causal agents of Lyme disease.

We will study how the capacity of birds to transmit these bacteria to feeding ticks varies between individuals, how it varies through the annual cycle, and whether stressful episodes may reactivate infections in birds that previously were not infective. We will do this in a well-studied population of great tits where individuals can be captured repeatedly and additional information is available on their breeding, survival and physiological condition. This allows us to repeatedly test infectiousness of the same individuals and relate this to their age, sex, condition and other factors. Infectiousness is tested by xenodiagnosis, i.e. allowing pathogen-free larval ticks to feed on birds and subsequently examine infections in ticks by molecular screening. We will also keep a small number of birds in captivity to study year-round variation in infectiousness in standard conditions. We will challenge birds with moderate stress levels of ecological relevance (e.g. variation in food quality, or brood size). Ultimately we will study how temporal and individual variation affects the basic reproduction number R0 of the infection in nature. 

This project is funded by the FWO-Flanders under the title “Drivers of individual and temporal variation in host infectiousness: a bird-specific Borrelia as a model system”.

Project supervisors: Prof. Erik Matthysen, Dr. Dieter Heylen, Dr. Hein Sprong (RIVM-NL).

People involved: Jens Zarka (PhD student), Sophie Philtjens (technical assistance).

For more information, contact

Duration: 1/1/2022 – 31/12/2025

More information on tick-related research at EVECO.

Prior publications relevant to this project:

Heylen  D, Tijsse E, Fonville M, Matthysen E, Sprong H. 2013. Transmission dynamics of Borrelia burgdorferi s.l. in a bird tick community. Environmental Microbiology, 15: 663-673.

Heylen  DJA, Matthysen E, Fonville M, Sprong H. 2014. Songbirds as general transmitters but selective amplifiers of Borrelia burgdorferi sensu lato genotypes in Ixodes rinicus ticks. Environmental Microbiology 16: 2859-2868.

Heylen, D.J.A. 2016. Ecological interactions between songbirds, ticks, and Borrelia burgdorferi s.l. in Europe. In: Ecology and prevention of Lyme borreliosis (Braks M.A.H. et al., eds.). Wageningen Academic Publishers, pp. 91-101.

Heylen, D., Krawczyk, A., de Carvalho, I.L., Nuncio, M.S., Sprong, H. & Norte, A.C. (2017). Bridging of cryptic Borrelia cycles in European songbirds. Environmental Microbiology, 19, 1857-1867.

Norte AC, Lopes de Carvalho I, Núncio MS, Araújo PM, Matthysen E, Ramos JA, Sprong H & Heylen D. 2020. Getting under the birds’ skin: tissue tropism of Borrelia burgdorferi s.l. in naturally and experimentally infected avian hosts. Microbial Ecology 79: 756-769