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Voordouw, Maarten

Nom
Voordouw, Maarten
Affiliation principale
Fonction
Ancien.ne collaborteur.trice
Identifiants
https://libra.unine.ch/handle/123456789/375
_
0000-0001-9384-0436

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  • Publication
    Accès libre
    Serological signature of tick-borne pathogens in Scandinavian brown bears over two decades
    (2015-7-28)
    Paillard, Lye 
    ;
    Jones, Krista L.
    ;
    Evans, Alina L.
    ;
    Jacquet, Maxime 
    ;
    Berret, Jérémy 
    ;
    Lienhard, Reto
    ;
    Bouzelboudjen, Mahmoud 
    ;
    Arnemo, Jon M.
    ;
    Swenson, Jon E.
    ;
    Voordouw, Maarten 
    Background: Anthropogenic disturbances are changing the geographic distribution of ticks and tick-borne diseases. Over the last few decades, the tick Ixodes ricinus has expanded its range and abundance considerably in northern Europe. Concurrently, the incidence of tick-borne diseases, such as Lyme borreliosis and tick-borne encephalitis, has increased in the human populations of the Scandinavian countries. Methods: Wildlife populations can serve as sentinels for changes in the distribution of tick-borne diseases. We used serum samples from a long-term study on the Scandinavian brown bear, Ursus arctos, and standard immunological methods to test whether exposure to Borrelia burgdorferi sensu lato, the causative agent of Lyme borreliosis, and tick-borne encephalitis virus (TBEV) had increased over time. Bears had been sampled over a period of 18 years (1995-2012) from a southern area, where Ixodes ricinus ticks are present, and a northern area where ticks are uncommon or absent. Results: Bears had high levels of IgG antibodies against B. burgdorferi sensu lato but not TBEV. Bears at the southern area had higher values of anti-Borrelia IgG antibodies than bears at the northern area. Over the duration of the study, the value of anti-Borrelia IgG antibodies increased in the southern area but not the northern area. Anti-Borrelia IgG antibodies increased with the age of the bear but declined in the oldest age classes. Conclusions: Our study is consistent with the view that ticks and tick-borne pathogens are expanding their abundance and prevalence in Scandinavia. Long-term serological monitoring of large mammals can provide insight into how anthropogenic disturbances are changing the distribution of ticks and tick-borne diseases.
  • Publication
    Métadonnées seulement
    Genetic variation in transmission success of the Lyme borreliosis pathogen Borrelia afzelii
    (2015)
    Tonetti, Nicolas 
    ;
    Voordouw, Maarten 
    ;
    Durand, Jonas 
    ;
    Monnier, Séverine
    ;
    Gern, Lise 
    The vector-to-host and host-to-vector transmission steps are the two critical events that define the life cycle of any vector-borne pathogen. We expect negative genetic correlations between these two transmission phenotypes, if parasite genotypes specialized at invading the vector are less effective at infecting the vertebrate host and vice versa. We used the tick-borne bacterium Borrelia afzelii, a causative agent of Lyme borreliosis in Europe, to test whether genetic trade-offs exist between tick-to-host, systemic (host-to-tick), and a third mode of co-feeding (tick-to-tick) transmission. We worked with six strains of B. afzelii that were differentiated according to their ospC gene. We compared the three components of transmission among the B. afzelii strains using laboratory rodents as the vertebrate host and a laboratory colony of Ixodes ricinus as the tick vector. We used next generation matrix models to combine these transmission components into a single estimate of the reproductive number (R0) for each B. afzelii strain. We also tested whether these strain-specific estimates of R0 were correlated with the strain-specific frequencies in the field. We found significant genetic variation in the three transmission components among the B. afzelii strains. This is the first study to document genetic variation in co-feeding transmission for any tick-borne pathogen. We found no evidence of trade-offs as the three pairwise correlations of the transmission rates were all positive. The R0 values from our laboratory study explained 45% of the variation in the frequencies of the B. afzelii ospC strains in the field. Our study suggests that laboratory estimates of pathogen fitness can predict the distribution of pathogen strains in nature.