Percorrer por autor "Heylen, D."
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- Borrelia wingmen: dispersal and maintenance of Borrelia burgdorferi s.l. by birdsPublication . Norte, A. C.; Ramos, J.A.; Araújo, P.M.; da Silva, L.P.; Heylen, D.; Costantini, D.; Eens, M.; Núncio, M.S.; Lopes de Carvalho, I.Lyme borreliosis, caused by Borrelia burgdorferi s.l., is the most prevalent vector-borne disease of moderate climates of the northern hemisfere. In Portugal, several Borrelia genospecies are present in questing ticks, which have different associations with vertebrate reservoir hosts and Lyme borreliosis etiology. To better understand disease risk it is necessary to evaluate the relationships among Borrelia genospecies, their tick vectors and vertebrate reservoir hosts.
- Bridging of cryptic Borrelia cycles in European songbirdsPublication . Heylen, D.; Krawczyk, A.; Lopes de Carvalho, I.; N uncio, M.S.; Sprong, H.; Norte, A.C.The principal European vector for Borrelia burgdorferi s.l., the causative agents of Lyme disease, is the host-generalist tick Ixodes ricinus. Almost all terrestrial host-specialist ticks have been supposed not to contribute to the terrestrial Borrelia transmission cycles. Through an experiment with blackbirds, we show successful transmission by the widespread I. frontalis, an abundant bird-specialized tick that infests a broad range of songbirds. In the first phase of the experiment, we obtained Borrelia-infected I. frontalis (infection rate: 19%) and I. ricinus (17%) nymphs by exposing larvae to wild blackbirds that carried several genospecies (Borrelia turdi, B. valaisiana, B. burgdorferi s.s.). In the second phase, pathogen-free blackbirds were exposed to these infected nymphs. Both tick species were able to infect the birds, as indicated by the analysis of xenodiagnostic I. ricinus larvae which provided evidence for both co-feeding and systemic transmission (infection rates: 10%-60%). Ixodes frontalis was shown to transmit B. turdi spirochetes, while I. ricinus transmitted both B. turdi and B. valaisiana. Neither species transmitted B. burgdorferi s.s. European enzootic cycles of Borrelia between songbirds and their ornithophilic ticks do exist, with I. ricinus potentially acting as a bridging vector towards mammals, including man.
- A comparative test of ixodid tick identification by a network of European researchersPublication . Estrada-Peña, A.; D'Amico, G.; Palomar, A.M.; Dupraz, M.; Fonville, M.; Heylen, D.; Habela, M.A.; Hornok, S.; Lempereur, L.; Madder, M.; Núncio, M.S.; Otranto, D.; Pfaffle, M.; Plantard, O.; Santos-Silva, M.M.; Sprong, H.; Vatansever, Z.; Vial, L.; Mihalca, A.D.This study reports the results of a comparative test of identification of ticks occurring in Western Europe and Northern Africa. A total of 14 laboratories were voluntarily enrolled in the test. Each participant received between 22 and 25 specimens of adult and nymphal ticks of 11 species: Dermacentor marginatus, D. reticulatus, Haemaphysalis punctata, Hyalomma lusitanicum, Hy. marginatum, Ixodes ricinus, I. hexagonus, Rhipicephalus annulatus, R. bursa, R. rossicus, and/or R. sanguineus s.l. Ticks were morphologically identified by three of the co-authors and the identification confirmed by a fourth co-author who used molecular methods based on several genes. Then ticks were randomly selected and blindly distributed among participants, together with a questionnaire. Only specimens collected while questing and, if possible, in the same survey, were circulated. Because of the random nature of the test, a participant could receive several specimens of the same species. Species in the different genera had variable misidentification rates (MR) of 7% (Dermacentor), 14% (Ixodes), 19% (Haemaphysalis), 36% (Hyalomma), and 54% (Rhipicephalus). Within genera, the MR was also variable ranging from 5.4% for I. ricinus or 7.4% for D. marginatus or D. reticulatus to 100% for R. rossicus. The test provided a total misidentification rate of 29.6% of the species of ticks. There are no significant differences in MR according to the sex of the tick. Participants were requested to perform a second round of identifications on the same set of ticks, using only purposely prepared keys (without illustrations), circulated to the enrolled participants, including 2 species of the genus Dermacentor, 8 of Haemaphysalis, 10 of Hyalomma, 23 of Ixodes, and 6 of Rhipicephalus. The average MR in the second round was 28%: 0% (Dermacentor), 33% (Haemaphysalis), 30% (Hyalomma) 18% (Ixodes), and 50% (Rhipicephalus). Species which are not reported in the countries of a participating laboratory had always highest MR, i.e. purely Mediterranean species had highest MR by laboratories in Central and Northern Europe. Participants expressed their concerns about a correct identification for almost 50% of the ticks of the genera Hyalomma and Rhipicephalus. The results revealed less than total confidence in identifying the most prominent species of ticks in the Western Palearctic, and underpin the need for reference libraries for specialists involved in this task. Results also showed that a combination of certain genes may adequately identify the target species of ticks.
- Host-parasite interactions between Borrelia burgdorferi s.l. and its avian reservoir hostsPublication . Norte, A.C.; Heylen, D.; Margos, G.; Fingerle, V.; Becker, N.; Araújo, P.M.; da Silva, L.P.; Sprong, H.; Krawczyk, A.; Costantini, D.; Eens, M.; Núncio, M.S.; Ramos, J.A.; Lopes de Carvalho, I.Borrelia burgdorferi sensu lato (s.l.) is maintained in enzootic cycles in nature by vertebrate reservoir hosts, including mammals, lizards and birds. To understand the eco-epidemiology of Lyme borreliosis it is necessary to evaluate the relationships among Borrelia genospecies, their tick vectors and vertebrate reservoir hosts. We surveyed infection prevalence in avian hosts and using wild birds as models, we performed transmission experiments, assessed the physiological impact of infection in reservoir hosts and how exposure to stress could affect the host’s infectivity to vector ticks. Additionally, we evaluated the population structure of an avian-associated Borrelia genospecies.
- Pandora's flying box - Borrelia burgdorferi sensu lato prevalence in Ixodes species from birds throughout EuropePublication . Norte, A. C.; Ramos, J.A.; Núncio, M.S.; Margos, G.; Fingerle, V.; Adamik, P.; Alivizatos, H.; Barba, E.; Barrientos, R.; Cauchard, L.; Csörgo, T.; Diakou, A.; Dingemanse, N.J.; Doligez, B.; Dubiec, A.; Eeva, T.; Flaisz, B.; Grim, T.; Hau, M.; Heylen, D.; Hornok, S.; Kazantzidis, S.; Kováts, D.; Krause, F.; Literak, I.; Mänd, R.; Mentesana, L.; Morinay, J.; Mutanen, M.; Neto, J.; Nováková, M.; Sanz, J.J.; Silva, L.P.; Sprong, H.; Tirri, I.S.; Török, J.; Trilar, T.; Tyller, Z.; Visser, M.E.; Lopes de Carvalho, I.Birds are important hosts for ticks and may act as reservoirs for several zoonotic pathogens. Because of their high mobility, especially of the long distance migratory species, they can act as dispersers for ticks and pathogens, ultimately affecting their distribution and phylogeography.
- The importance of wildlife health on zoonotic bacteria transmission: interactions between Borrelia burgdorferi s.l. and its avian hostsPublication . Norte, A.C.; Heylen, D.; Araújo, P.M.; Pascoal da Silva, L.; Sprong, H.; Krawczyk, A.; Costantini, D.; Eens, M.; Núncio, M.S.; Ramos, J.A.; Lopes de Carvalho, I.Borrelia burgdorferi sensu lato (s.l.) is a tick-borne zoonotic agent maintained in enzootic cycles in nature by vertebrate reservoir hosts, including mammals, lizards and birds. To understand the eco-epidemiology of Lyme borreliosis it is necessary to evaluate the relationships between Borrelia genospecies and vertebrate reservoir hosts. We surveyed Borrelia infection prevalence in avian hosts and using wild birds as models, we assessed the physiological impact of infection in reservoir hosts and how exposure to stress could affect hosts’ infectivity to vector ticks. This helps to understand how these host-parasite interactions may affect tick-borne zoonotic agents’ circulation and transmission, and, ultimately, disease risk. Thrushes (Turdus spp.) were the most important birds in the enzootic cycle of Borrelia. The diversity of Borrelia genospecies detected in ticks feeding on birds was high, and the most common genospecies was B. garinii, a pathogenic genospecies. The ubiquitous blackbird Turdus merula successfully transmitted B. turdi, B. valaisiana and B. burgdorferi s.s. to vector ticks in laboratory conditions. There was no evidence that exposure to stress increased infectivity of wild avian hosts to vector ticks in an experiment performed in captivity. However, oxidative balance (protein carbonyls and glutathione peroxidase levels) of naïve blackbirds was affected by experimental infection with Borrelia, suggesting that these bacteria may inflict non-negligible physiological harm on its natural reservoir hosts with potential impact on transmission success.
- Tissue infection by Borrelia burgdorferi s.l. in natural and experimental infected avian hostsPublication . Norte, A.C.; Carvalho, I.L.; Núncio, M.S.; Araújo, P.M.; Matthysen, E.; Ramos, J.A.; Heylen, D.Borrelia burgdorferi sl.l. is a bacterial complex that includes pathognic and non-pathogenic genospecies to humans, with diferente reservoir host and vector species associations patterns. The study of the tropismo of B. Burgdorferi sl.l. in the hosts, how the infection is sequestered in diferente organs, and whether i tis maintained in circulation and/or in the host´s skin, is importante to understand pathogenicity and reservoir competency.