Browsing by Author "Krawczyk, A."
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- 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.
- 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.
- 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.