Browsing by Author "Ramos, J. A."
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- Effects of stress exposure in captivity on physiology and infection in avian hosts: no evidence of increased Borrelia burgdorferi s.l. infectivity to vector ticksPublication . Norte, A. C.; Araújo, P. M.; Augusto, L.; Guímaro, H.; Santos, S.; Lopes, R. J.; Núncio, M. S.; Ramos, J. A.; Lopes de Carvalho, I.Exposure to environmental stressors, an increasingly recurring event in natural communities due to anthropogenic-induced environmental change, profoundly impacts disease emergence and spread. One mechanism through which this occurs is through stress-induced immunosuppression increasing disease susceptibility, prevalence, intensity and reactivation in hosts. We experimentally evaluated how exposure to stressors affected both the physiology of avian hosts and the prevalence of the zoonotic bacteria Borrelia burgdorferi sensu lato (s.l.), in two model species-the blackbird Turdus merula and the robin Erithacus rubecula captured in the wild, using xenodiagnoses and analysis of skin biopsies and blood. Although exposure to stressors in captivity induced physiological stress in birds (increased the number of circulating heterophils), there was no evidence of increased infectivity to xenodiagnostic ticks. However, Borrelia detection in the blood for both experimental groups of blackbirds was higher by the end of the captivity period. The infectivity and efficiency of transmission were higher for blackbirds than robins. When comparing different methodologies to determine infection status, xenodiagnosis was a more sensitive method than skin biopsies and blood samples, which could be attributed to mild levels of infection in these avian hosts and/or dynamics and timing of Borrelia infection relapses and redistribution in tissues.
- The importance of lizards and small mammals as reservoirs for Borrelia lusitaniae in PortugalPublication . Norte, A.C.; Alves da Silva, A.; Alves, J.; da Silva, L. P.; Núncio, M. S.; Escudero, R.; Anda, P.; Ramos, J. A.; Lopes de Carvalho, I.Borrelia lusitaniae is a pathogen frequent in the Mediterranean area. Apart from lizards, evidence for birds and small mammals as competent reservoirs for this genospecies has been occasional. We collected questing ticks, skin biopsies and Ixodes sp. ticks feeding on lizards, birds and small mammals in a B. burgdorferi s.l. (sensu lato) enzootic area to assess their importance in the maintenance of B. lusitaniae. Borrelia lusitaniae was the most prevalent genospecies in questing ticks and was commonly found in larvae feeding on Psammodromus algirus. One biopsy infected with B. lusitaniae was collected from the tail of one Podarcis hispanica, which suggests systemic infection. Ixodes ricinus larvae feeding on Apodemus sylvaticus were infected with B. lusitaniae but with a lower prevalence. Our results reinforce the importance of lizards as reservoirs for B. lusitaniae, suggesting that P. algirus, in particular, acts as main reservoir for B. lusitaniae in Portugal.