Percorrer por autor "Augusto, L."
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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.
- Sensitivity of biological samples for Borrelia burgdorferi s.l. infection status assessment in avian hostsPublication . Norte, A.C.; Augusto, L.; Araújo, M.; Núncio, M.S.; Ramos, J.; Lopes de Carvalho, I.Avian hosts can act as reservoirs for Borrelia burgdorferi sensu lato (s.l.), a bacterial complex that includes the etiologic agents of Lyme borreliosis. It is relevant to evaluate the infection status of the bird species to elucidate their importance as reservoir hosts, because not all contribute equally to the maintenance of Borrelia. There is a lack of a reliable non-invasive technique that allows us to assess the infection status of B. burgdorferi s.l. in wildlife. Thus, the main goal of this study was to evaluate the usefulness of biological samples such as blood and skin biopsies from two avian model species, Turdus merula and Erithacus rubecula, to diagnose B. burgdorferi s.l. infection and give information on their infectivity to ticks. Blood and skin tissues were collected from 16 Erithacus rubecula and 10 Turdus merula captured in Borrelia enzootic areas. These birds were taken into captivity and subjected to xenodiagnoses. DNA was extracted from blood and skin samples and from the fed xenodiagnostic larvae, and analysed for B. burgdorferi s.l. infection by real-time PCR directed to the flaB gene. Sensitivity of these approaches to evaluate host’s infection status will be compared and will help to elucidate B. burgdorferi s.l tropism in the birds’ organism.