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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 ticks

Publication . 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.

2022-01Journal article

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Detection of pathogenic microorganisms in ticks collected from wild boars (Sus scrofa) in a recreational park in Portugal

Publication . Guerreiro-Nunes, Andreia; Sousa, Rita de; Núncio, Maria Sofia; Norte, Ana Cláudia; Lopes de Carvalho, Isabel

[Extract] The Tapada Nacional de Mafra is a Portuguese hunting ground located in the Lisbon district, regularly visited by the public for tourism, environmental education and hunting activities. Its forest consists of an enormous plant diversity with almost 100 plants identified, and with the maritime pine (Pinus pinaster), the stone pine (Pinus pinea), and the cork oak (Quercus suber) being especially abundant (Norte et al. 2012). Furthermore, mammal species such as the wild boar (Sus scrofa, are frequently sighted in close proximity to human trails. These animals are important reproduction hosts for ticks and may play a role in the transmission of tick-borne pathogens. Ticks are vectors of several infectious agents, and consequently, their parasitic relationship with humans can cause various diseases of public health importance. The identification of those pathogens in circulation in different geographic areas contributes to a better understanding of the epidemiology of tick-related diseases, such as Lyme borreliosis, relapsing fever (RF), rickettsioses and tularemia. [...]

2024-11-14Journal article

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