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

• Published in: Microbial ecology Vol. 83; no. 1; pp. 202 - 215
• Main Authors: 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.
• Format: Journal Article
• Language: English
• Published: New York Springer US 2022; Springer Nature B.V
• Subjects: Animals; Anthropogenic factors; Biomedical and Life Sciences; Biopsy; Blood; Borrelia; Borrelia burgdorferi; Borrelia burgdorferi Group - physiology; Captivity; Disease resistance; Ecology; Environmental changes; Environmental stress; Exposure; Geoecology/Natural Processes; Host Microbe Interactions; Hosts; Human influences; Immunosuppression; Infections; Infectivity; Ixodes - microbiology; Leukocytes (neutrophilic); Life Sciences; Lyme Disease - microbiology; Lyme Disease - veterinary; Microbial Ecology; Microbiology; Nature Conservation; Physiology; Skin; Songbirds - microbiology; Stress (physiology); Ticks; Transmission efficiency; Water Quality/Water Pollution; Xenodiagnosis; Reservoir host; Birds; Immunosuppression; Xenodiagnosis; Stress; Borrelia
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-021-01738-3

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.