As habitats become increasingly urbanized, wildlife are exposed to artificial light at night (ALAN). Greater exposure to ALAN can have detrimental effects on animal physiology, such as suppressing components of the host immune system. However, how these changes ultimately affect infectious disease dynamics remains poorly understood.
Meredith Kernbach, a PhD candidate at the University of South Florida, is working to address how ALAN affects infectious disease. Meredith and collaborators have worked extensively on the effects of ALAN in house sparrows (Passer domesticus), a widely distributed songbird in urban habitats that also serves as one of the primary reservoir hosts for West Nile virus (WNV). In recent work published in Proceedings of the Royal Society B, Meredith and collaborators experimentally demonstrated that ALAN extends the infectious-to-vector window of house sparrows by two days but has no overall effect on host mortality. A simple computational model of WNV dynamics suggested that this extension to the house sparrow infectious period could increase the epidemic potential of this mosquito-borne disease by up to approximately 41%.
In ongoing work, Meredith and collaborators repeated their original house sparrow experiment to assess how the spectral composition of ALAN might exacerbate or dampen these previously observed effects. Their new experiment exposed birds infected with WNV to a broad-spectrum ALAN, natural light control, and more environmentally friendly amber-hue ALAN. Birds exposed to the broad-spectrum ALAN has elevated mortality to WNV, whereas birds exposed to the amber-hue ALAN had lower viremia and similar disease-induced mortality to the control birds.
This work suggests that the spectral composition of ALAN is important to consider in future studies of urbanization, animal physiology, and infectious disease. This work also may help prioritize nighttime lighting methods to reduce parasite risks and potential harm to wildlife.
Follow Meredith on Twitter (@MeKernbach) for updates about this ongoing set of studies.
- SICB 2020: Artificial Light at Night and West Nile Virus in House Sparrows - January 15, 2020