Alterations in the health of hibernating bats under pathogen pressure

Abstract

In underground hibernacula temperate northern hemisphere bats are exposed to Pseudogymnoascus destructans, the fungal agent of white-nose syndrome. While pathological and epidemiological data suggest that Palearctic bats tolerate this infection, we lack knowledge about bat health under pathogen pressure. Here we report blood profiles, along with body mass index (BMI), infection intensity and hibernation temperature, in greater mouse-eared bats (Myotis myotis). We sampled three European hibernacula that differ in geomorphology and microclimatic conditions. Skin lesion counts differed between contralateral wings of a bat, suggesting variable exposure to the fungus. Analysis of blood parameters suggests a threshold of ca. 300 skin lesions on both wings, combined with poor hibernation conditions, may distinguish healthy bats from those with homeostatic disruption. Physiological effects manifested as mild metabolic acidosis, decreased glucose and peripheral blood eosinophilia which were strongly locality-dependent. Hibernating bats displaying blood homeostasis disruption had 2 °C lower body surface temperatures. A shallow BMI loss slope with increasing pathogen load suggested a high degree of infection tolerance. European greater mouse-eared bats generally survive P. destructans invasion, despite some health deterioration at higher infection intensities (dependant on hibernation conditions). Conservation measures should minimise additional stressors to conserve constrained body reserves of bats during hibernation.

Hibernation temperature-dependentPseudogymnoascus destructansinfection intensity in Palearctic bats

“…Detrimental effects of WNS vary geographically and between hosts [5,[14][15][16][17][18] as a result of alterations of disease factors that interact in enhancing or reducing mechanisms of resistance and/or tolerance to infection. While competence to control infections during torpor via immune functions is reduced [19,20], bat species may tolerate both intracellular [21] and extracellular infections [17,22].…”

Transcriptional host–pathogen responses of Pseudogymnoascus destructans and three species of bats with white-nose syndrome

“…Further research should investigate what characteristics of this species' wings might inhibit saprophytic growth by P. destructans [i.e. 70], and how these characteristics might interact with other factors, including immunogenetic variation among individual hosts, microhabitat selection by hosts during hibernation, or variation in pathogenicity among Palearctic strains of P. destructans [17,32,71,72].…”

Measurement of phagocyte activity in heterotherms

“…To collect blood from the uropatagial vessel, the bats were manually restrained and the overlying skin was disinfected with alcohol. Blood (approximately 120 μl) was then drawn from a sterile needle puncture site using a heparinised pipette tip (Pikula et al 2017;Bandouchova et al 2018). Blood was collected from the saphenous vein of 14 adult BALB/c laboratory mice (purchased from a commercial supplier) without anaesthesia (Parasuraman et al 2010).…”