Seasonal Pattern of Prevalence and Excretion of Eggs of Baylisascaris transfuga in the Brown Bear (Ursus arctos).

Ladislav Molnár,Alžbeta Königová,Zuzana Vasilková,Martina Tomková,Marián Várady,Peter Major

doi:10.3390/ani10122428

Abstract

Simple SummaryThe main goal of this study was to monitor the seasonal dynamics of faecal egg counts (FEC) expressed as eggs per gram (EPG) and intensity of excretion of the egg nematode Baylisascaris transfuga in the European brown bear over three years. The number of nematode eggs in the faecal samples began to rise in the spring and peaked in the autumn throughout the study period. Presence of nematode eggs in the samples was also observed in the winter season. Of the environmental factors, the seasonal dynamics and intensity of the infection were most influenced by temperature, while humidity and mean precipitation did not affect it. Increasing mean temperatures during the winter and short or no hibernation together with the presence of B. transfuga infection may negatively affect the health of infected bears. Due to the zoonotic potential of the parasite and the increased occurrence of bears in the vicinity of human dwellings, the dissemination of propagative stages may also pose a threat to human health.The seasonal dynamics of the prevalence, abundance, and mean intensity of egg excretion by the nematode parasite Baylisascaris transfuga in the European brown bear (Ursus arctos) were monitored relative to environmental factors (mean temperature, humidity, and temperature) over three years. The prevalence, abundance, and mean intensity of egg excretion tended to increase from spring to autumn throughout the monitoring period. The seasonal prevalence (84.2–90.6%), abundance (470.2–545.3 eggs per gramme (EPG) of faeces), mean intensity of excretion (558.3–602.1 EPG), and number of eggs (1150 EPG) were highest in autumn. The prevalence of eggs (up to 48.5%), abundance (37.8–60.6 EPG), and mean intensity of excretion (94.4–125.0 EPG) were high in winter, despite the period of hibernation. The seasonal dynamics of B. transfuga abundance in bears, the mean temperature between spring and autumn, and the seasonal trend of increase in intensity of egg excretion with temperature from winter to summer were interrelated. Abundance differed significantly between winter and autumn, spring and autumn, and summer and autumn (p < 0.0001) in all years and between spring and summer in 2016 (p < 0.005), 2017 (p < 0.05). B. transfuga abundance differed significantly between the seasons over the three years only in spring (p ≤ 0.0001).

Highlights

The European brown bear (Ursus arctos) is present in 22 European countries, with an estimated total number of approximately 17,000 individuals [1]
Our study describes seasonal patterns of mean excretion, abundance, and prevalence of B. transfuga eggs by brown bears in a Central Europe area
Limited data has been reported for the seasonal dynamics of B. transfuga prevalence in populations of free-ranging bears, with some conflicting results

Summary

Introduction

The European brown bear (Ursus arctos) is present in 22 European countries, with an estimated total number of approximately 17,000 individuals [1]. Most of these populations are strictly protected and are currently increasing [2]. The Carpathian population includes brown bears in Slovakia, Poland, the Ukraine, and Romania. The population in the Carpathian Mountains is estimated at about. More than 90% of bears in Slovakia belong to the. East Carpathian subpopulation in north-eastern Slovakia, south-eastern Poland, and the Ukrainian. Some of these bears likely have transborder home ranges [3].

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