Tick-borne diseases in roe deer - seroprevalence, possible cut-off and effects on health

Abstract: Understanding the interaction between roe deer and pathogens could potentially help us improve the health in both roe deer and humans. Here, I focused on broadening our basic understanding about three specific tick-borne pathogens, Anaplasma phagocytophilum, Borrelia burgdorferi s.l. and Tick-borne encephalitis virus (TBEV), and their relationship with roe deer (Capreolus capreolus). In this study, for all three pathogens, I aimed to determine roe deer´s capability to function as an indicator species, to establish a seroprevalence, identify factors affecting the seroprevalence in roe deer and, lastly, examine if these pathogens have a negative effect of roe deer’s health. Serological data for above mentioned pathogens, haematological parameters and body weight were collected from 51 adult and 49 neonate fawns. Additionally, for neonate fawns also number of ticks, lifespan, and body temperature were examined. Multiple statistical analyses were performed. The sero-prevalence in Sweden was determined to be 82%, 43% and 53% respectively for A. phagocyto-philum, B. burgdorferi s.l and TBEV. Antibodies were found for all pathogens in both age groups indicating roe deer as a functional sentinel species for all pathogens in this study. A statistical difference between areas regarding the seroprevalence for A. phagocytophilum and TBEV were found with a higher mean in Bogesund. This is discussed in relation to difference in the abundance of roe deer and size of tick population. A correlation between serological data of B. burgdorferi s.l and sex were found with findings pointing towards internal factors. Multiple correlations were found between serological data and health parameters. Continued research around these results is needed to make further inference about cause and effect.