Background Wildlife hosts may serve as reservoirs for strongyles which can be transmitted to dome... more Background Wildlife hosts may serve as reservoirs for strongyles which can be transmitted to domestic livestock. Therefore, we aimed to assess the risk for transmission of important nematode pathogens to domestic sheep in Sweden. The main aim of the study was to assess the risk for transmission of important pathogens from four wildlife hosts to domestic sheep. Methods First, fecal samples were collected from roe deer (n = 125), fallow deer (n = 106), red deer (n = 18) and mouflon (n = 13) in south central Sweden during the hunting season in 2019. Second, after fecal examination samples were cultured and the larvae were harvested, followed by DNA extractions. Third, all samples were then barcoded and processed for sequence analysis on the PacBio platform. Finally, bioinformatic sequence analysis was conducted with DADA2, while species diversity and richness as well as interactions between the different hosts were calculated and analyzed in R. Results Nematode ITS2 sequences were found in 225 of 262 (86%) samples. In total 31 taxa were identified amongst which 26 (86%) to the species level These were found in different combinations, amongst which 24 (77%) occurred in roe deer, 19 (61%) in fallow deer, 20 (65%) in red deer, and 10 (32%) in mouflon. Only five species are known to be associated with livestock (Chabertia ovina, Haemonchus contortus, Oesophagostomum venulosum, Teladorsagia circumcincta and Trichostrongylus axei). However, in the present study the relative abundance and prevalence of most of these species were low. The most striking exception was T. axei which was relatively abundant in all wildlife hosts. In addition, a wide range of wildlife specific nematodes such as Ostertagia leptospicularis and Spiculopteragia spp. were identified including the invasive nematode Spiculopteragia houdemeri which was found for the first time in red deer, fallow deer, and mouflon in Sweden. The difference in the number of shared species between mouflon and all cervids (n = 6) was less than between all three cervids (n = 8). Conclusion In contrast to our previous study with sheep, the relative abundance and prevalence of T. axei was generally much higher in wildlife than both H. contortus, and T. circumcincta which were negligible. Although the risk for cross-infections of nematodes between the studied wildlife hosts and sheep in Sweden cannot be ruled out, our findings indicate that the transmission potential appear to be relatively low for H. contortus and T. circumcincta, which are the two most pathogenic species in sheep.
Ixodes ricinus ticks are Scandinavia's main vector for tick‐borne encephalitis virus (TBEV), ... more Ixodes ricinus ticks are Scandinavia's main vector for tick‐borne encephalitis virus (TBEV), which infects many people annually. The aims of the present study were (i) to obtain information on the TBEV prevalence in host‐seeking I. ricinus collected within the Øresund‐Kattegat‐Skagerrak (ØKS) region, which lies in southern Norway, southern Sweden and Denmark; (ii) to analyse whether there are potential spatial patterns in the TBEV prevalence; and (iii) to understand the relationship between TBEV prevalence and meteorological factors in southern Scandinavia. Tick nymphs were collected in 2016, in southern Scandinavia, and screened for TBEV, using pools of 10 nymphs, with RT real‐time PCR, and positive samples were confirmed with pyrosequencing. Spatial autocorrelation and cluster analysis was performed with Global Moran's I and SatScan to test for spatial patterns and potential local clusters of the TBEV pool prevalence at each of the 50 sites. A climatic analysis was made to correlate parameters such as minimum, mean and maximum temperature, relative humidity and saturation deficit with TBEV pool prevalence. The climatic data were acquired from the nearest meteorological stations for 2015 and 2016. This study confirms the presence of TBEV in 12 out of 30 locations in Denmark, where six were from Jutland, three from Zealand and two from Bornholm and Falster counties. In total, five out of nine sites were positive from southern Sweden. TBEV prevalence of 0.7%, 0.5% and 0.5%, in nymphs, was found at three sites along the Oslofjord (two sites) and northern Skåne region (one site), indicating a potential concern for public health. We report an overall estimated TBEV prevalence of 0.1% in questing I. ricinus nymphs in southern Scandinavia with a region‐specific prevalence of 0.1% in Denmark, 0.2% in southern Sweden and 0.1% in southeastern Norway. No evidence of a spatial pattern or local clusters was found in the study region. We found a strong correlation between TBEV prevalence in ticks and relative humidity in Sweden and Norway, which might suggest that humidity has a role in maintaining TBEV prevalence in ticks. TBEV is an emerging tick‐borne pathogen in southern Scandinavia, and we recommend further studies to understand the TBEV transmission potential with changing climate in Scandinavia.
Background Wildlife hosts may serve as reservoirs for strongyles which can be transmitted to dome... more Background Wildlife hosts may serve as reservoirs for strongyles which can be transmitted to domestic livestock. Therefore, we aimed to assess the risk for transmission of important nematode pathogens to domestic sheep in Sweden. The main aim of the study was to assess the risk for transmission of important pathogens from four wildlife hosts to domestic sheep. Methods First, fecal samples were collected from roe deer (n = 125), fallow deer (n = 106), red deer (n = 18) and mouflon (n = 13) in south central Sweden during the hunting season in 2019. Second, after fecal examination samples were cultured and the larvae were harvested, followed by DNA extractions. Third, all samples were then barcoded and processed for sequence analysis on the PacBio platform. Finally, bioinformatic sequence analysis was conducted with DADA2, while species diversity and richness as well as interactions between the different hosts were calculated and analyzed in R. Results Nematode ITS2 sequences were found in 225 of 262 (86%) samples. In total 31 taxa were identified amongst which 26 (86%) to the species level These were found in different combinations, amongst which 24 (77%) occurred in roe deer, 19 (61%) in fallow deer, 20 (65%) in red deer, and 10 (32%) in mouflon. Only five species are known to be associated with livestock (Chabertia ovina, Haemonchus contortus, Oesophagostomum venulosum, Teladorsagia circumcincta and Trichostrongylus axei). However, in the present study the relative abundance and prevalence of most of these species were low. The most striking exception was T. axei which was relatively abundant in all wildlife hosts. In addition, a wide range of wildlife specific nematodes such as Ostertagia leptospicularis and Spiculopteragia spp. were identified including the invasive nematode Spiculopteragia houdemeri which was found for the first time in red deer, fallow deer, and mouflon in Sweden. The difference in the number of shared species between mouflon and all cervids (n = 6) was less than between all three cervids (n = 8). Conclusion In contrast to our previous study with sheep, the relative abundance and prevalence of T. axei was generally much higher in wildlife than both H. contortus, and T. circumcincta which were negligible. Although the risk for cross-infections of nematodes between the studied wildlife hosts and sheep in Sweden cannot be ruled out, our findings indicate that the transmission potential appear to be relatively low for H. contortus and T. circumcincta, which are the two most pathogenic species in sheep.
Ixodes ricinus ticks are Scandinavia's main vector for tick‐borne encephalitis virus (TBEV), ... more Ixodes ricinus ticks are Scandinavia's main vector for tick‐borne encephalitis virus (TBEV), which infects many people annually. The aims of the present study were (i) to obtain information on the TBEV prevalence in host‐seeking I. ricinus collected within the Øresund‐Kattegat‐Skagerrak (ØKS) region, which lies in southern Norway, southern Sweden and Denmark; (ii) to analyse whether there are potential spatial patterns in the TBEV prevalence; and (iii) to understand the relationship between TBEV prevalence and meteorological factors in southern Scandinavia. Tick nymphs were collected in 2016, in southern Scandinavia, and screened for TBEV, using pools of 10 nymphs, with RT real‐time PCR, and positive samples were confirmed with pyrosequencing. Spatial autocorrelation and cluster analysis was performed with Global Moran's I and SatScan to test for spatial patterns and potential local clusters of the TBEV pool prevalence at each of the 50 sites. A climatic analysis was made to correlate parameters such as minimum, mean and maximum temperature, relative humidity and saturation deficit with TBEV pool prevalence. The climatic data were acquired from the nearest meteorological stations for 2015 and 2016. This study confirms the presence of TBEV in 12 out of 30 locations in Denmark, where six were from Jutland, three from Zealand and two from Bornholm and Falster counties. In total, five out of nine sites were positive from southern Sweden. TBEV prevalence of 0.7%, 0.5% and 0.5%, in nymphs, was found at three sites along the Oslofjord (two sites) and northern Skåne region (one site), indicating a potential concern for public health. We report an overall estimated TBEV prevalence of 0.1% in questing I. ricinus nymphs in southern Scandinavia with a region‐specific prevalence of 0.1% in Denmark, 0.2% in southern Sweden and 0.1% in southeastern Norway. No evidence of a spatial pattern or local clusters was found in the study region. We found a strong correlation between TBEV prevalence in ticks and relative humidity in Sweden and Norway, which might suggest that humidity has a role in maintaining TBEV prevalence in ticks. TBEV is an emerging tick‐borne pathogen in southern Scandinavia, and we recommend further studies to understand the TBEV transmission potential with changing climate in Scandinavia.
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