Coexistence of Pathogens in Host-Seeking and Feeding Ticks within a Single Natural Habitat in Central Germany

The importance of established and emerging tick-borne pathogens in Central and Northern Europe is steadily increasing. In 2007, we collected Ixodes ricinus ticks feeding on birds (n = 211) and rodents (n = 273), as well as host-seeking stages (n = 196), in a habitat in central Germany. In order to find out more about their natural transmission cycles, the ticks were tested for the presence of Lyme disease borreliae, Anaplasma phagocytophilum, spotted fever group (SFG) rickettsiae, Francisella tularensis, and babesiae. Altogether, 20.1% of the 680 ticks examined carried at least one pathogen. Bird-feeding ticks were more frequently infected with Borrelia spp. (15.2%) and A. phagocytophilum (3.2%) than rodent-feeding ticks (2.6%; 1.1%) or questing ticks (5.1%; 0%). Babesia spp. showed higher prevalence rates in ticks parasitizing birds (13.2%) and host-seeking ticks (10.7%), whereas ticks from small mammals were less frequently infected (6.6%). SFG rickettsiae and F. tularensis were also found in ticks collected off birds (2.1%; 1.2%), rodents (1.8%; 1.5%), and vegetation (4.1%; 1.6%). Various combinations of coinfections occurred in 10.9% of all positive ticks, indicating interaction of transmission cycles. Our results suggest that birds not only are important reservoirs for several pathogens but also act as vehicles for infected ticks and might therefore play a key role in the dispersal of tick-borne diseases.Lyme borreliosis is the most frequent arthropod-borne disease in the northern hemisphere (6), but other pathogens, such as intracellular bacteria of the order Rickettsiales (Anaplasma phagocytophilum, spotted fever group [SFG] rickettsiae), Francisella tularensis, and intraerythrocytic parasites of the genus Babesia, have gained more and more importance as tick-borne agents in Europe (52). The castor bean tick (Ixodes ricinus) has a three-host life cycle, which means that it ingests a blood meal in each life stage before it molts. When transovarial transmission of a pathogen is absent or very rare, as is the case with Borrelia spp. (63), A. phagocytophilum (10), and Babesia microti (15), detection of these agents in feeding larvae is an indication of pathogen transmission from an infected reservoir host to the tick. With the exception of SFG rickettsiae, which use ticks as the vector and reservoir, established and emerging pathogens are maintained by vertebrate reservoirs during their life cycles. Although methods for detection and characterization are constantly improving, the ecology of tick-borne pathogens, particularly their reservoir host specificity, is still not understood in detail.The agents of Lyme disease form a very heterogeneous complex, which can be subdivided into several clusters by phylogenetic analysis of genes (e.g., ospA) or noncoding regions. Several bird, rodent, and reptile species act as reservoirs for these spirochetes (32).Anaplasma phagocytophilum is the causative agent of human granulocytic anaplasmosis (HGA), an influenza-like illness of humans and domestic animals which is widespread in Europe. Sheep, deer, and rodents have been discussed as reservoir hosts for HGA agents (28, 31). Birds might be of importance in the dispersal of Anaplasma-infected ticks over long distances (18).At least half of the about 30 SFG rickettsiae distributed worldwide that have been described so far are known to be pathogenic for humans. Because efficient transovarial transmission of SFG rickettsiae from female ticks to larvae has been described for several species, e.g., Rickettsia parkeri, R. slovaca, and R. helvetica, the tick vector can also be regarded as a reservoir host (38). Some small mammals, like meadow voles and chipmunks, develop a strong rickettsemia which might allow transmission to parasitizing ticks (38). Although a vehicle function of birds is hypothesized (13), further investigations are needed to ascertain their possible role as reservoir hosts for SFG rickettsiae.Tularemia is a zoonotic disease caused by F. tularensis. In Germany, only the subspecies F. tularensis subsp. holarctica is prevalent, primarily in wild mammals (lagomorphs and rodents), but humans can become infected through the bite of hematophagous arthropods, by direct contact with infected animals (mostly hares), by ingestion of contaminated food or water, or by inhalation of infected aerosols (57). Potential vectors include ticks, mosquitos, and deer flies (40). However, in Germany, only ticks seem to play a relevant role. Movements of birds that excrete the bacteria with their feces might explain the transfer to islands and over long distances (35).Besides bacterial and viral agents, pathogenic parasites are also transmitted by I. ricinus. Protozoa of the genus Babesia invade erythrocytes and cause an often life-threatening malaria-like disease in humans and animals. Rodents are frequently infected with Ba. microti, but there is still no final evidence for a reservoir role of small mammals for pathogenic Babesia species. The main reservoirs of Babesia divergens are cattle and deer (15). Recently, we discovered that bird-feeding subadult ticks are frequently infected with Ba. divergens- and Ba. microti-like species, indicating an important role of migratory passerines as reservoirs and in the dispersal of Babesia spp. (18).The aim of the present study was to gain information about the cocirculation of five tick-borne pathogens in a single natural focus, especially regarding their preferred reservoir hosts and vehicles.     

Identification of Parasitic Communities within European Ticks Using Next-Generation Sequencing

Background

Risk assessment of tick-borne and zoonotic disease emergence necessitates sound knowledge of the particular microorganisms circulating within the communities of these major vectors. Assessment of pathogens carried by wild ticks must be performed without a priori, to allow for the detection of new or unexpected agents.

Methodology/Principal Findings

We evaluated the potential of Next-Generation Sequencing techniques (NGS) to produce an inventory of parasites carried by questing ticks. Sequences corresponding to parasites from two distinct genera were recovered in Ixodes ricinus ticks collected in Eastern France: Babesia spp. and Theileria spp. Four Babesia species were identified, three of which were zoonotic: B. divergens, Babesia sp. EU1 and B. microti; and one which infects cattle, B. major. This is the first time that these last two species have been identified in France. This approach also identified new sequences corresponding to as-yet unknown organisms similar to tropical Theileria species.

Conclusions/Significance

Our findings demonstrate the capability of NGS to produce an inventory of live tick-borne parasites, which could potentially be transmitted by the ticks, and uncovers unexpected parasites in Western Europe.     

Prevalence of Tick-Borne Pathogens in Ixodes ricinus and Dermacentor reticulatus Ticks from Different Geographical Locations in Belarus

Worldwide, ticks are important vectors of human and animal pathogens. Besides Lyme Borreliosis, a variety of other bacterial and protozoal tick-borne infections are of medical interest in Europe. In this study, 553 questing and feeding Ixodes ricinus (n = 327) and Dermacentor reticulatus ticks (n = 226) were analysed by PCR for Borrelia, Rickettsia, Anaplasma, Coxiella, Francisella and Babesia species. Overall, the pathogen prevalence in ticks was 30.6% for I. ricinus and 45.6% for D. reticulatus. The majority of infections were caused by members of the spotted-fever group rickettsiae (24.4%), 9.4% of ticks were positive for Borrelia burgdorferi sensu lato, with Borrelia afzelii being the most frequently detected species (40.4%). Pathogens with low prevalence rates in ticks were Anaplasma phagocytophilum (2.2%), Coxiella burnetii (0.9%), Francisella tularensis subspecies (0.7%), Bartonella henselae (0.7%), Babesia microti (0.5%) and Babesia venatorum (0.4%). On a regional level, hotspots of pathogens were identified for A. phagocytophilum (12.5–17.2%), F. tularensis ssp. (5.5%) and C. burnetii (9.1%), suggesting established zoonotic cycles of these pathogens at least at these sites. Our survey revealed a high burden of tick-borne pathogens in questing and feeding I. ricinus and D. reticulatus ticks collected in different regions in Belarus, indicating a potential risk for humans and animals. Identified hotspots of infected ticks should be included in future surveillance studies, especially when F. tularensis ssp. and C. burnetii are involved.     

Prevalence of <Emphasis Type="Italic">Borrelia burgdorferi</Emphasis> sensu lato and <Emphasis Type="Italic">Anaplasma phagocytophilum</Emphasis> in questing <Emphasis Type="Italic">Ixodes ricinus</Emphasis> ticks in relation to the density of wild cervids

Background

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum have been considered as pathogens in animals and humans. The role of wild cervids in the epidemiology is not clear. We analyzed questing Ixodes ricinus ticks collected in spring for these pathogens from sites with high (Fjelløyvær and Strøm) and low density (Tjore, Hinnebu and Jomfruland) of wild cervids to study the spread of the pathogens in questing ticks.

Methods

For detection of Anaplasma phagocytophilum a 77-bp fragment in the msp 2 gene was used. Detection of Borrelia burgdorferi sensu lato was performed using the FL6 and FL7 primers according to sequences of conserved regions of the fla gene. The Osp A gene located on the linear 49-kb plasmid was used as target in multiplex PCR for genotyping. Genospecies-specific primers were used in the PCR for Borrelia burgdorferi sensu stricto, B. afzelii and B. garinii.

Results

Infection rates with Borrelia spp. were significantly lower at Fjelløyvær and Strøm compared to Tjore and Hinnebu; Fjelløyvær vs. Tjore (χ² = 20.27, p < 0.0001); Fjelløyvær vs. Hinnebu (χ² = 24.04, p < 0.0001); Strøm vs. Tjore (χ² = 11.47, p = 0.0007) and Strøm vs. Hinnebu (χ² = 16.63, p < 0.0001). The Borrelia genospecies were dominated by. B. afzelii (82%) followed by B. garinii (9.7%) and B. burgdorferi sensu stricto (6.9%). B. burgdorferi s.s. was only found on the island of Jomfruland. The infection rate of Anaplasma phagocytophilum showed the following figures; Fjelløyvær vs Hinnebu (χ² = 16.27, p = 0.0001); Strøm vs. Tjore (χ² = 13.16, p = 0.0003); Strøm vs. Hinnebu (χ² = 34.71, p < 0.0001); Fjelløyvær vs. Tjore (χ² = 3.19, p = 0.0742) and Fjelløyvær vs. Støm (χ² = 5.06, p = 0.0245). Wild cervids may serve as a reservoir for A. phagocytophilum. Jomfruland, with no wild cervids but high levels of migrating birds and rodents, harboured both B. burgdorferi s.l. and A. phagocytophilum in questing I. ricinus ticks. Birds and rodents may play an important role in maintaining the pathogens on Jomfruland.

Conclusion

The high abundance of roe deer and red deer on the Norwegian islands of Fjelløyvær and Strøm may reduce the infection rate of Borrelia burgdorferi sensu lato in host seeking Ixodes ricinus, in contrast to mainland sites at Hinnebu and Tjore with moderate abundance of wild cervids. The infection rate of Anaplasma phagocytophilum showed the opposite result with a high prevalence in questing ticks in localities with a high density of wild cervids compared to localities with lower density.

     

Prevalence and distribution of Borrelia and Babesia species in ticks feeding on dogs in the U.K.

Ticks were collected during March–July 2015 from dogs by veterinarians throughout the U.K. and used to estimate current prevalences and distributions of pathogens. DNA was extracted from 4750 ticks and subjected to polymerase chain reaction and sequence analysis to identify Borrelia burgdorferi sensu lato (Spirochaetales: Spirochaetaceae) and Babesia (Piroplasmida: Babesiidae) species. Of 4737 ticks [predominantly Ixodes ricinus Linneaus (Ixodida: Ixodidae)], B. burgdorferi s.l. was detected in 94 (2.0%). Four Borrelia genospecies were identified: Borrelia garinii (41.5%); Borrelia afzelli (31.9%); Borrelia burgdorferi sensu stricto (25.5%), and Borrelia spielmanii (1.1%). One Rhipicephalus sanguineus Latreille (Ixodida: Ixodidae), collected from a dog with a history of travel outside the U.K., was positive for B. garinii. Seventy ticks (1.5%) were positive for Babesia spp. Of these, 84.3% were positive for Babesia venatorum, 10.0% for Babesia vulpes sp. nov., 2.9% for Babesia divergens/Babesia capreoli and 1.4% for Babesia microti. One isolate of Babesia canis was detected in a Dermacentor reticulatus (Ixodida: Ixodidae) tick collected from a dog that had recently travelled to France. Prevalences of B. burgdorferi s.l. and Babesia spp. did not differ significantly between different regions of the U.K. The results map the widespread distribution of B. burgdorferi s.l. and Babesia spp. in ticks in the U.K. and highlight the potential for the introduction and establishment of exotic ticks and tick‐borne pathogens.     

Tularemia in Alaska, 1938 - 2010

Background

A major challenge in sheep farming during the grazing season along the coast of south-western Norway is tick-borne fever (TBF) caused by the bacteria Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus.

Methods

A study was carried out in 2007 and 2008 to examine the prevalence of A. phagocytophilum infection and effect on weaning weight in lambs. The study included 1208 lambs from farms in Sunndal Ram Circle in Møre and Romsdal County in Mid-Norway, where ticks are frequently observed. All lambs were blood sampled and serum was analyzed by an indirect fluorescent antibody assay (IFA) to determine an antibody status (positive or negative) to A. phagocytophilum infection. Weight and weight gain and possible effect of infection were analyzed using ANOVA and the MIXED procedure in SAS.

Results

The overall prevalence of infection with A. phagocytophilum was 55%. A lower weaning weight of 3% (1.34 kg, p < 0.01) was estimated in lambs seropositive to an A. phagocytophilum infection compared to seronegative lambs at an average age of 137 days.

Conclusions

The results show that A. phagocytophilum infection has an effect on lamb weight gain. The study also support previous findings that A. phagocytophilum infection is widespread in areas where ticks are prevalent, even in flocks treated prophylactic with acaricides.     

Babesia spp. Identified by PCR in Ticks Collected from Domestic and Wild Ruminants in Southern Switzerland

Concurrent infections with vector-borne pathogens affected a cattle herd in Switzerland, and one of the pathogens was identified as Babesia bigemina, which had never been observed in this country before. Therefore, a survey of the occurrence of ruminant Babesia spp. and their tick vectors in Switzerland was conducted. A total of 2,017 ticks were collected from sheep, goats, cattle, and wild ruminants (deer, roe deer, and chamois) in southern parts of Switzerland and identified morphologically. The vast majority of the ticks (99.2%) were Ixodes ricinus, but 14 ticks from sheep and goats were identified as Dermacentor marginatus and two ticks from wild ruminants were identified as Hemaphysalis punctata. PCR analyses of 700 ticks revealed the presence of Babesia divergens (n = 6), Babesia sp. genotype EU1 (n = 14), and B. major (n = 2), whose suggested occurrence was confirmed in this study by molecular analysis, and the presence of novel Babesia sp. genotype CH1 (n = 4), which is closely related to B. odocoilei and to Babesia sp. genotype RD61 reported from North America. The identification of B. divergens and B. major in ticks collected from wild ruminants cast doubt on the postulated strict host specificity of these bovine Babesia species. Furthermore, the zoonotic Babesia sp. genotype EU1 was detected in ticks collected from domestic animals but was obtained predominantly from ticks collected from wild ruminants. More than one tick containing DNA of different Babesia spp. were collected from two red deer. Hence, the role of these game animals as reservoir hosts of Babesia spp. seems to be important but requires further investigation.     

Detection of Borrelia burgdorferi s.l., Anaplasma phagocytophilum and Babesia spp. in Dermacentor reticulatus ticks found within the city of Białystok,Poland—first data

Pathogens carried by ticks pose a threat to both human and animal health across the world. Typically associated with rural landscapes, ticks appear to adapt well to life in urban recreational areas. Although Dermacentor reticulatus is commonly found across Europe, data on the prevalence of pathogens in this tick species, in an urban environment, are very limited. PCR was used to examine 368 D. reticulatus individuals collected in the Zwierzyniecki Forest Nature Reserve in Bia?ystok, Poland. In total, 10.3% of ticks were infected, with Babesia spp. (9.2%), Anaplasma phagocytophilum (0.8%) and Borrelia burgdorferi sensu lato (0.3%). Rickettsia spp., Bartonella spp., and Coxiella burnetii were not detected. Sequence analysis for Babesia-positive samples identified 79.4% of them as Babesia canis, 8.8% as Babesia microti, 5.9% as Babesia spp., 2.9% as Babesia venatorum, and 2.9% as Babesia vogeli. Results obtained in this study indicate that D. reticulatus ticks found within the urban premises of the study area are infected with at least three pathogens and therefore are an important factor in public health risk for tick-borne diseases.

     

qPCR estimates of <Emphasis Type="Italic">Babesia bovis</Emphasis> and <Emphasis Type="Italic">Babesia bigemina</Emphasis> infection levels in beef cattle and <Emphasis Type="Italic">Rhipicephalus microplus</Emphasis> larvae

Babesia spp. are tick-transmitted intraerythrocytic apicomplexan parasites that infect wild and domestic animals. Babesia bovis and B. bigemina are endemic and responsible for enormous economic losses to the livestock industry in most of the Brazilian territory, wherein the tick Rhipicephalus microplus is the unique vector. Better understanding of epidemiology and parasite–host interactions may improve the tools for disease control and genetic management for selection of resistant animals. This study aimed to detect, quantify and measure the correlation between B. bigemina and B. bovis infection levels in bovine blood and into tick, by absolute quantification of hemoparasite DNA using qPCR. Blood bovine samples and larvae pools from 10 engorged R. microplus females were collected from each Canchim heifers (5/8 Charolais?+?3/8 zebu, n?=?36). All evaluated samples were positive for both Babesia species tested. Correlations of B. bovis and B. bigemina levels between cattle and tick host were 0.58 and 0.66, respectively. These high positive correlation coefficients indicate that parasitemia load in the bovine may be dependent on or may determine the parasitemia load in the ticks.     

Large-scale preparation of active caspase-3 in E. coli by designing its thrombin-activatable precursors

Background

Combination of CHD (chromo-helicase-DNA binding protein)-specific polymerase chain reaction (PCR) with electrophoresis (PCR/electrophoresis) is the most common avian molecular sexing technique but it is lab-intensive and gel-required. Gender determination often fails when the difference in length between the PCR products of CHD-Z and CHD-W genes is too short to be resolved.

Results

Here, we are the first to introduce a PCR-melting curve analysis (PCR/MCA) to identify the gender of birds by genomic DNA, which is gel-free, quick, and inexpensive. Spilornis cheela hoya (S. c. hoya) and Pycnonotus sinensis (P. sinensis) were used to illustrate this novel molecular sexing technique. The difference in the length of CHD genes in S. c. hoya and P. sinensis is 13-, and 52-bp, respectively. Using Griffiths' P2/P8 primers, molecular sexing failed both in PCR/electrophoresis of S. c. hoya and in PCR/MCA of S. c. hoya and P. sinensis. In contrast, we redesigned sex-specific primers to yield 185- and 112-bp PCR products for the CHD-Z and CHD-W genes of S. c. hoya, respectively, using PCR/MCA. Using this specific primer set, at least 13 samples of S. c. hoya were examined simultaneously and the Tm peaks of CHD-Z and CHD-W PCR products were distinguished.

Conclusion

In this study, we introduced a high-throughput avian molecular sexing technique and successfully applied it to two species. This new method holds a great potential for use in high throughput sexing of other avian species, as well.     

Molecular identification of tick-borne pathogens in ticks collected from dogs and small ruminants from Greece

Ticks are vectors for a variety of human and animal pathogens (bacteria, protozoa and viruses). In order to investigate the pathogens carried by ticks in Greece, a total of 179 adult ticks (114 female and 65 male) were collected from domestic animals (sheep, goats and dogs) from 14 prefectures of six regions of Greece. Among them, 40 were Dermacentor marginatus, 25 Haemaphysalis parva, 22 H. sulcata, one H. punctata, 13 Ixodes gibbosus, 77 Rhipicephalus sanguineus s.l. and one R. bursa. All ticks were tested for the presence of DNA of Anaplasma spp., Babesia spp., Coxiella burnetii, Rickettsia spp. and Theileria spp. The collected ticks were examined by PCR and reverse line blot (RLB) assay. A prevalence of 20.1% for Anaplasma spp., 15.6% for Babesia spp. (identifying B. bigemina, B. divergens, B. ovis and B. crassa), 17.9% for C. burnetii, 15.1% for Rickettsia spp., and 21.2% for Theileria spp. (identifying T. annulata, T. buffeli/orientalis, T. ovis and T. lestoquardi) was found. The results of this study demonstrate the variety of tick-borne pathogens of animal and human importance circulating in Greece, and that awareness is needed to minimize the risk of infection, especially among farmers and pet owners.     

Estimation of the number and demographics of companion dogs in the UK

Background

The grey partridge is an important game bird in Europe that has declined considerably over the last decades. The production and release of farm-bred birds can be threatened by infectious agents. The objective of this study was to describe the outbreak, pathology, and blood and tissue biochemical responses in a flock of grey partridges naturally infected with Mycoplasma gallisepticum.

Results

Morbidity and mortality rates were 100% and 60%, respectively. Necropsy revealed an accumulation of caseous exudate within the infraorbital sinuses, tracheitis, pneumonia and airsacculitis. There were significant increases in activities of lactate dehydrogenase, creatine kinase and amylase, and levels of total protein and glucose in Mycoplasma-infected birds when compared to control. Catalase showed significantly lower activity in the heart, lungs, liver and gonads of Mycoplasma-infected birds. Glutathione-S-transferase activity was elevated in the eye and the associated infraorbital sinus and kidneys, and decreased in the liver. Decreased levels of reduced glutathione were found in the heart, kidneys, liver and gonads. The activity of glutathione reductase was lower only in the lungs. Compared to healthy birds, mycoplasmosis in the grey partridge caused significant differences in the level of lipid peroxidation in lungs and plasma (p < 0.05), while the ferric reducing antioxidant power was lower in the heart and kidneys (p < 0.01). Significant correlations among responses of the antioxidant parameters were found namely in the heart, lungs, spleen, liver and plasma. There were also numerous significant inter-tissue correlations of all the studied antioxidant parameters.

Conclusions

The present study demonstrates the high susceptibility of grey partridges to natural infection by M. gallisepticum, the severity of the disease based on histopathology, and the modulation of blood chemical profiles and oxidative stress-associated parameters in the avian hosts, thus enhancing the understanding of the pathogenesis of mycoplasmosis in birds. Moreover, the reported reference values can be useful for the evaluation of the state of health in grey partridges.     

Babesia sp. BQ1 (Lintan): Molecular evidence of experimental transmission to sheep by Haemaphysalis qinghaiensis and Haemaphysalis longicornis

Ovine babesiosis is an economically important disease induced by tick transmitted haemoparasites throughout the world. In China, several ovine Babesia strains have been isolated from field-collected ticks or sheep blood during the last two decades but little is known about the vector ticks and transmission pattern. Babesia sp. BQ1 (Lintan) is a Babesia strain infective for sheep and goats, isolated from blood of sheep experimentally infested with Haemaphysalis qinghaiensis collected in field. In the present study, we explored the experimental transmission of Babesia sp. BQ1 (Lintan) to sheep by H. qinghaiensis and Haemaphysalis longicornis. Based on the evidence from nested PCR, it suggested that H. qinghaiensis and H. longicornis are the potential vector ticks of Babesia sp. BQ1 (Lintan) and that larvae, nymphs and adults of both tick species were able to transmit Babesia sp. BQ1 (Lintan) to sheep. Parasites could be detected in the blood, by specific nested PCR, for one month post-infestation.     

Greenhouse gas emissions from forestry in East Norway

Purpose

So far no calculations have been made for greenhouse gas (GHG) emissions from forestry in East Norway. This region stands for 80 % of the Norwegian timber production. The aim of this study was to assess the annual GHG emissions of Norwegian forestry in the eastern parts of the country from seed production to final felling and transport of timber to sawmill and wood processing industry (cradle-to-gate inventory), based on specific Norwegian data.

Methods

The life cycle inventory was conducted with SimaPro applying primary and secondary data from Norwegian forestry. GHG emissions of fossil-related inputs from the technosphere were calculated for the functional unit of 1 m³ timber extracted and delivered to industry gate in East Norway in 2010. The analysis includes seed and seedling production, silvicultural operations, forest road construction and upgrading, thinning, final felling, timber forwarding and timber transport on road and rail from the forest to the industry. Norwegian time studies of forestry machines and operations were used to calculate efficiency, fuel consumption and transport distances. Due to the lack of specific Norwegian data in Ecoinvent, we designed and constructed unit processes based on primary and secondary data from forestry in East Norway.

Results and discussion

GHG emissions from forestry in East Norway amounted to 17.893 kg CO₂-equivalents per m³ of timber delivered to industry gate in 2010. Road transport of timber accounted for almost half of the total GHG emissions, final felling and forwarding for nearly one third of the GHG emissions. Due to longer road transport distances, pulpwood had higher impact on the climate change category than saw timber. The construction of forest roads had the highest impact on the natural land transformation category. The net CO₂ emissions of fossil CO₂ corresponded to 2.3 % of the CO₂ sequestered by 1 m³ of growing forest trees and were compared to a calculation of biogenic CO₂ release from the forest floor as a direct consequence of harvesting.

Conclusions

Shorter forwarding and road transport distances, increased logging truck size and higher proportion of railway transport may result in lower emissions per volume of transported timber. A life cycle assessment of forestry may also consider impacts on environmental categories other than climate change. Biogenic CO₂ emissions from the soil may be up to 10 times higher than the fossil-related emissions, at least in a short-term perspective, and are highly dependent on stand rotation length.     

An experimental test to compare potential and realised specificity in ticks with different ecologies

The majority of studies on ecological specialisation rely on data reflecting realised specificity, without considering species’ potential specificity. Most species of ticks, a large family of hematophagous ectoparasites, have a narrow host range in nature, but it is unclear whether this is due to host-driven adaptations or other processes (such as off-host abiotic environment). We investigated the potential specificity of two tick species with contrasting ecology by infesting three avian host species that occur in the same off-host macrohabitat but are unequally infested by the ticks in nature (i.e. have contrasting realised specificity). The endophilic specialist tick Ixodes arboricola resides inside the hosts’ nest and has high realised host specificity, whereas the exophilic generalist tick I. ricinus encounters hosts in the field and has very low realised specificity. As hosts, we used great tits (frequently infested by both tick species), blackbirds (frequently infested by I. ricinus but never by I. arboricola) and great spotted woodpeckers (no ticks of either species have been reported). If realised specificity is constrained by host-driven adaptations there should be no differences between potential and realised specificity, whereas if realised specificity is constrained by other processes potential specificity and realised specificity should be different. We found that attachment rates and weight during feeding of I. arboricola were lower on blackbirds than on great tits, whereas there were no such differences for I. ricinus. No ticks of either species attached to woodpeckers. These results indicate that realised host specificity of ticks is, at least partially, constrained by host-driven adaptations. This specificity therefore strongly depends on the ticks’ encounter rates with particular host types, which are affected by the ticks’ off-host ecological requirements, behaviour and life-history characteristics.     

Artemisone inhibits in vitro and in vivo propagation of Babesia bovis and B. bigemina parasites

Artemisone was evaluated, in in vitro and in vivo, for control of bovine babesiosis caused by Babesia bigemina and Babesiabovis parasites. In vitro, artemisone reduced parasitemia in a dose-dependent manner: the inhibitory effects increased gradually, reaching a maximum inhibition of 99.6% and 86.4% for B. bigemina and B. bovis, respectively 72 h after initiation of treatment with initial parasitemia of 0.5%. In calves infected with either B. bigemina or B. bovis artemisone treatment was well tolerated and prevented development of acute babesiosis in all animals except for one B. bovis-infected calf. The treatment did not eliminate all blood parasites, and recovered animals carried a persistent low-level infection. Treatment with artemisone may be useful as an alternative drug for preventing the pathology that results from babesiosis, without interfering with acquired immune protection following recovery from an acute babesiosis infection or vaccination.     

Molecular Investigations of Rickettsia helvetica Infection in Dogs,Foxes, Humans,and Ixodes Ticks

Rickettsia helvetica, a tick-borne member of the spotted-fever-group rickettsiae, is a suspected pathogen in humans; however, its role in animals is unknown. The aims of this study were to establish a R. helvetica-specific real-time TaqMan PCR assay and apply it to the analysis of tick vectors (to determine potential exposure risk) and blood samples from Canidae and humans (to determine prevalence of infection). The newly designed 23S rRNA gene assay for R. helvetica was more sensitive than a published citrate synthase gene (gltA) assay for several rickettsiae. Blood samples from 884 dogs, 58 foxes, and 214 human patients and 2,073 ticks (Ixodes spp.) collected from either vegetation or animals were analyzed. Although the maximal likelihood estimate of prevalence was 12% in unfed ticks and 36% in ticks collected from animals, none of the 1,156 blood samples tested PCR positive. Ticks from cats were more frequently PCR positive than ticks from dogs. Sequencing of the 23S rRNA and/or the gltA gene of 17 tick pools confirmed the presence of R. helvetica. Additionally, Rickettsia monacensis, which has not been previously found in Switzerland, was identified. In conclusion, R. helvetica was frequently detected in the tick population but not in blood samples. Nevertheless, due to the broad host range of Ixodes ticks and the high rate of infestation with this agent (i.e., R. helvetica was 13 times more frequent in unfed ticks than the tick-borne encephalitis virus), many mammals may be exposed to R. helvetica. The PCR assay described here represents an important tool for studying this topic.Tick-borne rickettsioses are caused by intracellular bacteria belonging to the spotted fever group (SFG) of the genus Rickettsia. The latter comprises more than 20 different species, of which an increasing number are known to be associated with human and animal diseases. The SFG rickettsiae are distributed worldwide, and their distribution depends upon the occurrence of tick species. The most common tick in Europe is Ixodes ricinus, which was found to harbor Rickettsia helvetica. R. helvetica is transmitted not only transstadially but also transovarially in I. ricinus. Therefore, this tick is both a vector and a reservoir for R. helvetica. Due to the broad host range of I. ricinus, many mammalian species, including humans, can serve as hosts. Therefore, these host species may potentially be exposed to R. helvetica. R. helvetica is a suspected pathogen in humans, and the symptoms described for infections in humans include fever, headache, arthralgia, and myalgia (1, 3, 7, 21, 34). The agent also has been implicated in two cases of fatal perimyocarditis (20, 22).Interestingly, despite the wide distribution of I. ricinus ticks and the high rate of infection of these ticks with R. helvetica that has been reported in several European countries (2, 9, 18, 19, 25, 29, 35, 42), larger studies discussing the prevalence of the infection in humans and animals are scarce. No studies evaluating the importance of R. helvetica in pets or farm animals are available as yet. It is unknown whether these animals can serve as a reservoir or develop clinical signs after infection.Rickettsial infections have been reported to represent the third most common vector-borne disease acquired during international travel and are therefore considered a common cause of fever of unknown origin in returned travelers (24). As the occurrence of tick-borne infectious diseases, and particularly rickettsial infections, is increasing in humans worldwide (26), it may be assumed that the same holds true for companion animals. In dogs, fever of unknown origin that is responsive to antibiotic treatment is frequently observed. In these cases, an infectious agent is suspected but rarely, if ever, confirmed. R. helvetica infections may be the underlying cause in some of these cases, even if the patient does not have a travel history, since exposure to R. helvetica-infected I. ricinus ticks may have occurred locally.To date, the diagnosis of rickettsial infection has most often been confirmed by serological testing. However, antibodies are not detectable prior to the second week of illness for any rickettsial disease studied thus far. Moreover, except for detection of seroconversion or a fourfold increase in titer, a positive serology result does not necessarily indicate an acute infection. A standardized sensitive and specific molecular method for the confirmation of R. helvetica infections would facilitate not only its diagnosis but also prevalence studies. This in turn could increase the awareness of physicians and veterinarians who are confronted with diseased individuals.Therefore, the aims of the present study were as follows: first, to establish a sensitive real-time PCR assay specific for R. helvetica; second, to study tick vectors for R. helvetica to assess the potential exposure risk for animals and humans; and third, to evaluate blood samples from Canidae and humans to assess the occurrence of R. helvetica infections.(These studies were conducted by A. Perreten as partial fulfillment of the requirements for a doctoral thesis at the Vetsuisse Faculty, University of Zurich.)     

Forecasting next season’s <Emphasis Type="Italic">Ixodes ricinus</Emphasis> nymphal density: the example of southern Germany 2018

The castor bean tick, Ixodes ricinus (L.) (Ixodida: Ixodidae), is the principal vector of pathogens causing tick-borne encephalitis or Lyme borreliosis in Europe. It is therefore of general interest to make an estimate of the density of I. ricinus for the whole year at the beginning of the tick season. There are two necessary conditions for making a successful prediction: a long homogeneous time series of observed tick density and a clear biological relationship between environmental predictors and tick density. A 9-year time series covering the period 2009–2017 of nymphal I. ricinus flagged at monthly intervals in southern Germany has been used. With the hypothesis that I. ricinus density is triggered by the fructification of the European beech 2 years before, the mean annual temperature of the previous year, and the current mean winter temperature (December–February), a forecast of the annual nymphal tick density has been made. Therefore, a Poisson regression model was generated resulting in an explained variance of 93.4% and an error of \(\hbox {RMSE} = 21\) ticks per \(100\,\hbox {m}^2\) (annual \(\hbox {MEAN} = 260\) collected ticks/\(100\,\hbox {m}^2\)). An independent verification of the forecast for the year 2017 resulted in 187 predicted versus 180 observed nymphs per \(100\,\hbox {m}^2\). For the year 2018 a relatively high number of 443 questing I. ricinus nymphs per \(100\,\hbox {m}^2\) is forecasted, i.e., a “good” tick year.