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Invasive mammals are responsible for the majority of native species extinctions on islands. While most of these extinction events will be due to novel interactions between species (e.g. exotic predators and naive prey), it is more unusual to find incidences where a newly invasive species causes the decline/extinction of a native species on an island when they normally coexist elsewhere in their overlapping mainland ranges. We investigated if resource competition between two insectivorous small mammals was playing a significant role in the rapid replacement of the native pygmy shrew Sorex minutus in the presence of the recently invading greater white-toothed shrew Crocidura russula on the island of Ireland. We used DNA metabarcoding of gut contents from >300 individuals of both species to determine each species' diet and measured the body size (weight and length) during different stages of the invasion in Ireland (before, during and after the species come into contact with one another) and on a French island where both species have long coexisted (acting as a natural 'control' site). Dietary composition, niche width and overlap and body size were compared in these different stages. The body size of the invasive C. russula and composition of its diet changes between when it first invades an area and after it becomes established. During the initial stages of the invasion, individual shrews are larger and consume larger sized invertebrate prey species. During later stages of the invasion, C. russula switches to consuming smaller prey taxa that are more essential for the native species. As a result, the level of interspecific dietary overlap increases from between 11% and 14% when they first come into contact with each other to between 39% and 46% after the invasion. Here we show that an invasive species can quickly alter its dietary niche in a new environment, ultimately causing the replacement of a native species. In addition, the invasive shrew could also be potentially exhausting local resources of larger invertebrate species. These subsequent changes in terrestrial invertebrate communities could have severe impacts further downstream on ecosystem functioning and services., (© 2023 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.)

Background: Ticks and tick-borne pathogens (TBPs) represent a significant economic burden to cattle farming in sub-Saharan Africa including Nigeria. However, in the northern part of this country, where the largest livestock population resides, little is known about the contemporary diversity of ticks and TBPs. This area is particularly vulnerable to climate change, undergoing marked transformation of habitat and associated flora and fauna that is also likely to include ticks. This study aimed to document the occurrence of tick species and Apicomplexan TBPs in cattle from north-western Nigeria., Methods: In 2017, ticks were collected from cattle in Zamfara and Sokoto States and identified morphologically. Additionally, a subset of ticks was screened molecularly for the detection of apicomplexan DNA., Results: A total of 494 adult ticks were collected from 80 cattle in Zamfara and 65 cattle in Sokoto State. Nine tick species were encountered, among which the presence of one, Hyalomma turanicum, had not previously been recorded in Nigeria. Hyalomma rufipes was the most prevalent tick infesting cattle in Zamfara State (76%), while Hyalomma dromedarii was the most prevalent in Sokoto State (44%), confirming the widespread transfer of this species from camels onto livestock and its adaptation to cattle in the region. Of 159 ticks screened, 2 out of 54 (3.7%) from Zamfara State and 29 out of 105 (27.6%) from Sokoto State harboured DNA of Theileria annulata, the agent of tropical theileriosis., Conclusions: This study confirms the presence of a broad diversity of tick species in cattle from north-western Nigeria, providing the first locality records for Zamfara State. The occurrence of H. turanicum indicates a distribution of this tick beyond northern Africa. This study provides the first report for T. annulata in Nigerian ticks. Given its enormous burden on livestock farming in north Africa and across Asia, further investigations are needed to better understand its epidemiology, vector transmission and potential clinical significance in cattle from northern Nigeria and neighbouring Sahelian countries.

Coccidiosis caused by Eimeria species is a well-recognized disease of livestock. Enteric Eimeria infections are common, but disease usually only manifests when infection intensity is abnormally high. Campylobacter species are important zoonotic enteric bacterial pathogens for which livestock are important reservoir hosts. The diversity and epidemiology of ovine Eimeria and Campylobacter infections on two farms in north-western England were explored through a 24-month survey of shedding in sheep feces. Most animals were infected with at least one of 10 different Eimeria species, among which E. bakuensis and E. ovinoidalis were most common. An animal's age and the season of sampling were associated with the probability and intensity of Eimeria infection. Season of sampling was also associated with the probability of Campylobacter infection. Interestingly, higher intensities of Eimeria infections were significantly more common in animals not co-infected with Campylobacter. We explored the determinants of E. bakuensis and E. ovinoidalis infections, observing that being infected with either significantly increased the likelihood of infection with the other. The prevalence of E. ovinoidalis infections was significantly lower in sheep infected with Campylobacter. Recognition that co-infectors shape the dynamics of parasite infection is relevant to the design of effective infection control programmes.

Trypanosomes have long been recognised as being amongst the most important protozoan parasites of vertebrates, from both medical and veterinary perspectives. Whilst numerous insect species have been identified as vectors, the role of ticks is less well understood. Here we report the isolation and partial molecular characterisation of a novel trypanosome from questing Ixodes ricinus ticks collected in Slovakia. The trypanosome was isolated in tick cell culture and then partially characterised by microscopy and amplification of fragments of the 18S rRNA and 24Sα rDNA genes. Analysis of the resultant sequences suggests that the trypanosome designated as Trypanosoma sp. Bratislava1 may be a new species closely related to several species or strains of trypanosomes isolated from, or detected in, ticks in South America and Asia, and to Trypanosoma caninum isolated from dogs in Brazil. This study highlights the potential involvement of ixodid ticks in the epidemiology of trypanosomes, as well as the use of tick cell lines for isolation of such tick-borne protozoa. Further studies are required to investigate the epidemiology, transmission and life cycle of this putative novel species., (Copyright © 2020 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Lyme borreliosis (LB) is a tick-borne disease caused by Borrelia burgdorferi sensu lato complex. In Europe, it is predominately transmitted by the sheep tick, Ixodes ricinus. Compared with other European countries, the United Kingdom (UK) is considered to have a low incidence of LB, although this varies regionally. To determine whether an association exists between tick bite consultations and LB incidence in the UK, retrospective questionnaires were sent to general practitioners (GPs) in high (Wiltshire), medium (Cumbria) and low (Wales) incidence areas. During 2011, the greatest incidence of consultations for tick bites was reported by GPs in Cumbria (204 consultations per 100,000 inhabitants), followed by Wiltshire (160 per 100,000 population) and Wales (54 per 100,000 population). In Wiltshire and Cumbria, GPs predominantly provided advice on tick removal, whilst Welsh GPs mostly advised patients on tick bite prevention. Focusing on Cumbria during 2011-2013, 72.5% of GPs removed ticks from patients (incidence of 101 consultations per 100,000 population), and more GPs diagnosed LB based on clinical features than laboratory-confirmed diagnoses. To date, this is the first study to investigate the incidence of tick bite consultations and LB in England and Wales., (© 2020 Crown copyright. Zoonoses Public Health © 2020 Blackwell Verlag GmbH.)

Mapping the public health threat of tickborne pathogens requires quantification of not only the density of infected host-seeking ticks but also the rate of human exposure to these ticks. To efficiently sample a high number of persons in a short time, we used a mass-participation outdoor event. In June 2014, we sampled ≈500 persons competing in a 2-day mountain marathon run across predominantly tick-infested habitat in Scotland. From the number of tick bites recorded and prevalence of tick infection with Borrelia burgdoferi sensu lato and B. miyamotoi, we quantified the frequency of competitor exposure to the pathogens. Mass-participation outdoor events have the potential to serve as excellent windows for epidemiologic study of tickborne pathogens; their concerted use should improve spatial and temporal mapping of human exposure to infected ticks.

Tick-borne diseases pose an increasingly important public health problem in Europe. Rodents are the reservoir host for many tick-transmitted pathogens, including Anaplasma phagocytophilum and Babesia microti, which can cause human granulocytic anaplasmosis and babesiosis, respectively. To estimate the presence of these pathogens in rodents in Finland, we examined blood samples from 151 bank voles (Myodes glareolus) and demonstrate, for the first time, that A. phagocytophilum and B. microti commonly infect bank voles (in 22% and 40% of animals, respectively) in Finland. Sequence analysis of a fragment of 18S rRNA showed that the B. microti strain isolated was identical to the Munich strain, which is considered to be nonzoonotic. The A. phagocytophilum strain (based on a fragment of the msp4 gene) was identical to one found earlier in rodents in the United Kingdom that is transmitted by the tick Ixodes trianguliceps, all the life stages of which feed on small mammals. The infection probability of B. microti in the bank voles was the greater the older the individual was, and males were more often infected than females. A. phagocytophilum infection probability first increased and then decreased with the age of individual without any difference between sexes. While these pathogens presumably pose a limited zoonotic risk to humans in Finland, they might have important interactions with other rodent pathogens and therefore affect infection dynamics of, for example, zoonotic pathogens.

Infections by the ixodid tick-transmitted bacterial pathogen Anaplasma phagocytophilum are common in domestic ruminants and cervids in the coastal areas of southern Norway. Previous experimental work has shown that A. phagocytophilum strains recovered from red deer (Cervus elaphus) are infective in lambs, but epidemiological links between infections in red deer and sheep have yet to be established. To address this shortfall, the present study explores the genotypic relatedness between A. phagocytophilum strains infecting sympatric red deer and sheep. Blood from 32 lambs grazing on tick-infested pasture, and blood and tissues from 8 red deer shot in proximity to these pastures were collected during the summer and autumn of 2007. The presence of A. phagocytophilum in these samples was determined by PCR-based methods, and genotyping of detected strains was performed using comparative sequence analysis of 16S rDNA and msp4 fragments. A. phagocytophilum DNA was detected in 12 lambs and 7 red deer, 11 and 4 individuals of which 16S rDNA and msp4 sequence data were obtained from, respectively. A total of 9 genotypes were delineated, and only different individuals of the same host species were infected with indistinguishable A. phagocytophilum genotypes. Although 3 of the red deer-infecting genotypes belonged to a cluster of exclusively deer-associated strains phylogenetically remote from those commonly encountered in sheep, one red deer-infecting genotype, although unique, clustered tightly with genotypes associated with a wide range of hosts including sheep., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

Lyme borreliosis is rapidly emerging in the United Kingdom, with over 1000 cases per annum now reported. Lyme borreliosis is caused by the Borrelia burgdorferi sensu lato (s.l.) group of spirochetes, which are transmitted by ixodid ticks. In the United Kingdom, Ixodes ricinus is recognized as the principal vector of the spirochetes, and this tick species is widely distributed across the country. However, as yet, it is unclear whether the distribution of B. burgdorferi essentially mirrors that of its vector, or if there are marked differences between the 2. The aim of this survey was to investigate the prevalence of B. burgdorferi in I. ricinus populations across northern England, north Wales, and the Scottish Border region. We surveyed for questing I. ricinus nymphs and adults at 17 sites, encountering ticks at 12. At 8 sites, large numbers (>160) ticks were collected, and at 3 of these sites B. burgdorferi infection prevalence was significantly higher (>7.5%) than the other 5 (<1.0%). Habitat type was associated with B. burgdorferi prevalence, with ticks from deciduous and mixed woodland being significantly more likely to be infected than those from other habitat types. Identification of infecting Borrelia species indicated that Borrelia valaisiana was the most common and widespread species encountered. B. garinii was common at sites where infection prevalence was high, and B. afzelii was also occasionally encountered at these sites. The survey revealed a surprisingly uneven distribution of B. burgdorferi s.l. across the region, thereby indicating that the presence of ticks does not necessarily mean the presence of the pathogen. Indeed, the spirochete appears to be absent or very rare at some sites where ticks are abundant.

Bartonella are hemoparasites exploiting a range of mammals as reservoir hosts. Several species are zoonotic pathogens. Fleas, lice, and other arthropods, such as ticks, have been implicated as vectors. While the competence of ticks as vectors of Bartonella species has recently been demonstrated, the epidemiological significance of ticks as vectors of Bartonella species in wildlife populations remains unknown. We used the presence of deer at study sites to control the presence of Ixodes ricinus ticks, and used this system to determine whether I. ricinus contributes to the epidemiology of Bartonella species infections in small mammals. Ticks were present at all sites with deer, but were absent from all sites without deer; however, the abundance of ticks on small mammals did not affect the probability of wood mice being infected with Bartonella species. Data presented here indicate that I. ricinus is not involved in the transmission of Bartonella in woodland rodents.

Ticks are important vectors of numerous pathogens causing illness, fatalities, and economic loss worldwide. Infectious disease episodes are increasing, and novel tick-borne pathogens are described frequently. Identification of novel reservoir hosts and vectors of tick-borne pathogens is essential if control measures are to be successful. In South Africa, the eastern rock sengi, Elephantulus myurus , hosts a number of tick species of veterinary importance. Despite this, there remains a paucity of information regarding the tick fauna of this species, the pathogen associations of ticks that it hosts, and its role as a reservoir host of tick-borne pathogens. The current study documents the tick fauna of E. myurus and sympatric small mammal species in Limpopo Province, South Africa. The pathogen associations of ticks hosted by elephant shrews were also investigated by PCR screening of engorged nymphs for a broad range of bacterial and protozoan tick-borne infections, including Borrelia burgdorferi sensu lato and members of Apicomplexa and the order Rickettsiales. There were marked differences in tick species and abundance among host species. Elephantulus myurus was heavily, and predominantly, parasitized by an as-yet undescribed tick species that we identify as Rhipicephalus sp. near warburtoni. PCR and sequence analysis revealed the presence of Anaplasma bovis in this tick species, which may have consequences for livestock production and conservation efforts in the area where this tick species occurs.

Although the importance of rodents as reservoirs for a number of tick-borne infections is well established, comparatively little is known about the potential role of shrews, despite them occupying similar habitats. To address this, blood and tick samples were collected from common shrews (Sorex araneus) and field voles (Microtus agrestis), a known reservoir of various tick-borne infections, from sites located within a plantation forest in northern England over a 2-year period. Of 647 blood samples collected from shrews, 121 (18.7%) showed evidence of infection with Anaplasma phagocytophilum and 196 (30.3%) with Babesia microti. By comparison, of 1505 blood samples from field voles, 96 (6.4%) were positive for A. phagocytophilum and 458 (30.4%) for Ba. microti. Both species were infested with the ticks Ixodes ricinus and Ixodes trianguliceps, although they had different burdens: on average, shrews carried almost six times as many I. trianguliceps larvae, more than twice as many I. ricinus larvae, and over twice as many nymphs (both tick species combined). The finding that the nymphs collected from shrews were almost exclusively I. trianguliceps highlights that this species is the key vector of these infections in this small mammal community. These findings suggest that common shrews are a reservoir of tick-borne infections and that the role of shrews in the ecology and epidemiology of tick-borne infections elsewhere needs to be comprehensively investigated.

In the epidemiology of infectious diseases, the basic reproduction number, R0, has a number of important applications, most notably it can be used to predict whether a pathogen is likely to become established, or persist, in a given area. We used the R0 model to investigate the persistence of 3 tick-borne pathogens; Babesia microti, Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in an Apodemus sylvaticus-Ixodes ricinus system. The persistence of these pathogens was also determined empirically by screening questing ticks and wood mice by PCR. All 3 pathogens behaved differently in response to changes in the proportion of transmission hosts on which I. ricinus fed, the efficiency of transmission between the host and ticks and the abundance of larval and nymphal ticks found on small mammals. Empirical data supported theoretical predictions of the R0 model. The transmission pathway employed and the duration of systemic infection were also identified as important factors responsible for establishment or persistence of tick-borne pathogens in a given tick-host system. The current study demonstrates how the R0 model can be put to practical use to investigate factors affecting tick-borne pathogen persistence, which has important implications for animal and human health worldwide.

The emerging tick-borne pathogen Anaplasma phagocytophilum is under increasing scrutiny for the existence of subpopulations that are adapted to different natural cycles. Here, we characterized the diversity of A. phagocytophilum genotypes circulating in a natural system that includes multiple hosts and at least 2 tick species, Ixodes ricinus and the small mammal specialist I. trianguliceps. We encountered numerous genotypes, but only 1 in rodents, with the remainder limited to deer and host-seeking I. ricinus ticks. The absence of the rodent-associated genotype from host-seeking I. ricinus ticks was notable because we demonstrated that rodents fed a large proportion of the I. ricinus larval population and that these larvae were abundant when infections caused by the rodent-associated genotype were prevalent. These observations are consistent with the conclusion that genotypically distinct subpopulations of A. phagocytophilum are restricted to coexisting but separate enzootic cycles and suggest that this restriction may result from specific vector compatibility.

The importance of Ixodes ricinus in the transmission of tick-borne pathogens is well recognized in the United Kingdom and across Europe. However, the role of coexisting Ixodes species, such as the widely distributed species Ixodes trianguliceps, as alternative vectors for these pathogens has received little attention. This study aimed to assess the relative importance of I. ricinus and I. trianguliceps in the transmission of Anaplasma phagocytophilum and Babesia microti among United Kingdom field voles (Microtus agrestis), which serve as reservoir hosts for both pathogens. While all instars of I. trianguliceps feed exclusively on small mammals, I. ricinus adults feed primarily on larger hosts such as deer. The abundance of both tick species and pathogen infection prevalence in field voles were monitored at sites surrounded with fencing that excluded deer and at sites where deer were free to roam. As expected, fencing significantly reduced the larval burden of I. ricinus on field voles and the abundance of questing nymphs, but the larval burden of I. trianguliceps was not significantly affected. The prevalence of A. phagocytophilum and B. microti infections was not significantly affected by the presence of fencing, suggesting that I. trianguliceps is their principal vector. The prevalence of nymphal and adult ticks on field voles was also unaffected, indicating that relatively few non-larval I. ricinus ticks feed upon field voles. This study provides compelling evidence for the importance of I. trianguliceps in maintaining these enzootic tick-borne infections, while highlighting the potential for such infections to escape into alternative hosts via I. ricinus.

The transmission dynamics of Anaplasma phagocytophilum strains circulating within juvenile members of a sheep flock grazing on an Ixodes ricinus-infested pasture in southern Norway were monitored. PCR-based detection of the bacterial p44 fragments in the blood of 16 lambs sampled weekly for 16 weeks following their release into pasture revealed rickettsemia in all animals, with an increasing proportion of infected animals as the survey progressed. Comparison of partial msp4 sequences obtained from infected blood samples revealed 24 distinct genotypes, some of which were repeatedly encountered, occurring in up to six sheep over a 14-week period, whereas others were observed only once. Individual sheep were infected by up to five distinct genotypes, with a specific genotype being encountered for between one and three consecutive weeks, and in some sheep, genotypes detected early in the study were also present in later samples. In general, detection of A. phagocytophilum by PCR correlated well with the observation of infected neutrophils in blood smears. Together these results reveal a previously unrecognized diversity of A. phagocytophilum strains simultaneously circulating within an infected population in an area of endemicity and are consistent with a remarkably dynamic transmission of strains among infected animals.

The presence of haemoparasites belonging to the taxa Anaplasma, Bartonella and Trypanosoma was determined among 76 common shrews (Sorex araneus) from Northwest England. Anaplasma phagocytophilum DNA was recovered from the blood of 1 shrew (1.3%), with the amplified 16S rRNA sequence identical to one previously reported from a bank vole (Clethrionomys glareolus). Trypanosoma spp. DNA was detected in 9 shrews (11.8%), the amplified 18S rDNA fragments being indistinguishable from one another, and distinct from previously published data. This represents the first report of trypanosome infection in S. araneus and suggests they are susceptible to an uncharacterized Trypanosoma species. Blood from 11 shrews (14.5%) yielded Bartonella spp., with characterization of isolates using comparative sequence analysis of partial gltA and 16S-23S rRNA intergenic spacer regions revealing 2 different genotypes. Phylogenetic inference from alignment of partial gltA sequences found that both UK S. araneus types formed a well-supported cluster with Bartonella sp. isolated from S. araneus in Sweden. No significant effect of host age, sex, or year of collection was found on prevalence of Bartonella or trypanosome infections. The results of this survey demonstrate that common shrews in the UK are susceptible to haemoparasitic infections, at prevalences similar to those reported from sympatric rodents.

Anaplasma phagocytophilum is a widely distributed tick-borne pathogen of humans, livestock, and companion animals. We used in silico methods to identify 10 variable-number tandem-repeat (VNTR) loci within the genome sequence of the A. phagocytophilum HZ strain and used these data to develop a multilocus VNTR-based typing scheme for the species. Having confirmed the stability of four of the loci in replicates of the A. phagocytophilum strain that had been subjected to different numbers of passages through cell cocultures in vitro, we then used this typing scheme to discriminate between 20 A. phagocytophilum strains of diverse geographical and host provenances. Extensive diversity was found at each of the four loci studied, with total allele numbers ranging from 13 to 18 and Hunter-Gaston discriminatory index values ranging from 0.93 to 0.99. Only 2 of the 20 strains examined shared alleles at all four loci. The discriminatory power of VNTR analysis was found to be greater than that of either partial msp4 or 16S rRNA gene sequence comparison. The extremely high sensitivity of this novel approach to the genetic fingerprinting of A. phagocytophilum strains should serve well in molecular epidemiological studies of infection transmission, particularly when fine-scale strain delineation is required.

Many zoonotic disease agents are transmitted between hosts by arthropod vectors, including fleas, but few empirical studies of host-vector-microparasite dynamics have investigated the relative importance of hosts and vectors. This study investigates the dynamics of 4 closely related Bartonella species and their flea vectors in cyclic populations of field voles (Microtus agrestis) over 3 years. The probability of flea infestation was positively related to field vole density 12 months previously in autumn, but negatively related to more recent host densities, suggesting a dilution effect. The 4 Bartonella species exhibited contrasting dynamics. Only B. grahamii, showed a distinct seasonal pattern. Infection probability increased with field vole density for B. doshiae, B. taylorii and BGA (a previously unidentified species) and with density of coexisting wood mice for B. doshiae and B. grahamii. However, only the infection probability of BGA in spring was related to flea prevalence. B. doshiae and BGA were most common in older animals, but the other 2 were most common in non-reproductive hosts. Generally, host density rather than vector abundance appears most important for the dynamics of flea-transmitted Bartonella spp., possibly reflecting the importance of flea exchange between hosts. However, even closely related species showed quite different dynamics, emphasising that other factors such as population age structure can impact on zoonotic risk.

The importance of wild rodents as reservoirs of zoonotic tick-borne pathogens is considered low in the United Kingdom because, in studies to date, those parasitized by exophilic Ixodes ricinus ticks carry almost exclusively larvae and thus have a minor role in transmission cycles. In a cross-sectional study, 11 (6.7%) of 163 field voles (Microtus agrestis) captured at field sites in Northern England were PCR-positive for Anaplasma phagocytophilum. The voles were found to act as hosts for both larval and nymphal I. ricinus and all stages of the nidicolous tick I. trianguliceps, and eight individuals were infested with ticks of both species at the same time. Two of 158 larval and one of 13 nymphal I. ricinus, as well as one of 14 larval and one of 15 nymphal I. trianguliceps collected from the rodents were PCR-positive. These findings suggest that habitats where field voles are abundant in the United Kingdom may pose a risk of A. phagocytophilum infection because (i) field voles, the most abundant terrestrial mammal in the United Kingdom, may be a competent reservoir; (ii) the field voles are hosts for both nymphal and larval ixodid ticks so they could support endemic cycles of A. phagocytophilum; and (iii) they are hosts for nidicolous I. trianguliceps, which may alone maintain endemic cycles, and exophilic I. ricinus ticks, which could act as a bridge vector and transmit infections to humans and domesticated animals.

Postmortem examinations of 49 red squirrels (Sciurus vulgaris) found dead on the Isle of Wight revealed the presence of a Hepatozoon species in 18 of them (37 per cent). The prevalence of infection was highest in subadult animals and no juveniles were infected. The prevalence was higher in the squirrels dying from natural causes (nine of 12) than in squirrels killed in road accidents (seven of 27). The weight of infection varied, and there were heavy infections in squirrels dying from toxoplasmosis and bacterial pneumonia. A PCR-based assay was used to identify the presence of Hepatozoon species DNA in the lungs, and immunoperoxidase staining was used to confirm the identity of schizonts observed in histological sections. The nucleotide base sequence of the PCR products indicated that the organism was a novel species closely related to, but distinct from, Hepatozoon erhardovae of bank voles (Clethrionomys glareolus).

The potential of biological invasions to threaten native ecosystems is well recognized. Here we describe how an introduced species impacts on native host-parasite dynamics by acting as an alternative host. By sampling sites across an invasion front in Ireland, we quantified the influence of the introduced bank vole (Clethrionomys glareolus) on the epidemiology of infections caused by flea-transmitted haemoparasites of the genus Bartonella in native wood mice (Apodemus sylvaticus). Bartonella infections were detected on either side of the front but occurred exclusively in wood mice, despite being highly prevalent in both rodent species elsewhere in Europe. Bank vole introduction has, however, affected the wood mouse-Bartonella interaction, with the infection prevalence of both Bartonella birtlesii and Bartonella taylorii declining significantly with increasing bank vole density. Whilst flea prevalence in wood mice increases with wood mouse density in areas without bank voles, no such relationship is detected in invaded areas. The results are consistent with the dilution effect hypothesis. This predicts that for vector-transmitted parasites, the presence of less competent host species may reduce infection prevalence in the principal host. In addition we found a negative relationship between B. birtlesii and B. taylorii prevalences, indicating that these two microparasites may compete within hosts.

Postmortem examinations of four pine martens which had died as a result of road accidents in Scotland revealed focal, granulomatous lesions in the heart and skeletal muscles of three of them. An immunoperoxidase staining technique showed that the lesions were due to infection with Hepatozoon species. A PCR-based assay was used to confirm the presence of Hepatozoon DNA in the infected tissues. The nucleotide base sequence of the PCR products suggested that the infecting organism was probably a new species of Hepatozoon, most closely related to, but distinct from, Hepatozoon canis. The pine martens were in good physical condition and there was no indication that the infection was causing ill health.

Bartonella species are increasingly associated with a range of human and animal diseases. Despite this, we have a poor understanding of the ecology and epidemiology of many species, especially those circulating in wild populations. Previous studies have demonstrated that a diverse range of Bartonella species are abundant in wild rodent populations; little is known regarding their modes of transmission, although both direct and indirect routes have been suggested. In this study, with bank voles (Clethrionomys glareolus) as the host species, we demonstrate that the rodent flea Ctenophthalmus nobilis is a competent vector of at least two Bartonella species, B. grahamii, which has previously been associated with human infection, and B. taylorii. In contrast, no evidence of either horizontal or vertical transmission was seen in bank voles inoculated with B. taylorii maintained in an arthropod-free environment; this finding suggests that fleas may be essential for transmitting some Bartonella species.

Anaplasma phagocytophilum is a tick-borne bacterium that is zoonotic in the USA and southern Europe, but although the bacterium is endemic in the UK, no cases of clinical human disease have yet been detected in that country. Potential genomic differences amongst UK and USA isolates were investigated by comparing partial 16S rRNA gene and p44 paralogue sequences amplified by PCR from 10 UK ruminant or tick isolates, with published sequences from USA isolates. No significant clustering among the isolates was resolved by phylogenetic analysis of alignments containing 16S rRNA gene sequences. The structure of predicted proteins encoded by p44 paralogues, amplified from 81 clones obtained from the UK isolates, was similar to that described previously for paralogues from USA isolates. Paralogue sequences did not obviously cluster by country, host species or isolate, but most paralogues were 30-70 % similar, making meaningful alignments difficult. Some p44 paralogues from different isolates formed clusters of sequences that were more than 90 % similar to one another ('similarity groups'). The paralogues in each cluster were particularly similar in gene regions most likely to code for ligands. In the sample studied, 95 % of the similarity groups comprised paralogues from either USA or UK isolates only and occurred with greater frequency amongst paralogues from USA rather than UK isolates. These findings raise the hypothesis that sequences of paralogues in similarity groups may provide an index of adaptation of different 'strains' of A. phagocytophilum to specific reservoir hosts in different geographical locations, and any associations with infectivity for different species including humans.

We investigated the reservoir role of European wild rodents for Anaplasma phagocytophila using polymerase chain reaction (PCR) analysis of blood collected from individually tagged rodents captured monthly over 2 years. The only tick species observed in the woodland study site was Ixodes trianguliceps, and ruminant reservoir hosts were not known to occur. A. phagocytophila infections were detected in both bank voles and wood mice but were restricted to periods of peak nymphal and adult tick activity. Most PCR-positive rodents were positive only once, suggesting that rodent infections are generally short-lived and that ticks rather than rodents may maintain the infection over winter. Bank voles were more likely to be PCR positive than wood mice, possibly because detectable infections are longer lived in bank voles. This study confirms that woodland rodents can maintain A. phagocytophila in Great Britain in the absence of other reservoir hosts and suggests that I. trianguliceps is a competent vector.

Phylogenetic analyses of bartonella have suggested divergence between bartonellae that infect mammals native to the Old and New Worlds. We characterized bartonella isolated from Eastern grey squirrels (Sciurius carolinensis) in the United States and from grey and red squirrels (Sciurus vulgaris) in the United Kingdom by nucleotide sequence comparison (gltA and groEL). Isolates from grey squirrels in the United States and the United Kingdom were identical, and most similar to Bartonella vinsonii, a species associated with New World rodents. A single and novel bartonella genotype was obtained from all 12 red squirrel isolates. Although grey squirrels were first introduced into the United Kingdom over 125 years ago, they continue to be infected solely by the bartonella associated with grey squirrels native to the United States. These results illustrate that exotic species may be accompanied by the introduction and maintenance, over many generations, of their microparasites.

The strongest evidence for host specificity of mammalian trypanosomes comes from parasites of the subgenus Trypanosoma (Herpetosoma). Laboratory studies have shown that T. (Herpetosoma) species will not infect an alternative host. However, this has not been demonstrated in wild populations. We screened 560 bank voles (Clethrionomys glareolus) and 148 wood mice (Apodemus sylvaticus) for trypanosomes by PCR amplification of the 18S rRNA gene. In total, 109 (19%) bank voles and 12 (8%) wood mice were infected. A HaeIII restriction site was discovered that could be used to discriminate between T. (H.) evotomys of the bank vole and T. (H.) grosi of the wood mouse. All the parasites in the bank voles were identified as T. (Herpetosoma) evotomys by RFLP-PCR. Out of the 12 wood mouse infections 10 were due to T. grosi. Two of the wood mice were infected with parasites with a novel genotype that was most similar to those of T. evotomys and T. microti of voles. Fifty-six fleas collected from the rodents were also screened for trypanosomes; 9 were infected with T. evotomys and 1 with T. grosi. One of the fleas infected with T. evotomys was collected from a wood mouse.

In a longitudinal study in a UK upland site, 38% of adult sheep were detected as infected with the tick-borne bacterium Ehrlichia phagocytophila by PCR of blood samples. Infection prevalence declined significantly with sheep age but varied significantly and non-linearly with the number of adult Ixodes ricinus ticks feeding per sheep. These findings suggested that under conditions of natural repeated tick-borne challenge sheep remain partially susceptible to re-infections, but the likelihood of re-infection depended on the numbers of feeding ticks. Transmission efficiency from sheep to immature ticks also varied significantly and non-linearly with the number of adult ticks feeding per sheep: transmission efficiency was almost zero in sheep with low adult tick infestations rising to 30% at certain levels of adult tick infestation. Infection intensity in infected engorged immature ticks also varied with the number of adult ticks feeding per sheep, but neither prevalence nor intensity of infection in engorged ticks were related to sheep blood PCR result. These findings suggest that variation in the numbers of ticks feeding per sheep may influence E. phagocytophila transmission by direct effects on transmission at the tick-host interface.

Two patients presented with hard black eschars covering granulating ulcers. The ulcers healed within 6 weeks to leave small scars. The diagnosis of cowpox was confirmed by serology in both cases and in addition by polymerase chain reaction in the first. The source of infection was likely to be a rodent in the first case whilst the second was more typical in being transmitted by a cat., (Copyright 2000 The British Association of Plastic Surgeons.)

It is generally accepted that the reservoir hosts of cowpox virus are wild rodents, although direct evidence for this is lacking for much of the virus's geographic range. Here, through a combination of serology and PCR, we demonstrate conclusively that the main hosts in Great Britain are bank voles, wood mice and short-tailed field voles. However, we also suggest that wood mice may not be able to maintain infection alone, explaining the absence of cowpox from Ireland where voles are generally not found. Infection in wild rodents varies seasonally, and this variation probably underlies the marked seasonal incidence of infection in accidental hosts such as humans and domestic cats.

Some thermophilic species of Bacillus were characterized using biochemical tests, antibiotic sensitivity, bacteriocin and bacteriophage sensitivity, esterase patterns, DNA hybridization and % G+C content. The three caldo-active strains of bacilli isolated by Heinen (1971) were compared with strains of B. stearothermophilus. Eight of the strains examined showed characteristics which enabled them to be placed in the three main taxonomic groups suggested by Walker & Wolf (1971). Two strains showed characteristics of both groups 1 and 3. Examination of genotype data showed taxonomic groupings which differed from those based on phenotypic characterization.

A protocol for the rapid purification of the glycerol dehydrogenase (glycerol: NAD+ 2-oxidoreductase, EC 1.1.1.6) from the thermophile Bacillus stearothermophilus has been developed using a combination of chromatographic techniques including affinity chromatography on a Sepharose-immobilised triazine dye (Procion red, HE3B, ICI). Substrate specificity has been examined and Km values determined. The protein has been shown to have an oligomeric Mr of approx. 180,000 and consists of four identical subunits of Mr 42,000. Exposure to chelating agents (e.g., EDTA) leads to total loss of activity; the EDTA-inactivated enzyme can be reactivated by Zn2+ and requires 1 mol equivalent of zinc per subunit for full catalytic activity. Other divalent cations such as Cd2+ and Co2+ will reactivate the apo-enzyme but yields an enzyme of lower specific activity. The enzyme binds 1 equivalent of NADH per subunit and during catalysis transfers the 4-pro-R hydride from the nicotinamide ring of the reduced-coenzyme to the substrate. Glycerol increases the dissociation constant for the interaction between NADH and Zn-metallo-glycerol dehydrogenase (ZnGDH) but has no effect on the equilibrium between NADH and metal-depleted enzyme.