Rodentolepis straminea (Cestoda: Hymenolepididae) in an urban population of Apodemus sylvaticus in the UK.

The presence of the cyclophyllidean cestode Rodentolepis straminea (Cestoda: Hymenolepididae), was confirmed by molecular DNA analysis from a wood mouse (Apodemus sylvaticus) population inhabiting urban woodland in Salford, Greater Manchester (UK) with a prevalence of 27.8%. It would appear that the only previously published record of this species in A. sylvaticus in the British Isles is that from south-west Ireland, where 24% of the wood mice examined were infected with R. straminea. This species has been recorded in studies on A. sylvaticus in continental Europe. The current report represents a new record for R. straminea on mainland Britain and a first study of helminth parasites in an urban wood mouse population.

Mycobacterium microti tuberculosis in its maintenance host, the field vole (Microtus agrestis): characterization of the disease and possible routes of transmission.

The field vole (Microtus agrestis) is a known maintenance host of Mycobacterium microti. Previous studies have shown that infected animals develop tuberculosis. However, the disease is also known in cats and is sporadically reported from humans and other mammalian species. We examined trapped field voles from an endemic area, using a range of diagnostic approaches. These confirmed that a combination of gross and histological examination with culture is most appropriate to identify the true prevalence of the disease, which was shown to be more than 13% at times when older animals that have previously been shown to be more likely to develop the disease dominate the population. The thorough pathological examination of diseased animals showed that voles generally develop systemic disease with most frequent involvement of spleen and liver, followed by skin, lymph nodes, and lungs. The morphology of the lesions was consistent with active disease, and their distribution suggested skin wounds or oral and/or aerogenic infection as the main portal of entry. The demonstration of mycobacteria in open skin lesions, airways, and salivary glands indicated bacterial shedding from the skin and with sputum and saliva. This suggests not only the environment but also direct contact and devouring as likely sources of infection.

Bartonella species as a cause of infective endocarditis in the UK.

Bartonella spp. are increasingly implicated in infectious endocarditis cases in the UK. Herein, we attempted to quantify their role in this syndrome and explored the epidemiology of Bartonella-associated endocarditis in the UK. Between November 2005 and October 2010, samples from 685 endocarditis patients were submitted to the Health Protection Agency for Bartonella serology. Serological evidence of infection was obtained for 57 (8·3%) patients. PCR-based evidence of infection was obtained from 13 out of 14 patients for whom heart valve tissue was available, with Bartonella quintana implicated in 12 cases and B. henselae in one. Six patients with B. quintana endocarditis were recent immigrants into the UK, of whom four lived in poor socioeconomic conditions. These results indicate that Bartonella is a not uncommon cause of endocarditis in the UK and should be considered particularly in patients raised in eastern Europe and/or with a history of homelessness or alcoholism.

Recurrent bacteraemia in sheep infected persistently with Anaplasma phagocytophilum.

Following experimental or natural infection with Anaplasma phagocytophilum, the causative agent of tick-borne fever (TBF), sheep may be infected persistently for several months or years. In the present study, quantitative real-time polymerase chain reaction was used to investigate the duration and magnitude of primary bacteraemia and to establish whether the organism is present continuously in the peripheral blood after the period of primary bacteraemia and the cessation of clinical signs. Persistent infection was characterized by a clearly defined period of primary bacteraemia followed by recurrent cycles of bacteraemia, usually lasting a few days and of lower magnitude, interspersed by negative periods of variable duration in which bacterial DNA could not be detected. During a 150-day period of consecutive sampling of four sheep, A. phagocytophilum was detected on 64.25 ± 4.9 occasions, which means that on average bacterial DNA was detected in 42.8 ± 3.3 percent of all samples, with the positive days falling into 15-20 distinct cycles. Primary bacteraemia lasted for 15.5 ± 2.33 days, but secondary and subsequent cycles of bacteraemia were short-lived, with 61% of the cycles lasting only 1-2 days and 39% lasting for 3 or more days. Secondary and subsequent cycles of bacteraemia were not accompanied by febrile responses or other clinical features of TBF. For three animals, bacterial DNA was detected at 311, 318 and 358 days post infection, indicating the long-term persistence of A. phagocytophilum within peripheral blood.

Multilocus sequence typing of human and canine C. upsaliensis isolates.

Risk of Campylobacter infection in humans has been associated with many sources, including dogs. C. upsaliensis is the most common species found in canines, and has been occasionally isolated from symptomatic humans. This study aimed to investigate the genetic diversity of 41 C. upsaliensis isolates carried by dogs and from nine isolates carried by humans using Multilocus sequence typing (MLST). We identified considerable genetic diversity amongst the C. upsaliensis isolates from both dogs and humans, identifying 45 different sequence types (STs). All STs were new, apart from that of the reference strain. Only three STs were found in more than one isolate: ST-72 (2 isolates), ST-98 (2 isolates) and ST-104 (3 isolates). ST-104 was the only ST to be encountered in both dogs and humans. Thirty-one of the 45 STs were assigned to one of 13 clonal complexes (CCs). Four of these CCs contained STs originating from both humans and dogs. None of the CCs contained exclusively human isolates, and two isolates from dogs within the same kennel belonged to the same CC. The large amount of diversity found in both dog and human isolates of C. upsaliensis, combined with the relatively small database, made it difficult to assign strains to sources of infection. This emphasizes the need to increase the size of the database. Dog and human isolates occasionally grouped together, however there were insufficient human-derived isolates to determine whether or not dogs are a common source of infection. Although C. upsaliensis infection is rare in humans, dogs still remain a potential source, and are therefore a possible zoonotic risk. Further work is needed to investigate the epidemiology of C. upsaliensis infection in humans.

Isolation of a novel Campylobacter jejuni clone associated with the bank vole, Myodes glareolus.

Campylobacter jejuni can be isolated from different animal hosts. Various studies have used multilocus sequence typing to look for associations between particular clones of C. jejuni and specific hosts. Here, we describe the isolation of a novel clone (sequence type 3704 [ST-3704]) of C. jejuni associated with the bank vole (Myodes glareolus).

Development and use of real-time PCR to detect and quantify Mycoplasma haemocanis and "Candidatus Mycoplasma haematoparvum" in dogs.

Two canine haemoplasma species have been recognised to date; Mycoplasma haemocanis (Mhc), which has been associated with anaemia in splenectomised or immunocompromised dogs, and "Candidatus Mycoplasma haematoparvum" (CMhp), recently described in an anaemic splenectomised dog undergoing chemotherapy. The study aim was to develop quantitative real-time PCR assays (qPCRs) incorporating an endogenous internal control to detect Mhc and CMhp and to apply these assays to DNA samples extracted from canine blood collected in Northern Tanzania (n=100) and from dogs presented to a Trinidadian veterinary hospital (n=185). QPCRs specific for Mhc and CMhp were designed using 16S rRNA gene sequence data, and each was duplexed with an assay specific for canine glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The assays detected < or =10 copies of a sequence-specific haemoplasma plasmid per reaction and neither assay showed cross-reactivity with 10(6) copies of the sequence-specific plasmid from the non-target canine haemoplasma species. Nineteen of the 100 Tanzanian samples (19%) were positive for Mhc alone and one (1%) was dually infected. One Trinidadian sample was negative for canine GAPDH DNA and was excluded from the study. Of the 184 remaining Trinidadian samples, nine (4.9%) were positive for Mhc alone, five (2.7%) for CMhp alone, and two (1.1%) dually infected. This is the first report of canine haemoplasma qPCR assays that use an internal control to confirm the presence of amplifiable sample DNA, and their application to prevalence studies. Mhc was the most commonly detected canine haemoplasma species.

Prevalence of Campylobacter spp. in a cross-sectional study of dogs attending veterinary practices in the UK and risk indicators associated with shedding.

Campylobacteriosis is a major cause of gastroenteritis in humans and some studies have suggested that dog ownership is a risk factor for the condition. To determine the prevalence, species distribution, and risk indicators for Campylobacter spp. infecting dogs attending veterinary practices in UK, faecal samples were collected in a cross-sectional study from 249 dogs with and without clinical signs. The prevalence of Campylobacter spp. was 38% (95% CI 32, 44), with Campylobacter upsaliensis accounting for 94 (98%) of the isolates and Campylobacter jejuni for the remainder. Multivariable analysis indicated that younger dogs were more likely to carry C. upsaliensis and the high prevalence of this pathogen supports the hypothesis that dogs, particularly younger animals, may be an important source of C. upsaliensis infection for humans. However the prevalence of C. jejuni, the most common Campylobacter spp. associated with disease in humans, was low (1.2%, 95% CI 0.3, 3).

Risk factors for the carriage of Campylobacter upsaliensis by dogs in a community in Cheshire.

Samples of faeces were taken from 183 healthy pet dogs in a census-based, cross-sectional study in Cheshire; culture methods were used to detect any Campylobacter species and a direct PCR was used to detect Campylobacter upsaliensis. Forty-six of the dogs were positive for C upsaliensis by either culture or direct PCR, giving a prevalence of 25.1 per cent (95 per cent confidence interval [CI] 19.0 to 32.1 per cent). One sample was positive by culture for Campylobacter jejuni (95 per cent CI 0.0 to 3.0 per cent) and one for Campylobacter lari. Multivariable logistic regression identified risk factors for the carriage of C upsaliensis by a dog as: living with another dog that also carried C upsaliensis; being small rather than medium-sized; being less than three years old; living in a household that kept fish; being fed commercial dog treats; and being fed human food titbits, particularly in the dog's bowl.

Mycobacterium microti: More diverse than previously thought.

Mycobacterium microti is a member of the Mycobacterium tuberculosis complex of bacteria. This species was originally identified as a pathogen of small rodents and shrews and was associated with limited diversity and a much reduced spoligotype pattern. More recently, specific deletions of chromosomal DNA have been shown to define this group of organisms, which can be identified by the absence of chromosomal region RD1(mic). We describe here the molecular characteristics of 141 strains of the Mycobacterium tuberculosis complex isolated in Great Britain over a 14-year period. All strains have characteristic loss of some spoligotype spacers and characteristic alleles at the ETR-E and ETR-F variable-number tandem-repeat (VNTR) loci, and a sample of these strains was deleted for regions RD7, RD9, and RD1(mic) but intact for regions RD4 and RD12. We therefore identified these strains as M. microti and show that they have much more diverse spoligotype patterns and VNTR types than previously thought. The most common source of these strains was domestic cats, and we show that the molecular types of M. microti are geographically localized in the same way that molecular types of Mycobacterium bovis are geographically localized in cattle in the United Kingdom. We describe the pathology of M. microti infection in cats and suggest that the feline disease is a spillover from a disease maintained in an unknown wild mammal, probably field voles. The location of the cats with M. microti infection suggests that they do not overlap geographically with the strains of Mycobacterium bovis in Great Britain.

Tyzzer's disease in a Eurasian otter (Lutra lutra) in Scotland.

A Eurasian otter (Lutra lutra) cub found in weak condition on the Isle of Harris, Scotland, developed bilateral corneal oedema 16 days after being admitted to a rehabilitation centre. It died unexpectedly on day 26. On postmortem examination, there was excess clear fluid in the body cavities and the liver was swollen with numerous pale focal lesions and petechial haemorrhages throughout. Histopathological examination revealed bundles of bacilli morphologically typical of Clostridium piliforme within hepatocytes. Comparative analysis of the nucleotide base sequence of a 16S rdna fragment amplified from the infected liver tissue revealed that it was identical to a C piliforme 16S rdna sequence. The possibility of concurrent infection with canine adenovirus type 1 was considered but none of the characteristic histopathological lesions was observed and examination of the liver by transmission electron microscopy was negative for virus particles. This appears to be the first record of Tyzzer's disease in an otter and the first in a wild animal in Britain.

Relative importance of Ixodes ricinus and Ixodes trianguliceps as vectors for Anaplasma phagocytophilum and Babesia microti in field vole (Microtus agrestis) populations.

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.

Parasite interactions in natural populations: insights from longitudinal data.

The physiological and immunological state of an animal can be influenced by current infections and infection history. Consequently, both ongoing and previous infections can affect host susceptibility to another parasite, the biology of the subsequent infection (e.g. infection length) and the impact of infection on host morbidity (pathology). In natural populations, most animals will be infected by a succession of different parasites throughout the course of their lives, with probably frequent concomitant infections. The relative timing of different infections experienced by a host (i.e. the sequence of infection events), and the effects on factors such as host susceptibility and host survival, can only be derived from longitudinal data on individual hosts. Here we review some of the evidence for the impact of co-infection on host susceptibility, infection biology and pathology focusing on insights obtained from both longitudinal studies in humans and experiments that explicitly consider the sequence of infection. We then consider the challenges posed by longitudinal infection data collected from natural populations of animals. We illustrate their usefulness using our data of microparasite infections associated with field vole (Microtus agrestis) populations to examine impacts on susceptibility and infection length. Our primary aim is to describe an analytical approach that can be used on such data to identify interactions among the parasites. The preliminary analyses presented here indicate both synergistic and antagonistic interactions between microparasites within this community and emphasise that such interactions could have significant impacts on host-parasite fitness and dynamics.

Haemoparasites of common shrews (Sorex araneus) in Northwest England.

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.

Contrasting dynamics of Bartonella spp. in cyclic field vole populations: the impact of vector and host dynamics.

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.

Sympatric Ixodes trianguliceps and Ixodes ricinus ticks feeding on field voles (Microtus agrestis): potential for increased risk of Anaplasma phagocytophilum in the United Kingdom?

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.

Hepatozoon species infection in wild red squirrels (Sciurus vulgaris) on the Isle of Wight.

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).

Molecular evidence of tick-transmitted infections in dogs and cats in the United Kingdom.

PCR analysis was used to determine the prevalence of tick-transmitted infections in 120 systemically ill dogs and 60 cats recruited over a period of three months from 52 veterinary practices in the UK. The animals had not travelled outside the UK and had one or more of the following clinical criteria: acute or recurrent pyrexia, anaemia and/or thrombocytopenia, polyarthritis/muscle pain, splenomegaly/lymphadenopathy, and intraocular inflammation with systemic signs. Blood samples from the animals were tested for the presence of DNA from Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum by using simple PCR targeting. B. burgdorferi sensu lato was detected in five dogs and two cats, and A. phagocytophilum was detected in one dog and one cat. These results provide the first molecular evidence of naturally occurring B. burgdorferi sensu lato infection in cats in the UK and confirm that A. phagocytophilum infection is present in cats. There were no statistically significant associations between the infections and the clinical signs shown by the dogs and cats.