Syphacia stroma (von Linstow, 1884) Morgan, 1932 and Syphacia frederici Roman, 1945 are oxyurid nematodes that parasitize two murid rodents, Apodemus sylvaticus and Apodemus flavicollis, on the European mainland. Only S. stroma has been recorded previously in Apodemus spp. from the British Isles. Despite the paucity of earlier reports, we identified S. frederici in four disparate British sites, two in Nottinghamshire, one each in Berkshire and Anglesey, Wales. Identification was based on their site in the host (caecum and not small intestine), on key morphological criteria that differentiate this species from S. stroma (in particular the tail of female worms) and by sequencing two genetic loci (cytochrome C oxidase 1 gene and a section of ribosomal DNA). Sequences derived from both genetic loci of putative British S. frederici isolates formed a tight clade with sequences from continental worms known to be S. frederici, clearly distinguishing these isolates from S. stroma which formed a tight clade of its own, distinct from clades representative of Syphacia obvelata from Mus and S. muris from Rattus. The data in this paper therefore constitute the first record of S. frederici from British wood mice, and confirm the status of this species as distinct from both S. obvelata and S. stroma.

Dobrava-Belgrade virus (DOBV) is the most pathogenic hantavirus in Europe with a case-fatality rate of up to 12%. To detect changes in risk for humans, the prevalence of antibodies to DOBV has been monitored in a population of Apodemus flavicollis in the province of Trento (northern Italy) since 2000, and a sudden increase was observed in 2010. In the 13-year period of this study, 2077 animals were live-trapped and mean hantavirus seroprevalence was 2·7% (s.e. = 0·3%), ranging from 0% (in 2000, 2002 and 2003) to 12·5% (in 2012). Climatic (temperature and precipitation) and host (rodent population density, rodent weight and sex, and larval tick burden) variables were analysed using Generalized Linear Models and multi-model inference to select the best model. Climatic changes (mean annual precipitation and maximum temperature) and individual body mass had a positive effect on hantavirus seroprevalence. Other possible drivers affecting the observed pattern need to be studied further.

Prevalence and abundance of Bartonella spp. infections were studied over a 3-year period in woodland and grassland rodents in North-Eastern Poland. Prevalence of bacterial infections was similar in the two rodent communities, with one leading host species in each habitat (46·3% in Apodemus flavicollis versus 29·1% in Myodes glareolus in forest, or 36·9% in Microtus arvalis versus 13·7% in Mi. oeconomus in grassland). Prevalence/abundance of infections varied markedly across the 3 years with 2006 being the year of highest prevalence and abundance. Infections were more common during autumn months in My. glareolus and A. flavicollis, and in juvenile and young adult (age classes 1 and 2) My. glareolus and Mi. oeconomus than in adults (age class 3). Higher prevalence and abundance of Bartonella infections were found in male A. flavicollis in comparison to females. These data are discussed in relation to the parasite genotypes identified in this region and with respect to the role of various ecological factors influencing Bartonella spp. infections in naturally infected host populations.

Free-living animals are usually inhabited by a community of parasitic species that can interact with each other and alter both host susceptibility and parasite transmission. In this study we tested the prediction that an increase in the gastrointestinal nematode Heligmosomoides polygyrus would increase the infestation of the tick Ixodes ricinus, in free-living yellow-necked mice, Apodemus flavicollis. An extensive cross-sectional trapping survey identified a negative relationship between H. polygyrus and I. ricinus counter to the prediction. An experimental reduction of the nematode infection through anthelmintic treatment resulted in an increase in tick infestation, suggesting that this negative association was one of cause and effect. Host characteristics (breeding condition and age) and habitat variables also contributed to affect tick infestation. While these results were counter to the prediction, they still support the hypothesis that interactions between parasite species can shape parasite community dynamics in natural systems. Laboratory models may act differently from natural populations and the mechanism generating the negative association is discussed.

Prevalence and abundance of Cryptosporidium spp. and Giardia spp. infections were studied over the 8-year period in 3 species of rodents in N.E. Poland (bank vole Myodes glareolus-1523; yellow-necked mouse Apodemus flavicollis- 638; common vole Microtus arvalis- 419). Prevalence was 53·8, 28·1 and 62·3% respectively for Cryptosporidium spp. and 58·3, 24·4 and 74·2% respectively for Giardia spp. Prevalence and abundance of infection varied markedly across 8 years of the study with 1998 and 2002 being years of higher prevalence and abundance, following changes in the densities of host species. The distribution of intestinal protozoa in forest rodents did not vary in the 3 isolated sites during the 4-year study. In the case of Cryptosporidium, fewer older animals carried infection and infections of the oldest bank and common voles were relatively milder. In the case of Giardia in yellow-necked mice, infections were more common in older age classes (2 and 3). The two species showed significant co-occurrence and in animals carrying both species there was a strong significant positive correlation between abundance of infection with each. These data are discussed in relation to the parasite genotypes identified in this region and in respect of the role of various ecological factors in shaping of intestinal protozoa communities.

Mathematical models of disease dynamics tend to assume that individuals within a population mix at random and so transmission is random, and yet, in reality social structure creates heterogeneous contact patterns. We investigated the effect of heterogeneity in host contact patterns on potential macroparasite transmission by first quantifying the level of assortativity in a socially structured wild rodent population (Apodemus flavicollis) with respect to the directly-transmitted macroparasitic helminth, Heligmosomoides polygyrus. We found the population to be disassortatively mixed (i.e. male mice mixing with female mice more often than same sex mixing) at a constant level over time. The macroparasite H. polygyrus has previously been shown to exhibit male-biased transmission so we used a Susceptible-Infected (SI) mathematical model to simulate the effect of increasing strengths of male-biased transmission on the prevalence of the macroparasite using empirically-derived transmission networks. When transmission was equal between the sexes the model predicted macroparasite prevalence to be 73% and infection was male biased (82% of infection in the male mice). With a male-bias in transmission ten times that of the females, the expected macroparasite prevalence was 50% and was equally prevalent in both sexes, results that both most closely resembled empirical dynamics. As such, disassortative mixing alone did not produce macroparasite dynamics analogous to those from empirical observations; a strong male-bias in transmission was also required. We discuss the relevance of our results in the context of network models for transmission dynamics and control.

Few data are available and little is known about spatial variation in post-dispersal seed removal at different levels throughout the geographic range of a plant species. Here, we compare post-dispersal seed removal by rodents within and among sites in two distinct regions, the south-eastern Spanish Mediterranean highlands and the Swiss Jura. Seed removal was assessed experimentally for four fleshy-fruited species (Berberis vulgaris, Crataegus monogyna, Rosa spp. and Taxus baccata) in heterogeneous sites with distinct microhabitats. A factorial general linear model (GLM) analysis was used to evaluate the relative influence of species-specific seed traits on removal at three spatial levels (microhabitat, site and region). In both highland ecosystems, live trapping revealed that rodents were the main seed removers: Apodemus sylvaticus was observed in both regions, whereas A. flavicollis and Clethrionomys glareolus occurred only at the Swiss sites. There was a significant difference in seed removal between regions, and the preferences of the rodents varied among plant species and microhabitats. Variation in rodent presence explained some differences in seed removal between regions and among microhabitats. Finally, the effect of rodent presence on seed removal differs due to both regional and microhabitat effects.

In Europe, the zoonotic cycle of Babesia microti has not been determined so far. Recently, B. microti was detected in Ixodes ricinus ticks in Slovenia by using molecular methods. In order to investigate the mammalian hosts of B. microti in Slovenia we collected 261 small mammals representing 11 species. They were tested for the presence of babesial parasites with a PCR assay based on the nuclear small subunit rRNA gene (nss-rDNA). The bank vole (Clethrionomys glareolus) and yellow-necked mouse (Apodemus flavicollis) were infected with B. microti. The prevalence rate was 15·9% for C. glareolus and 11·8% for A. flavicollis. Nucleotide sequences of amplified portions of B. microti nss-rDNA from C. glareolus and A. flavicollis were indistinguishable from each other and identical with those previously described in I. ricinus ticks collected in Slovenia. The results of this study represent molecular evidence of B. microti in small mammals in Europe.

Prevalence and abundance of Cryptosporodium parvum and Giardia spp. were studied in 3 species of rodents from forests and abandoned agricultural fields in N.E. Poland (Clethrionomys glareolus n = 459; Microtus arvalis n = 274; Apodemus flavicollis n = 209). Overall prevalence was consistently higher in the voles compared with A. flavicollis (70·6, 73·0 and 27·8% respectively for C. parvum and 93·9, 96·3 and 48·3% respectively for Giardia spp.). Prevalence and abundance of infection also varied markedly across 3 years with 1998 being a year of higher prevalence and abundance with both species. Fewer older animals (especially C. glareolus and M. arvalis) carried infection with C. parvum and infections in these animals were relatively milder. Although seasonal differences were significant, no consistent pattern of changes was apparent. Host sex did not influence prevalence or abundance of infection with C. parvum, but made a small contribution to a 4-way interaction (in 5-way ANOVA) with other factors in the case of Giardia spp. The 2 species co-occurred significantly and in animals carrying both parasites there was a highly significant positive correlation between abundance of infection with each, even with between-year, seasonal, host age, sex and species differences taken into account. Quantitative associations were confined to the 2 vole species in the study. These results are discussed in relation to the importance of wild rodents as reservoir hosts and sources of infection for local human communities.