Differences in the ectoparasite fauna between micromammals captured in natural and adjacent residential areas are better explained by sex and season than by type of habitat

T(r)icky Environments: Higher Prevalence of Tick-Borne Zoonotic Pathogens in Rodents from Natural Areas Compared with Urban Areas

Background: Urban areas are unique ecosystems with stark differences in species abundance and composition compared with natural ecosystems. These differences can affect pathogen transmission dynamics, thereby altering zoonotic pathogen prevalence and diversity. In this study, we screened small mammals from natural and urban areas in the Netherlands for up to 19 zoonotic pathogens, including viruses, bacteria, and protozoan parasites. Materials and Methods: In total, 578 small mammals were captured, including wood mice (Apodemus sylvaticus), bank voles (Myodes glareolus), yellow-necked mice (Apodemus flavicollis), house mice (Mus musculus), common voles (Microtus arvalis), and greater white-toothed shrews (Crocidura russula). We detected a wide variety of zoonotic pathogens in small mammals from both urban and natural areas. For a subset of these pathogens, in wood mice and bank voles, we then tested whether pathogen prevalence and diversity were associated with habitat type (i.e., natural versus urban), degree of greenness, and various host characteristics. Results: The prevalence of tick-borne zoonotic pathogens (Borrelia spp. and Neoehrlichia mikurensis) was significantly higher in wood mice from natural areas. In contrast, the prevalence of Bartonella spp. was higher in wood mice from urban areas, but this difference was not statistically significant. Pathogen diversity was higher in bank voles from natural habitats and increased with body weight for both rodent species, although this relationship depended on sex for bank voles. In addition, we detected methicillin-resistant Staphylococcus aureus, extended-spectrum beta-lactamase/AmpC-producing Escherichia coli, and lymphocytic choriomeningitis virus for the first time in rodents in the Netherlands. Discussion: The differences between natural and urban areas are likely related to differences in the abundance and diversity of arthropod vectors and vertebrate community composition. With increasing environmental encroachment and changes in urban land use (e.g., urban greening), it is important to better understand transmission dynamics of zoonotic pathogens in urban environments to reduce potential disease risks for public health.

Description of Rhipicephalus hibericus sp. nov. (Ixodoidea: Ixodidae), a species of the Rhipicephalus sanguineus group in southwestern Europe

We describe all the life stages of Rhipicephalus hibericus n. sp., provide the types, and present molecular support for a new species of the Rhipicephalus sanguineus sensu lato group, present in southwestern Europe, that has been historically confused with Rhipicephalus turanicus Pomerantzev, 1940. A new name is proposed for this taxon because it was impossible to ascribe to types of already described species in the group, deposited for more than 100 years in natural history institutions. The males have a dorsum showing deep and coarse punctations (absent in Rhipicephalus sanguineus sensu stricto) and adanal plates with large punctations (absent in R. sanguineus s.s.); the tail of the spiracular plate is as wide as the closest festoon (half the width in R. sanguineus s.s.). Females have large punctations in dorsal fields, a wide spiracular plate, and a "V" shaped genital opening; such a combination of characters cannot be found in other species of the group. Immatures are described from specimens collected on hosts (Rodentia and Eulipotyphla). Both larvae and nymphs are markedly smaller than R. sanguineus s.s. Nymphs display long, backward-projected auriculae; larvae are almost half the size of R. sanguineus s.s. The new species can hybridize with R. sanguineus s.s. in laboratory colonies producing an unfertile F2, laying brown and dry eggs that did not hatch. Phylogenetic analysis of partial coxI gene sequences placed R. hibericus in a well-supported clade with other sequences of R. sanguineus s.l. from Portugal, as a sister clade of R. sanguineus s.s. The new species does not belong to the R. turanicus group of species. Both 12S and 16S partial gene sequences were not as precise in the correct phylogenetic placement of R. hibericus, in part probably due to the existence of erroneously identified sequences in GenBank©. This description, together with the previous reinstatement of Rhipicephalus secundus and Rhipicephalus rutilus, and the description of the neotypes of R. sanguineus s.s. should help researchers to adequately identify their collections. Our findings demonstrate that R. turanicus is absent in southwestern Europe. Old collections should be re-examined to provide the actual range of the new species.

Patterns of flea infestation in rodents and insectivores from intensified agro-ecosystems, Northwest Spain

BACKGROUND

Fleas frequently infest small mammals and play important vectoring roles in the epidemiology of (re)emerging zoonotic disease. Rodent outbreaks in intensified agro-ecosystems of North-West Spain have been recently linked to periodic zoonotic diseases spillover to local human populations. Obtaining qualitative and quantitative information about the composition and structure of the whole flea and small mammal host coexisting communities is paramount to understand disease transmission cycles and to elucidate the disease-vectoring role of flea species. The aims of this research were to: (i) characterise and quantify the flea community parasiting a small mammal guild in intensive farmlands in North-West Spain; (ii) determine and evaluate patterns of co-infection and the variables that may influence parasitological parameters.

METHODS

We conducted a large-scale survey stratified by season and habitat of fleas parasitizing the small mammal host guild. We report on the prevalence, mean intensity, and mean abundance of flea species parasitizing Microtus arvalis, Apodemus sylvaticus, Mus spretus and Crocidura russula. We also report on aggregation patterns (variance-to-mean ratio and discrepancy index) and co-infection of hosts by different flea species (Fager index) and used generalized linear mixed models to study flea parameter variation according to season, habitat and host sex.

RESULTS

Three flea species dominated the system: Ctenophthalmus apertus gilcolladoi, Leptopsylla taschenbergi and Nosopsyllus fasciatus. Results showed a high aggregation pattern of fleas in all hosts. All host species in the guild shared C. a. gilcolladoi and N. fasciatus, but L. taschenbergi mainly parasitized mice (M. spretus and A. sylvaticus). We found significant male-biased infestation patterns in mice, seasonal variations in flea abundances for all rodent hosts (M. arvalis, M. spretus and A. sylvaticus), and relatively lower infestation values for voles inhabiting alfalfas. Simultaneous co-infections occurred in a third of all hosts, and N. fasciatus was the most common flea co-infecting small mammal hosts.

CONCLUSIONS

The generalist N. fasciatus and C. a. gilcolladoi dominated the flea community, and a high percentage of co-infections with both species occurred within the small mammal guild. Nosopsyllus fasciatus may show higher competence of inter-specific transmission, and future research should unravel its role in the circulation of rodent-borne zoonoses.

Molecular investigation of vector-borne parasites in wild micromammals, Barcelona (Spain)

Information about the role of micromammals in the epidemiology of Leishmania infantum and Babesia sp. in southern Europe is scarce. Wild micromammals were captured in natural areas in the Barcelona province (NE Spain) in 2011 and analysed by real-time PCR for the presence of DNA of Piroplasmida (n = 253) and Leishmania infantum (n = 166). The wood mouse (Apodemus sylvaticus) was the most abundant species, but all specimens tested negative for L. infantum, for which two out of 15 (13.3%) white-toothed shrews (Crocidura russula) and one out of 23 (4.3%) Algerian mice (Mus spretus) resulted positive. No individual was positive for Piroplasmida DNA. The role of wild micromammals in the epidemiology of these parasites in the study area seems negligible.

Drivers of flea (Siphonaptera) community structure in sympatric wild carnivores in northwestern Mexico

Host identity, habitat type, season, and interspecific interactions were investigated as determinants of the community structure of fleas on wild carnivores in northwestern Mexico. A total of 540 fleas belonging to seven species was collected from 64 wild carnivores belonging to eight species. We found that the abundances of some flea species are explained by season and host identity. Pulex irritans and Echidnophaga gallinacea abundances were significantly higher in spring than in fall season. Flea communities on carnivore hosts revealed three clusters with a high degree of similarity within each group that was explained by the flea dominance of E. gallinacea, P. simulans, and P. irritans across host identity. Flea abundances did not differ statistically among habitat types. Finally, we found a negative correlation between the abundances of three flea species within wild carnivore hosts. Individual hosts with high loads of P. simulans males usually had significantly lower loads of P. irritans males or tend to have lower loads of E. gallinacea fleas and vice-versa. Additionally, the logistic regression model showed that the presence of P. simulans males is more likely to occur in wild carnivore hosts in which P. irritans males are absent and vice-versa. These results suggest that there is an apparent competitive exclusion among fleas on wild carnivores. The study of flea community structure on wild carnivores is important to identify the potential flea vectors for infectious diseases and provide information needed to design programs for human health and wildlife conservation.

Risk factors of Leptospira infection in Mediterranean periurban micromammals

Urbanization of natural areas can change abiotic factors, providing artificial sources of humidity in summer and decreasing variation of temperatures in winter. Our study aimed at document risk factors of infection in mammal reservoirs of pathogenic Leptospira in the human/wildlife interface of a large metropolitan area. We hypothesize that survival of Leptospira and thus their prevalence in animal reservoirs should be higher in residential areas than in natural habitats, especially after the hot, dry Mediterranean summers. We established the prevalence of Leptospira spp. and identified the serovars in 353 urine samples from micromammals (chiefly the wood mouse Apodemus sylvaticus, n = 266) using direct immunofluorescence and PCR. Animals were captured in spring and autumn, 2011-2012, in two natural parks and two adjacent residential areas in periurban Barcelona (NE Spain). Overall observed prevalence of infection was 11%, ranking between 8% and 13% in the better represented host species. We observed marked differences between seasons; the probability of finding a micromammal infected in spring was three times greater than in autumn (almost four times for wood mouse). Prevalence was not related with type of habitat, micromammal relative abundance or sex of the animal. Three Leptospira species were confirmed: Leptospira interrogans (47% of cases), Leptospira borgpetersenii (41%) and Leptospira kirschneri (12%). The serovars most commonly detected were those typically hosted by rodents, and serovars Ballum and Icterohemorrhagiae were the only ones found in autumn. People living in periurban Barcelona and those visiting the natural areas of the metropolitan area face hazard of infection with rodent-borne Leptospira, especially during spring.

Drivers of Bartonella infection in micromammals and their fleas in a Mediterranean peri-urban area

People living at the human/wildlife interface are at risk of becoming infected with Bartonella for which micromammals act as reservoir. We aimed to determine the factors related to the prevalence of Bartonella and its haplotype diversity in micromammals and in their fleas in a Mediterranean peri-urban environment. We analyzed 511 micromammals, chiefly 407 wood mice (Apodemus sylvaticus), captured into Barcelona metropolitan area (Spain) in spring and autumn from 2011 to 2013 in two natural and two adjacent residential areas, their fleas (grouped in 218 monospecific pools) and 29 fetuses from six Bartonella-positive female wood mice. Amplification of a fragment of ITS was carried out by real time PCR. Prevalence was 49% (57% in the dominant species, the wood mouse), and 12 haplotypes were detected. In general, prevalence was higher in those hosts more heavily infested by fleas, coincident with higher rates of capture, in autumn than in spring, and in adults than in juveniles. Prevalence did not differ between natural and residential areas except for one prevalent haplotype, which was more frequent in natural areas. Prevalence in flea pools (58%) was only explained by Bartonella occurrence in the pool host. In 56.4% of the flea pools with identified Bartonella haplotypes, we found the same haplotype in the host and in its flea pool. Prevalence in wood mouse fetuses was 69%, with at least one infected fetus in all litters, and two litters with all the fetuses infected. indicating that vertical transmission might be important in Bartonella epidemiology in the wood mouse. There is a hazard of Bartonella infection for people living in residential areas and those visiting peri-urban natural areas in Barcelona.