Helminth species diversity of mammals: parasite species richness is a host species attribute

Large-herbivore nemabiomes: patterns of parasite diversity and sharing

Amidst global shifts in the distribution and abundance of wildlife and livestock, we have only a rudimentary understanding of ungulate parasite communities and parasite-sharing patterns. We used qPCR and DNA metabarcoding of fecal samples to characterize gastrointestinal nematode (Strongylida) community composition and sharing among 17 sympatric species of wild and domestic large mammalian herbivore in central Kenya. We tested a suite of hypothesis-driven predictions about the role of host traits and phylogenetic relatedness in describing parasite infections. Host species identity explained 27-53% of individual variation in parasite prevalence, richness, community composition and phylogenetic diversity. Host and parasite phylogenies were congruent, host gut morphology predicted parasite community composition and prevalence, and hosts with low evolutionary distinctiveness were centrally positioned in the parasite-sharing network. We found no evidence that host body size, social-group size or feeding height were correlated with parasite composition. Our results highlight the interwoven evolutionary and ecological histories of large herbivores and their gastrointestinal nematodes and suggest that host identity, phylogeny and gut architecture-a phylogenetically conserved trait related to parasite habitat-are the overriding influences on parasite communities. These findings have implications for wildlife management and conservation as wild herbivores are increasingly replaced by livestock.

Survey on helminths and protozoa of free-living Neotropical bats from Northeastern Brazil

Bats are considered important reservoirs of pathogens of veterinary and medical relevance worldwide. However, despite the increasing attention paid towards the central role of bats in the spreading of some zoonotic infections, studies on their own parasites remain patchy especially in Neotropical regions. Understanding the relationships occurring between bats and their pathogens is a crucial step to determine the implications undermining the ecology and biology of these animals. The present study aims to assess the endoparasitic fauna of Neotropical bats from Northeastern Brazil, with a particular focus on helminths and protozoa. From October 2016 to March 2017, 54 fresh faecal samples were collected in stable shelters inhabited by three different bat species (i.e., Molossus molossus, Myotis lavali and Noctilio albiventris). Samples were analysed using four different techniques (i.e., Centrifugal Sedimentation, Flotation Technique, Spontaneous Sedimentation Technique and FLOTAC^®). A total of 96.29% (52/54) samples were positive for at least one gastrointestinal parasite and 11 different families were identified. In particular, 63.6% (7/11) of the families were of helminths and 36.4% (4/11) of protozoa. Helminths were classified into two different classes (Nematoda and Cestoda) and seven families, whereas the four protozoa classes detected (i.e., Coccidia, Gregarinomorphe, Lobosea and Zoomastigophora) into four families. Eggs of Ancylostomatidae and Hymenolepididae were the most abundan. The findings of this present study demonstrate that Neotropical bats from Northeastern Brazil are parasitized by a wide number of parasites, and some of them may have important implications for Public Health.

Helminth Diversity in Synanthropic Rodents from an Urban Ecosystem

Richness and diversity of parasites depend on a set of interrelated factors related to the characteristics of the host, the environment and the parasites itself. In the City of Buenos Aires, rodent communities vary according to landscape structure. The goal of this paper was to study the variations of helminth richness and diversity among invasive rodent species in different landscape units of the City of Buenos Aires. 73% of the rodents were parasitized with at least one of the 10 identified helminth species. Each rodent species presented its own characteristics in terms of richness, diversity and helminth composition, keeping these characteristics still occupying more than one landscape unit. The infracommunities with greater diversity corresponded to R. norvegicus due to its high values of parasitic richness, proportion of infected hosts and parasite prevalence. Instead, R. rattus and M. musculus infracommunities had lower diversity since a high percentage of them presented a unique helminth species. Within the city, the inhabitants of shantytowns would be the most exposed to zoonotic diseases transmitted by rodents due to high abundance of rodents harboring a high parasite load, including species like Hymenolepis nana and H. diminuta, recognized worldwide from a zoonotic aspect.

Gastrointestinal helminth fauna of rodents from Cambodia: emphasizing the community ecology of host-parasite associations

Extensive field surveys of rodents were conducted in Cambodia from 2008 to 2014 to study the diversity and ecology of helminth infection in wild rodent populations. Gastrointestinal helminths were isolated from 14 species of rodents (569 individuals) trapped from different habitats (forest, dry land, rain-fed land and human settlements) in four provinces of Cambodia (Krong Preah Sihanouk, Mondolkiri, Pursat and Steung Treng). The average prevalence of parasitic infection was 58.5% (range, 16.0-64.7%), and 19 helminth taxa were identified in total. Trichostrongylid nematodes were the most prevalent (25.8%), followed by Raillietina sp. (14.1%), Gongylonema neoplasticum (10.7%), Syphacia muris (9.8%) and Hymenolepis diminuta (9.6%). Potential rodent-borne zoonotic helminths were also identified, and the risks of helminthiasis were discussed. The status of helminth infection and species diversity in rodents from settlements were significantly lower than in rodents from forest and peri-domesticated habitats, which indicates that habitat alteration might affect helminth infection and diversity in rodent hosts. Generalized linear models revealed that host attributes (host species and maturity) and environmental factors (habitat and geographical location) were explanatory variables for helminth infection in these rodents. Using network analyses, we showed that the oriental house rat, Rattus tanezumi, was the most central host in the rodent-helminth assemblage, based on the number of helminth taxa it shared with other rodent species. Therefore, R. tanezumi could play an important role in rodent-helminth interactions and helminth transmission to other rodent hosts.

Helminth fauna of chiropterans in Amazonia: biological interactions between parasite and host

Amazonia, the largest Brazilian biome, is one of the most diverse biomes around the world. Considering the Brazilian chiropteran species, 120 out of known 167 species are registered in Pará state, with 10 endemic species. Despite the high diversity of bats in Amazonia, studies on their parasites, especially on helminths, are scarce. Therefore, the present study aims to study the helminth fauna of different bats from the Pará state, Amazon biome, determine the descriptors of infection, and evaluate the host-parasite interactions, as well as evaluate differences in ecological indexes in accordance with the feeding guilds. The study was developed on 67 bats of 21 species captured in several areas of the Pará state. The animals were identified, divided into feeding guilds, and necropsied. The parasites obtained were identified and quantified. A total of 182 parasites were found in 20.89 % of the studied bats, representing nine species, as follows: Anenterotrema eduardocaballeroi, Anenterotrema liliputianum, Ochoterenatrema caballeroi, Tricholeiperia sp., Parahistiostrongylus octacanthus, Litomosoides guiterasi, Litomosoides brasiliensis, Capillariinae gen. sp., and Hymenolepididae gen. sp. Also, the results indicated that there was no impact of parasitism on host body condition and no relationship between sex and parasite intensity. In relation to the feeding guilds, the omnivores showed higher prevalence and mean intensity. Animals from regions closer to the equator tend to have greater richness in parasite species, but the present study revealed low diversity and richness in species. In conclusion, the ecological pattern observed for other animal groups, in which higher parasitic diversity are registered in lower latitudes, is not applicable to chiropterans from the study area.

The impact of multiple infections on wild animal hosts: a review

Field parasitological studies consistently demonstrate the reality of polyparasitism in natural systems. However, only recently, studies from ecological and evolutionary fields have emphasised a broad spectrum of potential multiple infections-related impacts. The main goal of our review is to reunify the different approaches on the impacts of polyparasitism, not only from laboratory or human medical studies but also from field or theoretical studies. We put forward that ecological and epidemiological determinants to explain the level of polyparasitism, which regularly affects not only host body condition, survival or reproduction but also host metabolism, genetics or immune investment. Despite inherent limitations of all these studies, multiple infections should be considered more systematically in wildlife to better appreciate the importance of parasite diversity in wildlife, cumulative effects of parasitism on the ecology and evolution of their hosts.

Determinants of ectoparasite assemblage structure on rodent hosts from South American marshlands: the effect of host species, locality and season

The relative effects of host species identity, locality and season on ectoparasite assemblages (relative abundances and species richness) harboured by four cricetid rodent hosts (Akodon azarae, Oligoryzomys flavescens, Oxymycterus rufus and Scapteromys aquaticus) were assessed across six closely located sites in Buenos Aires province, Argentina. Relative abundances of ectoparasites (14 species including gamasid mites, an ixodid tick, a trombiculid mite, lice and fleas), as well as total ectoparasite abundance and species richness, were determined mainly by host species and to a lesser extent by locality (despite the small spatial scale of the study), whereas seasonal effect was weak, albeit significant. The abundances of some ectoparasites were determined solely by host, whereas those of other ectoparasites (sometimes belonging to the same higher taxon) were also affected by locality and/or season. In gamasids, there was a significant effect of locality for some species, but not for others. In fleas and lice, the effect of locality was similar in different species, suggesting that this effect is related to the characteristic life history strategy.

Coevolution between multiple helminth infestations and basal immune investment in mammals: cumulative effects of polyparasitism?

Animals often suffer from multiple parasite attacks in natural conditions (i.e., polyparasitism). The community of these parasites, which simultaneously or sequentially infest given host species, has rarely been investigated as a parasitic pressure per se. From this perspective, and despite the impressive number of immunoecological or comparative studies, the impacts of polyparasitism on immune responses are far from being appreciated. Focusing on helminths across a wide range of mammalian species and using a phylogenetic comparative method, we show, for the first time, that an increase in the number of helminth parasite species is positively correlated with an increase in basal immune investment (estimated by the counts of white blood cells) across mammal species. After discussing inherent limits of this comparative approach, we put this result in the evolutionary perspective of multiple parasitic infestations.

Similarity in parasite communities of the teleost fish Pinguipes brasilianus in the southwestern Atlantic: infracommunities as a tool to detect geographical patterns

Patterns of distance decay in similarity among communities of the fish Pinguipes brasilianus (Teleostei: Pinguipedidae) from five areas in the southwestern Atlantic were investigated to determine whether the rate of decay varied depending on the community level or the parasite guild analyzed (ectoparasites, adult endoparasites and larval endoparasites). Similarities in species composition were computed at both the component community and infracommunity levels. Similarity indices were calculated between all possible pairs of assemblages from different zones. Infracommunity similarity values between and within host populations were averaged. Significance of linear regressions for similarity values against distance was assessed using randomization tests. Different patterns were observed for each guild, and similarity among infracommunities within host populations varied accordingly. Decay in similarity over distance was recorded for most communities. The slopes differed significantly between infracommunities and component communities in all cases, and stronger decay was always observed for infracommunities. Different geographical patterns in parasite communities were a consequence of variability in parasite availability in the different regions, modulated by oceanographic conditions, as well as variation among species in terms of host specificity and life-cycles strategies. Infracommunities showed a stronger effect of distance than component communities, probably due to the influence of short term and local variability of oceanographic conditions.