Host Ecology Research Articles

Comparative gut microbiome research through the lens of ecology: theoretical considerations and best practices.

Comparative approaches in animal gut microbiome research have revealed patterns of phylosymbiosis, dietary and physiological convergences, and environment-host interactions. However, most large-scale comparative studies, especially those that are highly cited, have focused on mammals, and efforts to integrate comparative approaches with existing ecological frameworks are lacking. While mammals serve as useful model organisms, developing generalised principles of how animal gut microbiomes are shaped and how these microbiomes interact bidirectionally with host ecology and evolution requires a more complete sampling of the animal kingdom. Here, we provide an overview of what past comparative studies have taught us about the gut microbiome, and how community ecology theory may help resolve certain contradictions in comparative gut microbiome research. We explore whether certain hypotheses are supported across clades, and how the disproportionate focus on mammals has introduced potential bias into gut microbiome theory. We then introduce a methodological solution by which public gut microbiome data of understudied hosts can be compiled and analysed in a comparative context. Our aggregation and analysis of 179 studies shows that generating data sets with rich host diversity is possible with public data and that key gut microbes associated with mammals are widespread across the animal kingdom. We also show the effects that sample size and taxonomic rank have on comparative gut microbiome studies and that results of multivariate analyses can vary significantly with these two parameters. While challenges remain in developing a universal model of the animal gut microbiome, we show that existing ecological frameworks can help bring us one step closer to integrating the gut microbiome into animal ecology and evolution.

Australian vertebrate hosts of Japanese encephalitis virus: a review of the evidence.

Japanese encephalitis virus (JEV) transmission in temperate Australia has underscored a critical need to characterise transmission pathways and identify probable hosts of the virus. This systematic review consolidates existing research on the vertebrate hosts of JEV that are known to exist in Australia. Specifically, we aim to identify probable species involved in JEV transmission, their potential role as hosts and identify critical knowledge gaps. Data were extracted from studies involving experimental infection, seroprevalence and virus isolation and were available for 22 vertebrate species known to reside in Australia. A host competence score was calculated to assess the ability of each species to generate and sustain a viraemia. Based on the host competence score and ecology of each species, we find that ardeid birds, feral pigs and flying foxes have potential as maintenance hosts for JEV in the Australian context. We also note that domestic pigs are frequently infected during outbreaks, but their role as amplification hosts in Australia is unclear. Evidence to confirm these roles is sparse, emphasising the need for further targeted research. This review provides a foundation for future investigations into JEV transmission in Australia, advocating for enhanced surveillance and standardised research methodologies to better understand and mitigate the virus's impact.

Prophages in Vibrio.

Although tailed bacteriophages (phages) of the class Caudoviricetes are thought to constitute the most abundant and ecologically relevant group of phages that can integrate their genome into the host chromosome, it is becoming increasingly clear that other prophages are widespread. Here, we show that prophages derived from filamentous and tailless phages with genome sizes below 16 kb make up the majority of prophages in marine bacteria of the genus Vibrio. To estimate prophage prevalence unaffected by database biases, we combined comparative genomics and chemical induction of 58 diverse Vibrio cyclitrophicus isolates, resulting in 107 well-curated prophages. Complemented with computationally predicted prophages, we obtained 1,158 prophages from 931 naturally co-existing strains of the family Vibrionaceae. Prophages resembling tailless and filamentous phages predominated, accounting for 80% of all prophages in V. cyclitrophicus and 60% across the Vibrionaceae. In our experimental model, prophages of all three viral realms actively replicated upon induction indicating their ability to transfer to new hosts. Indeed, prophages were rapidly gained and lost, as suggested by variable prophage content between closely related V. cyclitrophicus. Prophages related to filamentous and tailless phages were integrated into only three genomic locations and restored the function of their integration site. Despite their small size, they contained highly diverse accessory genes that may contribute to host fitness, such as phage defense systems. We propose that, like their well-studied tailed equivalent, tailless and filamentous temperate phages are active and highly abundant drivers of host ecology and evolution in marine Vibrio, which have been largely overlooked.

How host ecology influences the parasite communities of three Australian flathead fishes, Platycephalus spp. (Scorpaeniformes: Platycephalidae)

This study investigated the role of host traits, habitat, and sampling season on the prevalence and intensity of parasites in three species of platycephalid fishes. Three host species sampled were dusky flathead (Platycephalus fuscus, n = 3), blue-spotted flathead (Platycephalus caeruleopunctatus, n = 38), and tiger flathead (Platycephalus richardsoni, n = 59). A total of 14 metazoan parasite species were collected over 15 months, between July 2020 and September 2021. The parasites found included a chondracanthid copepod, adult hemiuroidean trematodes, cestode plerocercoids, larval and adult acanthocephalans, larval and adult nematodes, and an unknown species of helminth. General linear models were used to assess the relationship between host traits and sampling season with parasite infection intensity. The infection intensity of an unidentified plerocercoid species in P. caeruleopunctatus was found to be significantly associated with both sampling season and the interaction of host mass with sex. In P. richardsoni the infection intensity of the acanthocephalan, Corynosoma sp. was found to correlate with sampling season. The highest richness of parasite taxa was recorded from P. richardsoni, which may be due to the wide depth range of P. richardsoni, coupled with its generalist diet.

Discovery of adults of the gorgoderid trematode Cercaria duplicata with first morphological description, molecular identification and notes on host specificity

Rhopalocercous Cercaria duplicata von Baer, 1827 develops in an intermediate host, the unionid bivalve Anodonta anatina (L.), but its adult form has been unknown. We examined eight fish species occurring in the presence of a highly infested population of A. anatina in the Zesławice reservoir (S Poland). Gravid Phyllodistomum specimens were obtained from the ureters of ide, Leuciscus idus (L.) and common rudd, Scardinius erythrophthalmus (L.). One of the rudd specimens was doubly infected, a trematode was also found in the urinary bladder. In addition, a gravid Phyllodistomum specimen was found in the ureter of a tench Tinca tinca (L.), caught in Lake Ilmėdas (Lithuania). In order to clarify the phylogenetic position of larval and adult gorgoderids and to establish their life cycle, ITS2 and 28S rDNA sequences were analysed. The analysis showed that adult Phyllodistomum specimens located in the ureters are conspecific with C. duplicata. The trematode found in the urinary bladder of S. erythrophthalmus was P. folium (Olfers, 1816). It is suggested that adult stages of C. duplicata should be referred to as Phyllodistomum duplicatum n. comb. The intercaecal position of the uterus and the deeply-lobed ovary are the main features distinguishing it from other Phyllodistomum species. Host specificity and ecology are discussed.

Proximity to humans is associated with antimicrobial-resistant enteric pathogens in wild bird microbiomes

Humans are radically altering global ecology, and one of the most apparent human-induced effects is urbanization, where high-density human habitats disrupt long-established ecotones. Changes to these transitional areas between organisms, especially enhanced contact among humans and wild animals, provide new opportunities for the spread of zoonotic pathogens. This poses a serious threat to global public health, but little is known about how habitat disruption impacts cross-species pathogen spread. Here, we investigated variation in the zoonotic enteric pathogen Campylobacter jejuni. The ubiquity of C.jejuni in wild bird gut microbiomes makes it an ideal organism for understanding how host behavior and ecology influence pathogen transition and spread. We analyzed 700 C.jejuni isolate genomes from 30 bird species in eight countries using a scalable generalized linear model approach. Comparing multiple behavioral and ecological traits showed that proximity to human habitation promotes lineage diversity and is associated with antimicrobial-resistant (AMR) strains in natural populations. Specifically, wild birds from urban areas harbored up to three times more C.jejuni genotypes and AMR genes. This study provides novel methodology and much-needed quantitative evidence linking urbanization to gene pool spread and zoonoses.

Ecology and evolution of avian influenza viruses

Four types of influenza virus have been identified in nature: influenza A, B, and C viruses are capable of infecting humans, and influenzas A and B cause annual epidemics (seasonal flu) in humans; however, influenza D is currently known to infect only pigs and cattle. The influenza A viruses (IAVs) are of greatest importance to humans, causing widespread significant morbidity and mortality, and have been responsible for at least five pandemics documented since the beginning of the 20th century (Table 1). The H1N1 and H3N2 IAVs continue to circulate in humans as seasonal influenza. In addition to humans, IAVs have a wide range of host animal species in nature, especially wild aquatic birds, the reservoir hosts of IAVs. The IAVs isolated from or adapted to an avian host are named avian influenza viruses (AIVs), and are of great concern owing to their involvement in the genesis of pandemic and outbreak strains. Moreover, the majority of AIVs persist in wild birds and domestic poultry, and novel variants continue to emerge in birds and other hosts, posing non-negligible threats to host ecology and public health.

Bacteriophage-driven emergence and expansion of Staphylococcus aureus in rodent populations.

Human activities such as agriculturalization and domestication have led to the emergence of many new pathogens via host-switching events between humans, domesticated and wild animals. Staphylococcus aureus is a multi-host opportunistic pathogen with a global healthcare and economic burden. Recently, it was discovered that laboratory and wild rodents can be colonised and infected with S. aureus, but the origins and zoonotic potential of rodent S. aureus is unknown. In order to trace their evolutionary history, we employed a dataset of 1249 S. aureus genome sequences including 393 of isolates from rodents and other small mammals (including newly determined sequences for 305 isolates from 7 countries). Among laboratory mouse populations, we identified multiple widespread rodent-specific S. aureus clones that likely originated in humans. Phylogeographic analysis of the most common murine lineage CC88 suggests that it emerged in the 1980s in laboratory mouse facilities most likely in North America, from where it spread to institutions around the world, via the distribution of mice for research. In contrast, wild rodents (mice, voles, squirrels) were colonized with a unique complement of S. aureus lineages that are widely disseminated across Europe. In order to investigate the molecular basis for S. aureus adaptation to rodent hosts, genome-wide association analysis was carried out revealing a unique complement of bacteriophages associated with a rodent host ecology. Of note, we identified novel prophages and pathogenicity islands in rodent-derived S. aureus that conferred the potential for coagulation of rodent plasma, a key phenotype of abscess formation and persistence. Our findings highlight the remarkable capacity of S. aureus to expand into new host populations, driven by the acquisition of genes promoting survival in new host-species.

Further evidence of low infection frequencies of Wolbachia in soil arthropod communities

Endosymbiotic Alphaproteobacteria of the genus Wolbachia are exclusively transferred maternally from mother to offspring, but horizontal transfer across species boundaries seems to be frequent as well. However, the (ecological) mechanisms of how these bacteria are transferred between distantly related arthropod hosts remain unclear. Based on the observation that species that are part of the same ecological community often also share similar Wolbachia strains, host ecology has been hypothesized as an important factor enabling transmission and a key factor in explaining the global distribution of Wolbachia lineages.In this study, we focus on the diversity and abundance of Wolbachia strains in soil arthropods, a so far rather neglected community. We screened 82 arthropod morphotypes collected in the beech forest (dominated by Fagus sp.) soil in the area of Göttingen in central Germany for the presence of Wolbachia. By performing a PCR screen with Wolbachia-MLST markers (coxA, dnaA, fbpA, ftsZ, gatB, and hcpA), we found a rather low infection frequency of 12,2%. Additionally, we performed metagenomic screening of pooled individuals from the same sampling site and could not find evidence that this low infection frequency is an artefact due to PCR-primer bias. Phylogenetic analyses of the recovered Wolbachia strains grouped them in three known supergroups (A, B, and E), with the first report of Wolbachia in Protura (Hexapoda). Moreover, Wolbachia sequences from the pseudoscorpion Neobisium carcinoides cluster outside the currently known supergroup diversity. Our screening supports results from previous studies that the prevalence of Wolbachia infections seems to be lower in soil habitats than in above-ground terrestrial habitats. The reasons for this pattern are not completely understood but might stem from the low opportunity of physical contact and the prevalence of supergroups that are less suited for horizontal transfer.

Discovery of a novel spotted fever group Rickettsia, "Candidatus Rickettsia kedanie," in unfed larval chigger mites, Leptotrombidium scutellare.

Spotted fever group (SFG) rickettsia, the causative agent of SFG rickettsiosis, is predominantly carried by ticks, whereas Orientia tsutusgamushi, the causative agent of scrub typhus, is primarily transmitted by chigger mites in Japan. In this study, we attempted to isolate intracellular eubacteria from Leptotrombidium scutellare, a major vector of O. tsutsugamushi; moreover, we isolated an SFG rickettsia using a mosquito-derived cell line. Draft genome sequences of this unique isolate, by applying criteria for species delimitation, classified this isolate as a novel strain, proposed as "Rickettsia kedanie." Further genetic analysis identified conserved virulence factors, and the isolate successfully propagated in mammalian cells, suggesting its ability to cause diseases in humans. The presence of SFG rickettsia in unfed larvae implies potential dual-pathogen carriage and reflects a symbiotic relationship similar to that between the mites and O. tsutsugamushi, indicating possibility of its transovarial transmission from female adults. Furthermore, conserved genomic similarity of the novel isolate to known SFG rickettsia suggests potential multiple hosts, including chiggers and ticks. In the natural environment, ticks, chigger mites, and wild animals may carry new isolates, complicating the infection cycle and increasing the transmission risks to humans. This discovery challenges the conventional association of SFG rickettsia with ticks, emphasizing its implications for research and disease control. However, this study was confined to a particular species of chigger mites and geographic area, underscoring the necessity for additional studies to comprehend the ecological dynamics, host interactions, and health implications linked to this newly identified SFG rickettsia.

Insect-microbe interactions and their influence on organisms and ecosystems.

Microorganisms are important associates of insect and arthropod species. Insect-associated microbes, including bacteria, fungi, and viruses, can drastically impact host physiology, ecology, and fitness, while many microbes still have no known role. Over the past decade, we have increased our knowledge of the taxonomic composition and functional roles of insect-associated microbiomes and viromes. There has been a more recent shift toward examining the complexity of microbial communities, including how they vary in response to different factors (e.g., host genome, microbial strain, environment, and time), and the consequences of this variation for the host and the wider ecological community. We provide an overview of insect-microbe interactions, the variety of associated microbial functions, and the evolutionary ecology of these relationships. We explore the influence of the environment and the interactive effects of insects and their microbiomes across trophic levels. Additionally, we discuss the potential for subsequent synergistic and reciprocal impacts on the associated microbiomes, ecological interactions, and communities. Lastly, we discuss some potential avenues for the future of insect-microbe interactions that include the modification of existing microbial symbionts as well as the construction of synthetic microbial communities.

Using an adaptive modeling framework to identify avian influenza spillover risk at the wild-domestic interface

The wild to domestic bird interface is an important nexus for emergence and transmission of highly pathogenic avian influenza (HPAI) viruses. Although the recent incursion of HPAI H5N1 Clade 2.3.4.4b into North America calls for emergency response and planning given the unprecedented scale, readily available data-driven models are lacking. Here, we provide high resolution spatial and temporal transmission risk models for the contiguous United States. Considering virus host ecology, we included weekly species-level wild waterfowl (Anatidae) abundance and endemic low pathogenic avian influenza virus prevalence metrics in combination with number of poultry farms per commodity type and relative biosecurity risks at two spatial scales: 3 km and county-level. Spillover risk varied across the annual cycle of waterfowl migration and some locations exhibited persistent risk throughout the year given higher poultry production. Validation using wild bird introduction events identified by phylogenetic analysis from 2022 to 2023 HPAI poultry outbreaks indicate strong model performance. The modular nature of our approach lends itself to building upon updated datasets under evolving conditions, testing hypothetical scenarios, or customizing results with proprietary data. This research demonstrates an adaptive approach for developing models to inform preparedness and response as novel outbreaks occur, viruses evolve, and additional data become available.

Testing the radiation cascade in postglacial radiations of whitefish and their parasites: founder events and host ecology drive parasite evolution.

Reciprocal effects of adaptive radiations on the evolution of interspecific interactions, like parasitism, remain barely explored. We test whether the recent radiations of European whitefish (Coregonus spp.) across and within perialpine and subarctic lakes promote its parasite Proteocephalus fallax (Platyhelminthes: Cestoda) to undergo host repertoire expansion via opportunity and ecological fitting, or adaptive radiation by specialization. Using de novo genomic data, we examined P. fallax differentiation across lakes, within lakes across sympatric host species, and the contributions of host genetics versus host habitat use and trophic preferences. Whitefish intralake radiations prompted parasite host repertoire expansion in all lakes, whereas P. fallax differentiation remains incipient among sympatric fish hosts. Whitefish genetic differentiation per se did not explain the genetic differentiation among its parasite populations, ruling out codivergence with the host. Instead, incipient parasite differentiation was driven by whitefish phenotypic radiation in trophic preferences and habitat use in an arena of parasite opportunity and ecological fitting to utilize resources from emerging hosts. Whilst the whitefish radiation provides a substrate for the parasite to differentiate along the same water-depth ecological axis as Coregonus spp., the role of the intermediate hosts in parasite speciation may be overlooked. Parasite multiple-level ecological fitting to both fish and crustacean intermediate hosts resources may be responsible for parasite population substructure in Coregonus spp. We propose parasites' delayed arrival was key to the initial burst of postglacial intralake whitefish diversification, followed by opportunistic tapeworm host repertoire expansion and a delayed nonadaptive radiation cascade of incipient tapeworm differentiation. At the geographical scale, dispersal, founder events, and genetic drift following colonization of spatially heterogeneous landscapes drove strong parasite differentiation. We argue that these microevolutionary processes result in the mirroring of host-parasite phylogenies through phylogenetic tracking at macroevolutionary and geographical scales.

Prevalence and underlying mechanisms of phylosymbiosis in land plants

Abstract Phylosymbiosis, the congruence of microbiome composition with host phylogeny, is a valuable framework for investigating plant–microbe associations and their evolutionary ecology. This review assesses the prevalence of phylosymbiosis across the plant kingdom, elucidates the fundamental ecological and evolutionary processes contributing to its occurrence based on previous research and explores commonly used methods for identifying phylosymbiosis. We find that the presence of phylosymbiosis may be influenced by both phylogenetic distance and the taxonomic level at which host plants are examined, with the strength of associations potentially decreasing as the taxonomic scale becomes finer. Notably, the endophytic microbiome exhibits a stronger phylosymbiosis signal compared with the epiphytic or rhizosphere-associated microbiomes. Microorganisms such as fungi and bacteria can yield highly variable evidence for phylosymbiosis due to differences in colonization, transmission or functional characteristics. We also outline how the four community assembly processes (dispersal, selection, diversification and drift) contribute to the establishment and maintenance of host–microbe phylosymbiosis. Furthermore, we highlight the diversity of methods employed to detect phylosymbiosis, which involves three key processes: constructing host phylogenies, assessing microbial data and statistically evaluating the correlation between host phylogeny and microbial composition. Remarkably different methodologies across studies make comparisons between findings challenging. To advance our understanding, future research is expected to explore phylosymbiosis at lower taxonomic levels and investigate different microbial communities coexisting synergistically within the same host. Understanding the relative importance of community assembly processes in driving phylosymbiosis will be critical for gaining deeper insights into the ecology and evolution of host–microbe interactions.

Environmentally responsive changes in mucus indicators and microbiota of Chinese sturgeon Acipensersinensis

The impact of environmental factors on the health of the endangered Chinese sturgeon (Acipenser sinensis) and the potential hazards associated with sample collection for health monitoring pose urgent need to its conservation. In this study, Chinese sturgeons were selected from indoor and outdoor environments to evaluate metabolic and tissue damage indicators, along with a non-specific immune enzyme in fish mucus. Additionally, the microbiota of both water bodies and fish mucus were determined using 16S rRNA high-throughput sequencing. The correlation between the indicators and the microbiota was investigated, along with the measurement of multiple environmental factors. The results revealed significantly higher levels of two metabolic indicators, total protein (TP) and cortisol (COR) in indoor fish mucus compared to outdoor fish mucus (p < 0.05). The activities of acid phosphatase (ACP), alkaline phosphatase (ALP), creatine kinase (CK), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were significantly higher in indoor fish, serving as indicators of tissue damage (p < 0.05). The activity of lysozyme (LZM) was significantly lower in indoor fish (p < 0.01). Biomarker analysis at the phylum and genus levels in outdoor samples revealed that microorganisms were primarily related to the catabolism of organic nutrients. In indoor environments, microorganisms displayed a broader spectrum of functions, including ecological niche establishment, host colonization, potential pathogenicity, and antagonism of pathogens. KEGG functional enrichment corroborated these findings. Dissolved oxygen (DO), electrical conductivity (EC), ammonia nitrogen (NH3–N), turbidity (TU), and chemical oxygen demand (COD) exerted effects on outdoor microbiota. Temperature (TEMP), nitrate (NO3−), total phosphorus (TP), and total nitrogen (TN) influenced indoor microbiota. Changes in mucus indicators, microbial structure, and function in both environments were highly correlated with these factors. Our study provides novel insights into the health impacts of different environments on Chinese sturgeon using a non-invasive method.

Assessment of the occurrence of the second generation of Mythimna loreyi Duponchel (Lepidoptera: Noctuidae) using temperature-dependent developmental and oviposition models.

A significant crop pest, Mythimna loreyi, migrates annually to Korea and has been frequently observed in rice and corn fields. However, the phenology of this pest, particularly in relation to its ecological interactions and host crop seasons in Korea, remains poorly understood. This study aims to clarify the timing of the second generation of M. loreyi in Korea to enhance pest management strategies. To achieve this, we developed temperature-dependent models for developmental and ovipositional rates, studying these processes across five constant temperatures (15, 20, 25, 30, and 35°C). Our models, which showed a high correlation with observed data (r2 ≥ 0.93), include a theoretical approach that combines the developmental variation of immatures with the necessary degree-days for 50% egg laying and complete egg development. These predictions allow for the forecasting of the second generation's occurrence, with relatively small deviations (one to three days) observed at two different field sites. The insights from this study are critical for both understanding the ecology of M. loreyi and for informing practical management decisions, such as optimal placement of barriers to prevent immigration and strategies for controlling local populations.

Leucocytozoon Infection Does Not Influence the Survival of Boreal Owl Aegolius funereus Nestlings.

Leucocytozoon infection has been observed to impact the reproductive ecology and physiology of avian hosts, but its influence on nestling survival remains unclear. We investigated the effect of Leucocytozoon infection intensity, determined through triplicate PCR sample analyses, on the survival of 256 boreal owl (Aegolius funereus) nestlings during an 8-yr study. Contrary to our expectations, the survival probability of boreal owl nestlings was not influenced by their Leucocytozoon infection intensity. Nestling age and Leucocytozoon infection intensity in male and female parents also did not impact nestling survival. Instead, food abundance and hatching order were the key factors influencing nestling survival. Additionally, we observed a significantly higher Leucocytozoon infection intensity in male parents compared to female parents and nestlings. We suggest a distinct division of parental roles may lead females and nestlings staying within the nest boxes (cavities) to experience lower exposure to potential vectors transmitting blood parasites than their male counterparts. Our study shows that Leucocytozoon disease may not be lethal for boreal owl chicks, exhibiting a below-average infection intensity compared to their male parents.

Occurrence of Free-Living Amoebae in Non-Human Primate Gut.

The gut microbiome reflects health and predicts possible disease in hosts. A holistic view of this community is needed, focusing on identifying species and dissecting how species interact with their host and each other, regardless of whether their presence is beneficial, inconsequential, or detrimental. The distribution of gut-associated eukaryotes within and across non-human primates is likely driven by host behavior and ecology. To ascertain the existence of free-living amoebae (FLA) in the gut of wild and captive non-human primates, 101 stool samples were collected and submitted to culture-dependent microscopy examination and DNA sequencing. Free-living amoebae were detected in 45.4% (46/101) of fecal samples analyzed, and their morphological characteristics matched those of Acanthamoeba spp., Vermamoeba spp., heterolobosean amoeboflagellates and fan-shaped amoebae of the family Vannellidae. Sequence analysis of the PCR products revealed that the suspected amoebae are highly homologous (99% identity and 100% query coverage) with Acanthamoeba T4 genotype and Vermamoeba vermiformis amoebae. The results showed a great diversity of amoebae in the non-human primate's microbiome, which may pose a potential risk to the health of NHPs. To our knowledge, this is the first report of free-living amoebae in non-human primates that are naturally infected. However, it is unknown whether gut-borne amoebae exploit a viable ecological niche or are simply transient residents in the gut.

Mapping of intermediate host snails for schistosomiasis in the Democratic Republic of Congo: a systematic review.

Schistosomiasis is a snail-borne disease that has a considerable impact on human and animal health, particularly in sub-Saharan Africa. The intermediate hosts of the schistosome parasites are freshwater snails of the genera Biomphalaria Preston, 1910 and Bulinus Müller, 1781. In order to identify existing gaps in the spread of the disease in the Democratic Republic of Congo (DRC), this study compiled the available knowledge of the distribution, population dynamics and ecology of the intermediate hosts of schistosomiasis. A systematic literature search was conducted in PubMed, Embase and Scopus for all malacological studies on schistosoma intermediate hosts in DRC published between 1927 and October 2022. A total of 55 records were found, of which 31 met the inclusion criteria: these were published field and experimental studies conducted in the DRC and focused on snails as intermediate hosts of schistosomes. The analysis of these studies revealed that more up-to-date data on the distribution of snail intermediate hosts in the DRC are needed. Moreover, ecological factors have been less studied for Bulinus species than for Biomphalaria species. These factors play a crucial role in determining suitable snail habitats, and the lack of comprehensive information poses a challenge in snail control. This review makes it clear that there are no current malacological data in the DRC. There is a clear need for molecular and ecological research to update the exact species status and population dynamics of all potential intermediate host species. This will facilitate targeted snail control measures that complement drug treatment in the control of schistosomiasis in the country.

The Profound Influence of Gut Microbiome and Extracellular Vesicles on Animal Health and Disease.

The animal gut microbiota, comprising a diverse array of microorganisms, plays a pivotal role in shaping host health and physiology. This review explores the intricate dynamics of the gut microbiome in animals, focusing on its composition, function, and impact on host-microbe interactions. The composition of the intestinal microbiota in animals is influenced by the host ecology, including factors such as temperature, pH, oxygen levels, and nutrient availability, as well as genetic makeup, diet, habitat, stressors, and husbandry practices. Dysbiosis can lead to various gastrointestinal and immune-related issues in animals, impacting overall health and productivity. Extracellular vesicles (EVs), particularly exosomes derived from gut microbiota, play a crucial role in intercellular communication, influencing host health by transporting bioactive molecules across barriers like the intestinal and brain barriers. Dysregulation of the gut-brain axis has implications for various disorders in animals, highlighting the potential role of microbiota-derived EVs in disease progression. Therapeutic approaches to modulate gut microbiota, such as probiotics, prebiotics, microbial transplants, and phage therapy, offer promising strategies for enhancing animal health and performance. Studies investigating the effects of phage therapy on gut microbiota composition have shown promising results, with potential implications for improving animal health and food safety in poultry production systems. Understanding the complex interactions between host ecology, gut microbiota, and EVs provides valuable insights into the mechanisms underlying host-microbe interactions and their impact on animal health and productivity. Further research in this field is essential for developing effective therapeutic interventions and management strategies to promote gut health and overall well-being in animals.