Explore the vast range of titles available.

Most small rodent populations in the world have fascinating population dynamics. In the northern hemisphere, voles and lemmings tend to show population cycles with regular fluctuations in numbers. In the southern hemisphere, small rodents tend to have large amplitude outbreaks with less regular intervals. In the light of vast research and debate over almost a century, we here discuss the driving forces of these different rodent population dynamics. We highlight ten questions directly related to the various characteristics of relevant populations and ecosystems that still need to be answered. This overview is not intended as a complete list of questions but rather focuses on the most important issues that are essential for understanding the generality of small rodent population dynamics.

Scientific background This study employed hematoxylin and eosin (HE) staining to evaluate ovarian developmental status under different photoperiods, including quantification of follicles at various developmental stages and the number and thickness of granulosa cell layer, thereby elucidating the effects of photoperiod on follicle development. Subsequently, enzyme-linked immunosorbent assay (ELISA) was used to measure serum FSH and fecal E2 concentrations, while real-time quantitative PCR was performed to determine mRNA levels of CCND1 and CCND2. Correlation analyses between these markers and follicle counts were conducted to identify key factors involved in follicle development. Furthermore, both real-time quantitative PCR and Western blotting were utilized to investigate the expression of transcription factors FOXO1, FOXL2, and NR5A2 in the ovary at the mRNA and protein levels, respectively, and their relationships with follicle numbers were analyzed, to reveal the potential molecular pathways through which photoperiod regulates follicle development in the striped hamster. The results demonstrate that LP enhances the synthesis of FSH, promotes granulosa cell proliferation, and stimulates follicle development, whereas SP exerts an opposing effect in the striped hamster. FSH is a key hormone involved in follicle development regulated by photoperiods, and CCND2 influences follicle development by modulating granulosa cell proliferation. Additionally, photoperiod alters the expression levels of transcription factors FOXO1, FOXL2, and NR5A2. Correlation analyses revealed that serum FSH concentration was significantly positively correlated with the expression levels of FOXO1 and FOXL2. In turn, the expression of FOXO1 and FOXL2 was significantly positively associated with that of NR5A2, which also showed a significant positive correlation with CCND2 expression. These results suggest a potential regulatory pathway-FSH-FOX-NR5A2-CCND2-involved in photoperiod-dependent follicle development in the striped hamster. The FSH-FOX-NR5A2-CCND2 pathway represents a potential molecular mechanism by which photoperiod regulates follicle development, supported by robust correlative evidence in the striped hamster. The transcription factors FOXO1, FOXL2, and NR5A2 are identified as candidate targets of reproductive activity, with NR5A2 showing a stronger correlation than FOXO1 and FOXL2, thus providing a theoretical foundation for the rational control of rodent population dynamics.

Norway and black rats (Rattus norvegicus and Rattus rattus) are among the most ubiquitous urban wildlife species and are the source of a number of zoonotic diseases responsible for significant human morbidity and mortality in cities around the world. Rodent ecology is a primary determinant of the dynamics of zoonotic pathogens in rodent populations and the risk of pathogen transmission to people, yet many studies of rat-associated zoonoses do not account for the ecological characteristics of urban rat populations. This hinders the development of an in-depth understanding of the ecology of rat-associated zoonoses, limits comparability among studies, and can lead to erroneous conclusions. We conducted a year-long trapping-removal study to describe the ecological characteristics of urban rat populations in an inner-city neighborhood of Vancouver, Canada. The study focused on factors that might influence the ecology of zoonotic pathogens in these populations and/or our understanding of that ecology. We found that rat population density varied remarkably over short geographical distances, which could explain observed spatial distributions of rat-associated zoonoses and have implications for sampling and data analysis during research and surveillance. Season appeared to influence rat population composition even within the urban environment, which could cause temporal variation in pathogen prevalence. Body mass and bite wounds, which are often used in epidemiologic analyses as simple proxies for age and aggression, were shown to be more complex than previously thought. Finally, we found that factors associated with trapping can determine the size and composition of sampled rat population, and thus influence inferences made about the source population. These findings may help guide future studies of rats and rat-associated zoonoses.

Although leptospirosis is traditionally considered a disease of rural, agricultural and flooded environments, Leptospira spp. are found in a range of habitats and infect numerous host species, with rodents among the most significant reservoirs and vectors. To explore the local ecology of Leptospira spp. in a city experiencing rapid urbanization, we assessed Leptospira prevalence in rodents from three locations in Malaysian Borneo with differing levels of anthropogenic influence: 1) high but stable influence (urban); 2) moderate yet increasing (developing); and 3) low (rural). A total of 116 urban, 122 developing and 78 rural rodents were sampled, with the majority of individuals assigned to either the Rattus rattus lineage R3 (n = 165) or Sundamys muelleri (n = 100). Leptospira spp. DNA was detected in 31.6% of all rodents, with more urban rodents positive (44.8%), than developing (32.0%) or rural rodents (28.1%), and these differences were statistically significant. The majority of positive samples were identified by sequence comparison to belong to known human pathogens L. interrogans (n = 57) and L. borgpetersenii (n = 38). Statistical analyses revealed that both Leptospira species occurred more commonly at sites with higher anthropogenic influence, particularly those with a combination of commercial and residential activity, while L. interrogans infection was also associated with low forest cover, and L. borgpetersenii was more likely to be identified at sites without natural bodies of water. This study suggests that some features associated with urbanization may promote the circulation of Leptospira spp., resulting in a potential public health risk in cities that may be substantially underestimated.

The use of rodenticides is a primary method for eradicating rodents from islands for conservation purposes. Rodenticide residue monitoring is often incorporated into rodent eradication project planning to understand the potential effects on nontarget species, but robust long-term sampling is often challenging due to logistical and financial constraints. We documented more than two years of rodenticide residues at fine-scale intervals with over 570 samples associated with a rodent eradication attempt. Brodifacoum-25D Conservation was applied in an attempt to eradicate house mice ( Mus musculus ) from Midway Atoll National Wildlife Refuge in the Northwestern Hawaiian Islands. As a cooperating agency, USDA National Wildlife Research Center collected and tested environmental samples for brodifacoum residues, targeting compartments (invertebrates, vertebrates, water, soil, and plants) that may affect the health of humans and wildlife. Brodifacoum residues in invertebrates peaked immediately after bait application and persisted in low levels until becoming undetectable nine months after bait application. Brodifacoum residues decreased over time but persisted in some vertebrate species (geckos, fish, birds) throughout the one-year sampling period after bait applications. All soil and water environmental samples had either no detectable residues or were under method limit of quantitation. No detectable residues were found in drinking water systems or food plant samples. The adaptive environmental monitoring, which included rapid turnaround of analytical chemistry results, enabled real-time management decisions for nontarget species, mitigation approaches, and community action.

Trypanosoma cruzi, the causative agent of Chagas disease, has been detected in mammalian hosts occupying densely populated urban environments. This suggests that the risk of transmission to humans is higher than prevailing estimates, which largely reflect conditions in rural and peri-urban areas. Understanding the risks posed by T. cruzi thus requires further study of transmission pathways in part because triatomines - the primary vectors for T. cruzi - appear to be uncommon or absent in urban landscapes. Here we test the hypothesis that vertical transmission contributes to the prevalence of infection and diversity of T. cruzi in urban reservoirs. We assessed whether embryos of T. cruzi-positive parous female rodents also exhibit evidence of infection. A diagnostic PCR assay detected T. cruzi in 15 out of 66 (22.7%) embryos from Norway rats, black rats, and house mice captured in New Orleans (LA, USA). Genotyping PCR identified the presence of TcI and non-TcI discrete typing units (DTUs) in individual infected embryos, providing evidence of mixed infection. Next-generation sequencing provided additional evidence of mixed infection in individual embryos. Our findings provide additional evidence that vertical transmission can occur in natural populations of reservoir species and demonstrates for the first time that multiple DTUs can transmit from mother to offspring. Our study also demonstrates that vertical transmission can contribute to the prevalence of infection and diversity of T. cruzi in multiple reservoir species occupying urban landscapes where vectors appear to be rare or absent, providing a new baseline for understanding transmission pathways and eco-epidemiological cycling of T.cruzi.

We report serological surveillance for exposure to SARS-CoV-2 in 1,237 wild rodents and other small mammals across Europe. All samples were negative with the possible exception of one. Given the ongoing circulation of this virus in humans and potential host jumps, we suggest such surveillance be continued.

Effective management of rodent pests necessitates efficient population surveillance. Many of the available methods currently used for estimating rodent populations are either costly or time‐intensive. Rodent trapping demands significant resources, while tracking plates (TP) require high technical expertise and weeks to months of dedicated effort to satisfactorily interpret the plates. Here, we propose integrating Machine Learning techniques to evaluate plates with signs of rodent marks and compare their accuracy with that of conventional human‐interpreted plates. We employed the Otsu method to transform plates from RGB color images to grayscale images, highlighting regions of interest. Subsequently, we applied a global threshold to create binary images, assigning values above a globally determined threshold as 1s and others as 0s. The original images were transformed into new versions with 25 small samples, highlighting regions of interest based on the binary images. We used dimensionality reduction methods to identify the fundamental structure of high‐dimensional data and determined the most important patterns of interest on the plates. Among the methods, Principal Component Analysis, Independent Component Analysis, and Legendre Moments methods were used to visualize patterns and conduct exploratory data analysis. The k ‐nearest neighbors, a versatile and intuitive classification method relying on the similarity principle, predicted the feature vector of PCA, ICA, and LM () results. Ultimately, results from PCA and LM compared favorably against the conventional labur‐intensive manual method, thus proffering those in the field of disease ecology a better alternative for conducting timely and cost‐effective rodent surveillance to monitor rodent distribution hotspots during rodent management programs. We propose a novel approach that could significantly enhance the protocols of rodent surveillance programs, particularly in Low‐ and Middle‐Income Countries, where expertise in interpreting TPs may be limited to enhance rodent surveillance evaluation and timely rodent management while contributing to the indirect control of rodent‐borne zoonoses.

Objective: Wild rodents act as important hosts and reservoirs for both zoonotic and non-zoonotic pathogens, playing a key role in maintaining and transmitting infectious agents in nature. Their presence can lead to contamination of food and water sources, affecting both humans and animals. Methods: This study examined 138 dead rodents from six species (Microtus socialis, Rattus norvegicus, Mus musculus, Meriones libycus, Apodemus witherbyi, and Ellobius lutescens) collected from three regions in Iran. Fecal samples were analyzed for Eimeria spp. and Cryptosporidium spp. using potassium dichromate cultivation and sugar flotation for Eimeria, and modified Ziehl-Neelsen staining for Cryptosporidium. Results: The infection rate for Eimeria spp. was 5.79%, and the identified species included E. falciformis, E. papillata, E. miyairii, E. musculoidei, and E. hungaryensis. For Cryptosporidium spp., a 4.34% infection rate was observed. While Eimeria infections were limited to three rodent species, Cryptosporidium was detected in all six. Conclusion: This study presents the first morphological identification of Eimeria species in rodents in Iran, with findings consistent with host-parasite relationships reported globally. Additionally, the widespread presence of Cryptosporidium spp. in multiple rodent species emphasizes the epidemiological importance of these animals as potential reservoirs of zoonotic pathogens. These results contribute to a better understanding of protozoan diversity and distribution in rodent populations of Iran. Keywords: Rodent, Emeria, Cryptosporidium, Iran Amac: Yabani kemirgenler, hem zoonotik hem de zoonotik olmayan patojenler icin onemli konakci ve rezervuarlar olup, dogada enfeksiyoz etkenlerin devamliliginin saglanmasi ve yayilmasinda kilit rol oynamaktadir. Bu canlilarin varligi, hem insan hem de hayvanlar icin gida ve su kaynaklarinin kontaminasyonuna neden olabilmektedir. Yontemler: Bu calismada, Iran'in uc farkli bolgesinden toplanan alti ture ait (Microtus socialis, Rattus norvegicus, Mus musculus, Meriones libycus, Apodemus witherbyi ve Ellobius lutescens) toplam 138 olu kemirgen incelenmistir. Diski ornekleri, Eimeria spp. icin potasyum dikromat inkubasyonu ve seker flotasyon yontemi, Cryptosporidium spp. icin ise modifiye Ziehl-Neelsen boyama yontemi kullanilarak analiz edilmistir. Bulgular: Eimeria spp. enfeksiyon orani %5,79 olarak belirlenmis; tanimlanan turler arasinda E. falciformis, E. papillata, E. miyairii, E. musculoidei ve E. hungaryensis yer almistir. Cryptosporidium spp. icin saptanan enfeksiyon orani ise %4,34'tur. Eimeria enfeksiyonlari yalnizca uc kemirgen turunde gorulurken, Cryptosporidium alti turun tamaminda tespit edilmistir. Sonuc: Bu calisma, Iran'daki kemirgenlerde Eimeria turlerinin ilk morfolojik tanimlamasini sunmakta olup, elde edilen bulgular dunya genelinde bildirilen konak-parazit iliskileri ile uyumludur. Ayrica, Cryptosporidium spp.'nin bircok kemirgen turunde yaygin olarak bulunmasi, bu hayvanlarin zoonotik patojenler icin potansiyel rezervuarlar olarak epidemiyolojik onemini vurgulamaktadir. Elde edilen veriler, Iran'daki kemirgen populasyonlarinda protozoon cesitliligi ve dagiliminin daha iyi anlasilmasina katki saglamaktadir. Anahtar Kelimeler: Kemirgen, Eimeria, Cryptosporidium, Iran