Search Results (198)

Hypothermia-related deaths present significant diagnostic challenges due to non-specific and often inconsistent autopsy findings. This study investigated the histological and immunohistochemical alterations associated with primary and secondary hypothermia in an experimental Rattus norvegicus model, focusing on the effects of benzodiazepine and alcohol ingestion. Twenty-one male rats were divided into three groups: control (K), benzodiazepine-treated (B), and alcohol-treated (A). After two weeks of substance administration, hypothermia was induced and multiple organ samples were analyzed. Histologically, renal tissue showed hydropic and vacuolar degeneration, congestion, and acute tubular injury across all groups, with no significant differences in E-cadherin expression. Lung samples revealed congestion, emphysema, and hemorrhage, with more pronounced vascular congestion in the alcohol and benzodiazepine groups. Cardiac tissue exhibited vacuolar degeneration and protein denaturation, particularly in substance-exposed animals. The spleen showed preserved architecture but increased erythrocyte infiltration and significantly elevated myeloperoxidase (MPO)-positive granulocytes in the intoxicated groups. Liver samples demonstrated congestion, focal necrosis, and subcapsular hemorrhage, especially in the alcohol group. Immunohistochemical analysis revealed statistically significant differences in MPO expression in both lung and spleen tissues, with the highest levels observed in the benzodiazepine group. Similarly, CK7 and CK20 expression in the gastroesophageal junction was significantly elevated in both alcohol- and benzodiazepine-treated animals compared to the controls. In contrast, E-cadherin expression in the kidney did not differ significantly among the groups. These findings suggest that specific histological and immunohistochemical patterns, particularly involving pulmonary, cardiac, hepatic, and splenic tissues, may help differentiate primary hypothermia from substance-related secondary hypothermia. The study underscores the value of integrating toxicological, histological, and molecular analyses to enhance the forensic assessment of hypothermia-related fatalities. Future research should aim to validate these markers in human autopsy series and explore additional molecular indicators to refine diagnostic accuracy in forensic pathology. Full article

Rodents are among the most abundant and ecologically diverse mammals, playing key roles in terrestrial ecosystems and often serving as reservoirs for various zoonotic and wildlife pathogens. Among these are protozoan parasites of the genera Hepatozoon and Theileria, which are known to infect a wide range of domestic and wild animals worldwide. However, little is known about the diversity and phylogenetic relationships of these hemoprotozoans in rodent hosts, particularly in the Arabian Peninsula. The aim of this study was to investigate the presence and genetic diversity of Hepatozoon sp. and Theileria sp. in rodents from different regions of Saudi Arabia and to determine potential reservoir species. A total of 111 rodents were captured and identified by molecular analysis of the mitochondrial 16S rRNA gene. Screening for parasites was performed using PCR amplification of the 18S rRNA gene, followed by sequencing, haplotype analysis, and phylogenetic reconstruction using both maximum likelihood and Bayesian inference methods. Our results represent the first molecular detection of Hepatozoon sp. in Arvicanthis niloticus (31.3%), Gerbillus cheesmani (26.5%), G. nanus (28.5%), and Rattus rattus (32.0%) and of Theileria sp. in G. nanus (21.5%) and R. rattus (24.0%) in Saudi Arabia. Haplotype network analysis revealed seven distinct Hepatozoon haplotypes forming a star-like cluster, suggesting host specificity. One divergent haplotype (Hap_2), 19 mutation steps apart, may represent a novel lineage. Phylogenetic analyses grouped Saudi Hepatozoon sequences with those from reptiles and rodents, forming a clade distinct from sequences isolated from felids and canids. In contrast, Theileria sequences showed low diversity, clustering with a single widespread haplotype found in rodents and ruminants in several regions. These findings significantly expand the current knowledge on rodent-associated apicomplexan parasites in Saudi Arabia, revealing novel Hepatozoon haplotypes and highlighting the role of rodents in the transmission of reptile-associated Hepatozoon spp. This study provides basic molecular data crucial to understanding host–parasite relationships and the potential public and veterinary health implications of these parasites in arid ecosystems. Full article

The Galápagos Petrel (Pterodroma phaeopygia) is a long-lived Critically Endangered seabird endemic to the Galápagos Islands and faces severe threats from invasive species, particularly rodents. Until now, evidence of rat predation on Galápagos Petrel nestlings has been largely indirect, inferred from indirect evidence and predator control outcomes. Here, we present the first photographic documentation of a presumed black rat (Rattus rattus) preying on a Galápagos Petrel nestling, captured by a camera trap on private farmland on Santa Cruz Island. The predation event occurred during a period of parental absence, when the nestling was left unattended while adults foraged at sea. Notably, the parent Petrels continued returning to the nest for 91 days following nestling loss, suggesting strong nest fidelity and highlighting potential energetic costs associated with breeding failure. Our findings reveal critical vulnerabilities during the nestling-rearing phase and emphasize the urgent need to enhance rodent control efforts and protect nesting areas, particularly on farmland outside the Galápagos National Park boundaries. We conclude by providing targeted conservation recommendations to mitigate invasive predator impacts and improve breeding success for this emblematic and imperiled seabird. Full article

Rodents are recognized as reservoirs of a wide range of pathogens, including microsporidia. The presence of microsporidia in the environment of mainland Spain and its islands has become increasingly known, as the number of studies has multiplied over time. The present study was conducted to determine the occurrence and diversity of microsporidia in three rodent species (Mus musculus, Rattus norvegicus, and Rattus rattus) in the Canary Islands, Spain. Ninety-three fecal samples were obtained from wild rodents on La Gomera and Gran Canaria Islands. Each sample was tested using Weber’s modified trichrome staining and immunofluorescence antibody tests (IFATs) against the Encephalitozoon genus and Enterocytozoon bieneusi. The microscopy-positive samples were subsequently analyzed using a nested polymerase chain reaction (PCR) followed by Sanger sequencing. The staining technique showed 38.7% (36/93) positivity, whereas the IFATs for Encephalitozoon spp. and Ent. bieneusi revealed 3.2% (3/93) and 6.5% (6/93) positivity, respectively. Finally, the nested PCR and nucleotide sequence analysis confirmed a 9.7% (9/93) occurrence of Ent. bieneusi and 17.2% occurrence (16/93) of different undetermined microsporidia species, whereas no Encephalitozoon spp. were detected. Seven different Ent. bieneusi genotypes were detected as follows: three known (AAE1, D, and SBM1) and four novel (GRE1, GRE2, LGE1, and LGE2), all of which belonged to Group 1. The results demonstrate, for the first time, that microsporidia are present in the rodent populations of the Canary Islands. Further studies are needed to determine the impact of the presence of microsporidia in rodents on the zoonotic transmission of these parasites. Full article

In addition to natural electromagnetic fields (EMFs), so-called artificial electromagnetic fields exist in the biosphere, with mobile communications being one of their main sources. This study aimed to determine the impact of EMF at a frequency of 1800 MHz on the concentrations of selected hormones, sperm motility, viability, morphology and behaviors in laboratory rats. We used 28 rats divided into two equinumerous groups: control (n = 14) and experimental (n = 14). The rats in the experimental group were exposed to EMF for 12 weeks (for 10 min, four times daily); at the same time, the control specimens were kept in standard conditions. After 12 weeks, half of each group was killed, while the other half was maintained for another 4 weeks with no EMF emission. Elevated corticosterone levels and decreased thyroid-stimulating hormone levels were observed in the experimental specimens, which persisted for 2 weeks after the cessation of EMF emission. Exposure to EMF also resulted in decreased sperm motility and viability, as well as increased rat anxiety. This study shows that exposure to EMF (1800 MHz) may affect the endocrine status of the body and the behavior and reproductive functions of animals. However, hormonal disorders appear to be reversible. Full article

Rodent-borne diseases threaten global public health, impacting the urban poor. Despite widespread application of rodenticide in rodent/rodent-borne disease control programs, empirical evidence demonstrating their effectiveness is lacking. This review proposed guidelines for designing and implementing empirical studies on rodenticides as public health measures. The recommendations include: (i) the importance of the type of quasi-experimental design adopted, and how it creates robust evidence; (ii) how urban slums present both challenges for control and ideal settings for studies; (iii) partnering with pest control authorities and community engagement for long-term viability; (iv) leveraging zoonotic systems with direct/environmental transmission, reliable diagnosis, and high prevalence for effectivity assessment; (v) pairing human cohort studies to observe epidemiological links; (vi) systematic data collection and management protocols; (vii) short- and long-term goals for critical evaluation and course-correction; (viii) focus on mechanistic approach; (ix) the need for standardized reporting of the findings. Full article

Encephalomyocarditis virus (EMCV) causes sporadic and epizootic outbreaks among various domesticated and non-domesticated animal species worldwide. Although outbreaks are mostly reported in domestic pigs, mortality is reported in elephants, ungulates, nonhuman primates (NHPs), and rodents. Rats of the genus Rattus serve as primary reservoirs and vectors, but alternative infection routes have been proposed. Clinical disease is characterized by acute heart failure in most taxonomic groups, often culminating in rapid death. Due to the rapid progression of the disease, diagnostic confirmation is most commonly obtained postmortem. Pathological examination reveals interstitial lymphohistiocytic myocarditis and multiorgan congestion in most cases. EMCV is often demonstrated with RT-PCR or virus isolation techniques, but other methods, e.g., serology and immunohistochemistry, are available. The rapid progression of EMCV precludes effective therapeutic intervention, though agents such as interferon, verapamil, and curcumol have shown potential efficacy. Preventative strategies are crucial, emphasizing biosecurity measures to mitigate rodent contamination of feed and water. Inactivated vaccines have demonstrated protective efficacy in experimental models involving mice, pigs, and elephants, with analogous immunogenic responses observed in various zoological species. Live attenuated vaccines have conferred protection in pigs and NHPs, albeit with variable seroconversion rates in different species. Full article

The introduction of alien species may pose an enormous threat to indigenous flora and fauna. Among introduced animals, probably the most destructive to the natural environment are mammals. This is true at least in regard to the Afrotropical Region (sub-Saharan Africa). This review attempts to summarize our knowledge on alien mammals in this region and their impact on indigenous vertebrate fauna. This review includes 56 mammal species, belonging to 20 families, introduced to sub-Saharan Africa over the last 2000 years. Most are representatives of the following orders: Artiodactyla, Carnivora, and Primates. Most species introduced to sub-Saharan Africa originated from the Oriental (n = 20) and Palearctic (n = 19) regions. Two species, Mus musculus and Rattus rattus, were introduced before 1400 (probably as early as 800 AD), while three others were introduced between 1401 and 1700. The first half of the 17th century saw the highest number (n = 10) of introduced species. Between 1651 and 1850, only two species were introduced; in the following 175 years (1851–2025), as many as 24 species were introduced. Ten of the introduced mammal species, namely Sus scrofa, Capra hircus, Rattus rattus, R. norvegicus, Mus musculus, Felis catus, Canis familiaris, Viverricula indica, Urva auropunctata, and Maccaca fuscicularis, have become invasive species. A total of 39 mammal species were relocated (mainly for hunting purposes) within sub-Saharan Africa. Most of them were representatives of the family Bovidae (76.9%). Relocations are not considered introductions. Based on published records of the impacts of alien mammals on the vertebrate fauna of sub-Saharan Africa, the following mechanisms may be distinguished: predation, competition, hybridization, transmission of diseases and parasites, and habitat destruction (grazing, herbivory, browsing). Most vertebrate species (79.4%) were affected through direct predation, predation and habitat destruction (7.1%), or predation and competition (1.4%). Alien mammals have caused habitat destruction for only 10 species (7.1%). Other effects (competition and genetic pollution) were marginal (3.5%). At least 144 vertebrate species, representing 52 families, have been affected by alien mammals in sub-Saharan Africa: 3 amphibians, 23 reptiles, 89 birds, and 29 mammals. As a result of mammal introductions, 65 species in sub-Saharan Africa have become globally extinct, 45 are considered threatened (listed in the RDB), and 31 other species are in decline, although not included in the RDB. Most extinct birds were affected by introduced rats, mice, feral cats, and dogs. In continental Africa, only seven vertebrate species have been negatively affected by alien mammals. All other affected vertebrates occur on islands. An especially high rate of extinction has been recorded in the Mascarene Islands. In comparison with alien birds in sub-Saharan Africa, the number of introduced mammal species is much lower, but their negative impact on vertebrate fauna is significantly greater. Full article

Leptospirosis is a bacterial zoonosis caused by pathogenic species from the genus Leptospira. Infection mostly occurs through indirect contact with environmental water contaminated with the urine of reservoir animals. Information on the circulation of leptospirosis in West Africa, as well as its potential reservoir hosts, is limited. Therefore, we carried out trapping surveys in the Guinean forest in November 2022, and samples were collected from 42 micromammals. The animals were both morphologically and genetically identified. The lungs and kidneys were screened for Leptospira using Lfb1-gene-targeting real-time PCR, and positive samples were genotyped based on the polymorphic Lfb1 gene. Leptospira species were detected in the kidneys of three micromammals: Mastomys natalensis, Lophuromys sikapusi, and Rattus rattus. Leptospira borgpetersenii was identified in Rattus rattus and Mastomys natalensis that were captured in two different villages. The phylogenetic analysis indicated that this subspecies had previously been detected in one patient in Mayotte, but the reservoir was not identified. A new subspecies of Leptospira kirschneri was isolated in Lophuromys sikapusi from the same village as the Mastomys natalensis positive for L. borgpetersenii. The high diversity of both the reservoirs and Leptospira species in the Guinean forest indicates that we should study other natural regions and reinforce communities’ awareness of Leptospira infection risks in Guinea. Full article

Although the SARS-CoV-2 pandemic primarily affected the human population, the virus has also been detected in various animal species worldwide, raising concerns about its potential to establish new animal reservoirs. This study aimed to investigate the presence of SARS-CoV-2 in non-human primates (NHPs) and synanthropic small mammals (SSMs) in the Jequitinhonha Valley and Northern Minas Gerais, Brazil. Between October 2021 and October 2023, 119 animals were sampled, 82 NHPs and 37 SSMs, across 22 municipalities. A total of 342 biological samples—including oral and nasal swabs, lungs, livers, spleens, blood, and feces—were collected and analyzed using RT-qPCR, while 37 serum samples were submitted to neutralization tests. Despite the diversity of sampled species, habitats, and biological materials, no evidence of SARS-CoV-2 infection or specific antibodies was detected in any of the individuals tested. The results suggest that NHPs and SSMs in these regions did not act as reservoirs for SARS-CoV-2 during the study period. This finding is particularly relevant given the high synanthropy of species such as Callithrix penicillata (black-tufted marmoset) and Rattus rattus (black rat), which frequently interact with human populations. Our study underscores the importance of integrating animal, human, and environmental health perspectives under a One Health framework to monitor emerging zoonotic threats. By providing baseline data on SARS-CoV-2 dynamics in wildlife, we emphasize the need for ongoing ecological and epidemiological surveillance to assess potential spillover events and their implications for biodiversity and public health in Brazil. Full article

Rattus norvegicus (brown rat), a widely distributed rodent and common biomedical model, is a known reservoir for many zoonotic pathogens but has not been traditionally recognized as a host for influenza A virus (IAV). To evaluate their susceptibility, we intranasally inoculated Sprague-Dawley rats with various IAV subtypes, including H5Nx, H7N9, H9N2, H10N8 and the 2009 pandemic H1N1. All strains productively infected the rats, inducing seroconversion without overt clinical signs. While replication efficiency varied, all viruses caused significant lung injury with a preferential tropism for the upper respiratory tract. Investigation of receptor distribution revealed a predominance of α2,3-linked sialic acid (SA) in the nasal turbinates and trachea, whereas α2,6-linked SA was more abundant in the lungs. Notably, both receptor types coexisted throughout the respiratory tract, aligning with the observed tissue-specific replication patterns and broad viral infectivity. These findings demonstrate that rats are permissive hosts for multiple IAV subtypes, challenging their exclusion from IAV ecology. The asymptomatic yet pathogenic nature of infection, combined with the global synanthropy of rats, underscores their potential role as cryptic reservoirs in viral maintenance and transmission. This study highlights the need for expanded surveillance of rodents in influenza ecology to mitigate zoonotic risks. Full article

To investigate the distribution of hantavirus (HV) in rodent organs, we selected eight counties across four regions in Hebei Province (southern, northern, eastern, and central) as study areas. Rodents were captured using night trapping methods, and organ samples were aseptically collected for HV detection via quantitative real-time PCR (qPCR) and gene sequencing. During the 2022–2023 spring and autumn seasons, 1386 rodents were trapped, including 73 Rattus norvegicus carrying Seoul virus (SEOV). The highest detection rate was observed in the liver (3.84%), followed by the kidneys (3.46%) and lungs (3.09%). Viral load analysis revealed higher SEOV RNA levels in the liver than in the lungs and kidneys. Antibody levels in R. norvegicus may influence the detection of viruses in organs. Phylogenetic analysis indicated that all sequences belonged to the S3 subtype, exhibiting regional aggregation and genetic stability. Our findings emphasize the necessity of multi-organ sampling for comprehensive HV surveillance and epidemic risk assessment. Full article

Ticks and tick-borne diseases constitute a crucial focus for the health of both humans and animals worldwide. Although numerous studies on tick-borne diseases have been conducted in China, reports on tick-borne pathogens in ticks and rodents from the China–Vietnam border are scarce. In this study, we investigated tick-borne bacterial pathogens, including Rickettsia, Anaplasmataceae, and Borrelia, in nine rodents (Rattus norvegicus) and 88 ticks collected from cattle and rodents in Jingxi, a city at the China–Vietnam border. Through molecular detection and sequence analysis, four known tick-borne pathogens were identified. Specifically, Rickettsia japonica was detected in 46.3% (37/80) of Haemaphysalis cornigera; Anaplasma phagocytophilum and Candidatus Neoehrlichia mikurensis were identified in one Ixodes granulatus and one rodent, respectively; and Borrelia valaisiana was detected in two I. granulatus. Additionally, a potentially novel species of Rickettsia, provisionally named Rickettsia sp. JX, was detected in 41.3% (33/80) of Ha. cornigera, one Rhipicephalus microplus, three I. granulatus, and nine rodents, whereas a potentially novel species of Borrelia, tentatively named Borrelia sp. JX, was detected in one I. granulatus. To the best of our knowledge, this is the first report on tick-borne bacterial pathogens in ticks and rodents from the China–Vietnam border. These results expand the knowledge of the geographical distribution and vector diversity of tick-borne bacterial pathogens in China and are conducive to the evaluation of thee potential public health risk. Full article

Commonly in seasonal breeding animals, testicular development is inhibited prior to Sertoli cell maturation when environmental conditions become unfavorable, with recovery occurring once conditions improve. However, the precise molecular mechanisms governing this process remain unclear. We investigated the role of androgen receptor (AR) in the seasonal regulation of testicular development in a wild population of Rattus norvegicus caraco, a subspecies of brown rats in Northeast China residing in high-latitude regions, known for its seasonal reproductive patterns. Our results revealed a significant increase in Ar mRNA expression in wild rats with small testes less than 0.2 g and body weights ranging between 80 and 100 g during the nonbreeding season. Further examinations of Ar expression in the testicular development of R. n. caraco in the laboratory under different day lengths and temperatures that simulating breeding and nonbreeding seasons suggest that the maturation of Sertoli cells depends on the upregulation of Ar expression around a testis weight of 0.07–0.18 g, regardless of age and conditions, synchronously accompanying the initiation of the meiotic phase. When Ar expression was suppressed, testicular development was impeded around the stage of Sertoli cell maturation, resulting in decreased spermatogenesis and hindered growth in testis weight. Our findings elucidate how animals control the seasonal inhibition and subsequent recovery of testicular development by regulating Ar expression in R. n. caraco. Full article

Synanthropic rodents are involved in the transmission of several parasitic zoonoses to humans, such as helminth parasites. As part of a multidisciplinary study concerning the rodent population in Barcelona (Spain), 300 specimens of the Norway rat, Rattus norvegicus, were analyzed to elucidate their helminth community, mainly species with a zoonotic potential. The sample included 263 specimens from the sewage system and 37 from public gardens. A total of 253 (84.3%) rats were found to be parasitized, and 206 (68.7%) harbored zoonotic species. Adult rats were found to be more heavily parasitized with zoonotic helminths than juveniles, but the sex and site of capture had no influence. Six zoonotic helminths were identified: Hydatigera taeniaeformis larvae (1.7%), Rodentolepis nana (8.0%), Hymenolepis diminuta (21.3%), Calodium hepaticum (46.3%), Gongylonema neoplasticum (36.7%), and Moniliformis moniliformis (2.3%). Human zoonotic helminth infections often go unreported, so that the role of R. norvegicus in their transmission is unknown. According to our results, it is advisable to monitor and control rodent populations in deprived settlements close to cities and in cities themselves, and to promote good hygienic and sanitary practices, especially among vulnerable populations and workers with high exposure such as sewage workers. Full article