Suncus Murinus Research Articles

Impact of Sanitation on Rodent Pullulation and Plague Status in an Informal Settlement on the Outskirts of Mahajanga (Madagascar)

Plague is a zoonotic disease caused by Yersinia pestis, and it is endemic in Madagascar. The plague cycle involves wild and commensal rodents and their fleas; humans are an accidental host. Madagascar is the country where plague burden is the highest. Plague re-emerged in Mahajanga, the western coast of Madagascar, in the 1990s and infected populations in the popular and insalubrious zones. Sanitation is considered a primary barrier to infection by excluding pathogens from the environment and reservoirs. Poor housing and hygiene and proximity to rodents and fleas in everyday life are major and unchanged risk factors of plague. The aim of this study was to measure the impact of sanitation on Yersinia pestis bacteria in human and small mammal reservoirs and flea vectors. This study was conducted on 282 households within 14 neighborhoods. Two sessions of sampling were conducted in 2013 and 2016. Small mammals were trapped inside and around houses using live traps. Fleas, blood and spleen were sampled to detect Y. pestis infection and antibodies and determine the level of plague circulation before and after the installation of sanitation in order to assess the impact of sanitation improvement on inhabitant health. Two major types of housing can be described, i.e., formal and informal (traditional), scattered in all the suburbs. Among the small mammals captured, 48.5% were Suncus murinus, and 70% of houses were infested. After sanitation, only 30% of houses remained infested, and most of them were located around the market. Fleas were mostly Xenopsylla cheopis. Before and after intervention, the overall prevalence of fleas was the same (index 4.5) across the 14 suburbs. However, the number of houses with fleas drastically decreased, and the flea index increased significantly in rodent-infested houses. Rodent abundance also decreased from 17.4% to 6.1% before and after intervention, respectively. A serology study highlights that plague is still circulating in Mahajanga, suggesting that small mammals maintain enzootic plague transmission in the city.

Abundance and taxonomic characterization of chigger mites (Acari: Trombiculidae and Walchiidae) associated with rodents in selected scrub typhus-prone areas in Southern and Western provinces of Sri Lanka

Larval trombiculid mites (chiggers) are the vectors and reservoirs of the potentially lethal infectious disease, scrub typhus (ST) caused by Orientia tsutsugamushi. Small rodents are natural hosts of parasitic larval stage of the chigger mites. This study focused on determining the abundance of chigger mites associated with rodents in Sri Lanka and the taxonomic characterization of field-caught chiggers. Field sampling was conducted in the districts of Galle, and Hambantota of the Southern Province, and Gampaha of the Western Province, in 2019 and 2020. Sampling sites were selected according to the patient distribution. A total of 58 small mammals (rodent species: Rattus rattus (Black rat), Rattus norvegicus (Brown rat), Tatera indica (Indian gerbil), Gollunda ellioti (Indian bush rat) and Suncus murinus (Asian house shrew)) were captured using baited traps. Chiggers from the captured rodents were speciated morphologically by visual inspection and morphometry using a camera-mounted light microscope (x100). A total of 394 chigger mites were collected. Three different genera were identified, including Leptotrombidium, Schoengastiella, and Microtrombicula. Leptotrombidium imphalum (72.59%; n=286) was the predominant species, followed by Schoengastiella punctata (8.12%; n=32). Some specimens were identifiable only up to genus level, Leptotrombidium sp. (3.55%; n=14) and Microtrombicula sp. (4.82%; n= 19). Some (7.11%; n=28) were not trombiculid mites, while 3.81%; n=15 was damaged beyond identification. Leptotrombidium imphalum was detected for the first time parasitizing the murids - Rattus novergicus and Tatera indica in the district of Galle, a new locality. In addition, S. punctata was recorded in a new locality in the Gampaha district, Western province with a new host association, Golunda ellioti. This study emphasizes the need for further entomological surveys in ST disease-endemic areas. Developing a morphological identification key for chigger mites in Sri Lanka is a top priority to facilitate field surveys.

Action of cocaine- and amphetamine-regulated transcript (CART) peptide to attenuate cisplatin-induced emesis in Suncus murinus (house musk shrew)

Cocaine- and amphetamine-regulated transcript (CART) peptide is a brain-gut neuropeptide that has been implicated in a range of physiological functions including appetite, which is disturbed during chemotherapy. The aims of the present study were to identify the distribution and expression of CART mRNA and CART peptide, and to examine the potential of CART (55-102) to attenuate cisplatin-induced emesis in Suncus murinus. CART mRNA and peptide were detected throughout the entire brain, including the forebrain, hypothalamus, and brainstem, and also in the gut wall and stomach. In conscious, freely moving animals, intracerebroventricular administration of CART (55-102) did not modulate food and water intake or alter locomotor activity when administered alone. Cisplatin induced emesis and upregulated the expression of CART mRNA in the brainstem. However, CART (55-102) reduced the number of cisplatin-induced retches. Both CART (55-102) and cisplatin increased the number of c-Fos positive cells in the nucleus tractus solitarius, lateral hypothalamus, paraventricular hypothalamus, and bed nucleus of the stria terminalis (BNST), compared to saline-treated animals, whereas cisplatin also induced c-Fos expression in the area postrema (AP), arcuate nucleus, and central nucleus of the amygdala. Pre-treatment with CART (55-102) significantly attenuated the increased c-Fos positive cells in the BNST and AP. These data indicate that CART mRNA and peptide were localized to regions involved in reward/ enforcement, emotion, feeding and emesis. The anti-emetic effect of CART (55-102) against cisplatin-induced emesis may involve both the forebrain limbic system and the brainstem.

Genome sequencing projects reveal new insights into the mammalian Gonadotropin-releasing Hormone II system.

The type II gonadotropin-releasing hormone (GnRH-II) was first discovered in chicken (Gallus gallus) brain and then shown to be present in many vertebrates. Indeed, its structure is conserved unchanged throughout vertebrate evolution from teleost fish through to mammals suggesting a crucial function. Yet the functional significance has been largely unexplored. Studies in comparative endocrinology show that the GnRH-II system is differentially functional in mammalian species. Intact GnRH-II neuropeptide and receptor genes (GnRH2 and GnRH receptor 2 GnRHR2) occur in marmoset monkeys (Callithrix jacchus), musk shrews (Suncus murinus) and pigs (Sus scrofa). However, one or other or both of these genes are inactivated in other species, where mutations or remnants affecting GnRH2 neuropeptide and/or type II GnRHR exons are retained in conserved genomic loci. New data from DNA sequencing projects facilitate extensive analysis of species-specific variation in these genes. Here, we describe GnRH2 and GnRHR2 genes spanning a collection of 21 taxonomic orders, encompassing around 140 species from Primates, Scandentia, Eulipotyphla, Rodentia, Lagomorpha, Artiodactyla, Carnivora, Perissodactyls, Pholidota, Chiroptera, Afrotheria, Xenarthra and Marsupialia. Intact coding exons for both GnRH2 and GnRHR2 occur in monkeys, tree shrews, shrews, moles, hedgehogs, several rodents (degu, kangaroo-rat, pocket mouse), pig, pecarry and warthog, camels and alpaca, bears, Weddell seal, hyena, elephant, aardvark and marsupials. Inactivating mutations affecting GnRH2 and GnRHR2, some located at conserved sites within exons, occur in species of primates, most rodents, lagomorphs, bovidae, cetaceans, felidae, canidae and other carnivora, pangolins, most bats, armadillo, brushtail and echidna. A functional GnRH-II system appears retained within several taxonomic families of mammals, but intact retention does not extend to whole taxonomic orders. Defining how endogenous GnRH-II neuropeptide operates in different mammals may afford functional insight into its actions in the brain, especially as, unlike the type I GnRH system, it is expressed in the mid brain and not the hypothalamus.

Viruses Identified in Shrews (Soricidae) and Their Biomedical Significance.

Shrews (Soricidae) are common small wild mammals. Some species of shrews, such as Asian house shrews (Suncus murinus), have a significant overlap in their habitats with humans and domestic animals. Currently, over 190 species of viruses in 32 families, including Adenoviridae, Arenaviridae, Arteriviridae, Astroviridae, Anelloviridae, Bornaviridae, Caliciviridae, Chuviridae, Coronaviridae, Filoviridae, Flaviviridae, Hantaviridae, Hepadnaviridae, Hepeviridae, Nairoviridae, Nodaviridae, Orthoherpesviridae, Orthomyxoviridae, Paramyxoviridae, Parvoviridae, Phenuiviridae, Picobirnaviridae, Picornaviridae, Polyomaviridae, Poxviridae, Rhabdoviridae, Sedoreoviridae, Spinareoviridae, and three unclassified families, have been identified in shrews. Diverse shrew viruses, such as Borna disease virus 1, Langya virus, and severe fever with thrombocytopenia syndrome virus, cause diseases in humans and/or domestic animals, posing significant threats to public health and animal health. This review compiled fundamental information about shrews and provided a comprehensive summary of the viruses that have been detected in shrews, with the aim of facilitating a deep understanding of shrews and the diversity, epidemiology, and risks of their viruses.

Skull Shape Differences among Myanmar and Adjacent Populations of the House Shrew, Suncus murinus (Mammalia: Eulipotyphla): Insights into Allometry and Phylogenetic Variances Using Geometric Morphometrics

Skull Shape Differences among Myanmar and Adjacent Populations of the House Shrew, Suncus murinus (Mammalia: Eulipotyphla): Insights into Allometry and Phylogenetic Variances Using Geometric Morphometrics

Socio-environmental factors associated with small mammal assemblage and Leptospira prevalence in Suburban Areas of Terengganu, Malaysia

Objective: To examine the socio-environmental factors associated with the assemblage of small mammals and the prevalence of Leptospira pathogen in poor suburban communities of Terengganu, Malaysia. Methods: We trapped small mammals from 119 trapping points scattered around three suburban communities of Terengganu using sausage-baited live traps. On the average, we set up five traps for three nights at each sampling point during the trapping period. Kidneys of captured animals were harvested and processed for Leptospira investigation. Additionally, environmental survey was conducted at each trapping point to obtain information about possible variables supporting small mammal assemblage. We used a generalized linear model to evaluate the effect of different socio-environmental variables on small mammals’ assemblage. Results: A total of 89 small mammals, specifically, Rattus norvegicus (n=39), Rattus rattus (n=27), Rattus exulans (n=10), Suncus murinus (n=11), and Tupaia glis (n=2) were captured from 1 385 trap nights. Fourteen individuals (15.7%) of the captured animals tested positive for Leptospira bacteria using PCR detection. Results of our generalized linear model showed only residences bordering vacant lots as the variable positively associated with small mammal occurrence in the three study sites. Conclusions: Small mammal community, especially the often neglected species, could harbour and potentially contribute towards pathogenic Leptospira maintenance in the study sites. To adequately control small mammals’ population and subsequent human zoonoses transmission, it is critical to advocate and promote appropriate infrastructure and suburban services, together with good hygiene practices that can reduce the animals’ access to food and harborage.

Decoding the RNA viromes in shrew lungs along the eastern coast of China

Shrews being insectivores, serve as natural reservoirs for a wide array of zoonotic viruses, including the recently discovered Langya henipavirus (LayV) in China in 2018. It is crucial to understand the shrew-associated virome, viral diversity, and new viruses. In the current study, we conducted high-throughput sequencing on lung samples obtained from 398 shrews captured along the eastern coast of China, and characterized the high-depth virome of 6 common shrew species (Anourosorex squamipes, Crocidura lasiura, Crocidura shantungensis, Crocidura tanakae, Sorex caecutiens, and Suncus murinus). Our analysis revealed numerous shrew-associated viruses comprising 54 known viruses and 72 new viruses that significantly enhance our understanding of mammalian viruses. Notably, 34 identified viruses possess spillover-risk potential and six were human pathogenic viruses: LayV, influenza A virus (H5N6), rotavirus A, rabies virus, avian paramyxovirus 1, and rat hepatitis E virus. Moreover, ten previously unreported viruses in China were discovered, six among them have spillover-risk potential. Additionally, all 54 known viruses and 12 new viruses had the ability to cross species boundaries. Our data underscore the diversity of shrew-associated viruses and provide a foundation for further studies into tracing and predicting emerging infectious diseases originated from shrews.

Impacts of different pancreatic resection ranges on endocrine function in Suncus murinus.

Surgical intervention involving the pancreas can lead to impaired glucose tolerance and other types of endocrine dysfunction. The scope of pancreatectomy and whether it includes the ventral pancreas are the key factors in the development of postoperative diabetes. The ventral and dorsal pancreases are almost separated in Suncus murinus (S. murinus). To investigate the effects of different extents of pancreatic resection on endocrine function in S. murinus. Eight-week-old male S. murinus shrews were randomly divided into three experimental groups according to different pancreatic resection ranges as follows: ventral pancreatectomy (VPx) group; partial pancreatectomy (PPx) group; subtotal pancreatectomy (SPx) group; and a sham-operated group. Postprandial serum insulin, glucagon-like peptide-1 (GLP-1), pancreatic polypeptide (PP), and somatostatin (SST) levels, as well as food intake, weight, blood glucose, and glucose tolerance were regularly measured for each animal. S. murinus treated with PPx and SPx suffered from varying degrees of impaired glucose tolerance, but only a small proportion of the SPx group developed diabetes. Only S. murinus in the SPx group showed a significant decrease in food intake accompanied by severe weight loss, as well as a significant increase in postprandial serum GLP-1 levels. Postprandial serum PP levels decreased in both the VPx and PPx groups, but not in the SPx group. Postprandial serum SST levels decreased in both VPx and PPx groups, but the decrease was marginal. Severe weight loss after pancreatectomy may be related to loss of appetite caused by compensatory elevation of GLP-1. PP and GLP-1 may play a role in resisting blood glucose imbalance.

Bone microstructure as an indicator of digging ability in moles (Talpidae, Eulipotyphla).

Talpid moles (Talpidae, Eulipotyphla) are mammals highly specialised in burrowing using their forelimbs. Fossoriality has allowed moles to expand their ecological niche by enabling access to subterranean resources and spaces. This specialisation in burrowing has led to adaptations in the forelimb bones of moles for humeral rotation digging, a distinctive strategy unparalleled among other diggers. While bone robustness has been examined in moles through external morphology, the adaptation of bone microstructure to digging strategy remains unclear. Based on two assumptions, (1) the humerus of moles is subjected to a torsional load due to humeral rotation digging, and (2) the magnitude of torsional load correlates with the compactness of the substrate in which the individuals can dig, we hypothesised that humeral rotation digging influences bone microstructure. Comparative analyses of transverse sections from the humeri and femora of three mole species (Mogera imaizumii, Mogera wogura and Urotrichus talpoides; Talpidae) and an outgroup eulipotyphlan (Suncus murinus; Soricidae) revealed that (1) vascular canals distributed in the humeri of moles align more predominantly circumferential along the bone walls, indicating an adaptation to the torsion generated by humeral rotation digging, and (2) the laminarity of vascular canals, particularly in Mogera species compared with Urotrichus, potentially reflects differences in the magnitude of load due to substrate compactness during digging. The aligned vascular canals are distinctive traits not observed in mammals employing other digging strategies. This suggests that vascular canal laminarity can be an indicator of not only humeral rotation digging in fossorial animals, but also the variation of eco-spaces in talpid species.

Intrahepatic distribution of nerves in Suncus murinus by whole-mount immunohistological observation.

In recent years, elucidating the actual state of the liver nervous system has attracted attention, owing to clinical needs, such as liver transplantation. Conventional methods for studying the intrahepatic nerve distribution mostly use liver tissue sections, specific markers for immunohistological studies, or anterograde/retrograde tracing in animals. However, knowledge of the three-dimensional structure of intrahepatic innervation is vague or speculative. In this study, Suncus murinus (Suncus) (n = 10) were perfused and fixed, the livers were excised, and the liver parenchyma was carefully removed, leaving only the intrahepatic vasculature. Specimens were prepared to study the three-dimensional structure of Suncus intrahepatic and hilar innervation by whole-mount immunohistochemical staining using a neurofilament protein antibody. After the nerves running along the intrahepatic arterial system entered the liver parenchyma from the hepatic hilum, they maintained a relatively rich distribution along the interlobular arteries until the distal end. The innervation of the portal system began to decrease after entering the liver parenchyma and decreased significantly after reaching the deep parts. By the time it reached the end of the interlobular vein, there was very little left. The number of nerves running along the intrahepatic bile duct system was significantly reduced after entering the porta hepatis, and innervation was difficult to observe after completely entering the liver parenchyma. Whole-mount immunohistochemical analyses with an anti-NFP antibody showed that intrahepatic innervation mainly accompanied the hepatic interlobular arteries and extended to their terminal ends. Neuronal regulation is very important in the functional regulation of intrahepatic nutritional vessels. However, there were very few NFP-immunoreactive nerves accompanying the intrahepatic bile duct system, possibly suggesting that the functional regulation of the intrahepatic biliary system mainly relies on hormones and neuropeptides.

Molecular prevalence, subtype distribution, and zoonotic potential of Blastocystis sp. in wild rodents and shrews inhabiting Zhejiang province of China.

Globally, rodents and shrew populations constitute crucial elements of diverse environments and animal communities. It is imperative to study their population dynamics to mitigate any potential negative impact on humans, as they can be involved in the transmission of critical zoonotic agents, such as Blastocystis. Therefore, this study aimed to identify the prevalence and genetic composition of Blastocystis in wild rodents and shrews residing in the Zhejiang provinces of China. A total of 652 wild rodents and and shrews were captured from three different regions in Zhejiang Province from April 1st to October 31, 2023. The DNA was isolated by collecting fresh feces from the intestines of each rodent or and shrew. Rodent and shrew species were examined by vertebrate cytochrome b (cytb) analysis and PCR amplification. Blastocystis was also found in all fecal samples using PCR analysis and sequencing of the partial small subunit of ribosomal RNA (SSU rRNA) gene. Among all the samples, 6.6% (43/652) showed a positive result for Blastocystis. In the results, 6 species of rodent and shrew were identified with Blastocystis, including Apodemus agrarius (n = 36) (2.8%), Niviventer confucianus (n = 75) (17.3%), Rattus losea (n = 18) (5.6%), R. norvegicus (n = 155) (2.6%), R. tanezumi (n = 86) (3.5%), and Suncus murinus (n = 282) (7.4%). The existence of 6 Blastocystis subtypes, ST4 (n = 33), ST1 (4), ST7 (n = 3), ST2 (n = 1), ST3 (n = 1), and ST5 (n = 1), were confirmed by sequence analysis. Based on the molecular data obtained, the wild rodents and shrews under investigation were found to be concurrently infected with zoonotic subtypes of Blastocystis, including ST1 to ST5 and ST7. This suggests that these animals could potentially pose a zoonotic threat to humans and other animals susceptible to Blastocystis infection.

Insidensi Ortohantavirus pada Inang Reservoir di Kota Semarang, Jawa Tengah

Orthohantavirus is an RNA virus that causes Hemorrhagic Fever with Renal Syndrome (HFRS) and Hantavirus Pulmonary Syndrome (HPS). Humans can become infected with orthohantaviruses by inhaling virus particles from the urine, saliva, and feces of infective reservoir hosts. Small mammals from the orders Rodensia, Eulipotyphla, and Chiroptera are the main reservoirs of orthohantaviruses. This study aims to detect and calculate the incidence of orthohantavirus in reservoir hosts in Semarang City. The research was conducted descriptively analytically with a cross-sectional study design. The research population was all mice and shrews in the research location (Gayamsari and Tlogosari subdistricts), and the samples were caught mice and shrews (84). The research was carried out in May-September 2023. Orthohantavirus detection was carried out using the Nested PCR test (pre denaturation, denaturation, annealing and extension). A total of 84 individuals were captured, consisting of Rattus novergicus, Rattus tanezumi and Suncus murinus. Orthohantavirus in this study was successfully detected in Rattus norvegicus. The results of the study showed that the incidence of orthohantavirus in Gayamsari Village was (11.1%), Tlogosari Village (2.78%), and the overall total was (2.38%). It is necessary to control mice to prevent transmission of orthohantavirus.

Molecular detection and genetic variability of Cryptosporidium spp. in wild Asian house shrews (Suncus murinus) from southern Zhejiang province, China

Shrews play a crucial role as repositories for diverse pathogens linked to zoonotic infectious diseases. However, the genetic information regarding Cryptosporidium in Chinese shrews remains unexplored. The objectives of this study were twofold: to determine the occurrence rate of Cryptosporidium spp. in wild shrews residing in the southern part of Zhejiang Province, China, and to investigate their genetic characteristics. A total of 282 wild shrews were captured between April and October of 2023. The detection of Cryptosporidium in fecal samples, collected from each animal's rectum, was performed using PCR and sequencing of the partial small subunit of ribosomal RNA (SSU rRNA) gene. The 60-kDa glycoprotein (gp60) gene was utilized to further subtype the positive samples of C. viatorum and C. parvum. All animals were identified as Suncus murinus, and a positive result for Cryptosporidium was obtained in 14.2 % (40/282) of the samples. The following species and genotypes were identified: C. ratti (n = 19), C. parvum (n = 2), C. viatorum (n = 1), Cryptosporidium rat genotype IV (n = 13), and Cryptosporidium skunk genotype (n = 5). Furthermore, the subtypes IIdA15G1 and XVdA3 were detected within C. parvum and C. viatorum, respectively. Molecular evidence indicates that S. murinus is concurrently infected with rodent-adapted and zoonotic species/genotypes, actively contributing to the dissemination of cryptosporidiosis.

A molecular survey of zoonotic pathogens of public health importance in rodents/shrews and their ectoparasites trapped in Puducherry, India.

Globally, India has a high zoonotic disease burden and lacks surveillance data in humans and animals. Rodents are known reservoirs for many zoonotic diseases and their synanthropic behavior poses a great public health threat. In this study, trapped rodents/shrews from randomly selected villages within Puducherry, India, and their ectoparasites were screened for zoonotic pathogens, namely, Orientia tsutsugamushi, other pathogenic rickettsiae, Leptospira spp., Cryptosporidium spp., Coxiella burnetii and methicillin-resistant Staphylococcus aureus (MRSA) using conventional PCR. A total of 58 rodents/shrews were trapped from 11 villages. The species trapped were Suncus murinus (49/58, 84.48%), Rattus rattus (8/58, 13.79%) and Rattus norvegicus (1/58, 1.72%). All ectoparasites collected were identified as mites and its infestation rate was 46.55% (27/58). Real-time PCR targeting the 47 kDa gene of O. tsutsugamushi revealed positivity in one rodent and one shrew (3.45%) and two mite pools (7.41%). Conventional PCR targeting the 56 kDa gene revealed positivity in one shrew and two mite pools and the phylogenetic analysis of all three amplicons indicated the circulation of the Gilliam-related serotype. MRSA was detected in the alimentary tract of a shrew (1/32, 3.13%). Leptospira spp., Rickettsia, Cryptosporidium spp. and Co. burnetii tested negative. The detection of zoonotic pathogens within reservoir hosts and vectors poses a risk of transmission to humans. This study signifies the need for zoonotic pathogen surveillance in synanthropic rodents/shrews.

Enterocytozoon bieneusi in Wild Rats and Shrews from Zhejiang Province, China: Occurrence, Genetic Characterization, and Potential for Zoonotic Transmission.

Globally, Enterocytozoon bieneusi has been detected in humans and various animal hosts. Wild rats and shrews have the potential to act as carriers of E. bieneusi, facilitating the parasite's transmission to humans and domestic animals. We aimed to investigate the prevalence of E. bieneusi in 652 wild rats and shrews from Zhejiang Province, China, by amplifying the internal transcribed spacer (ITS) region of rDNA through polymerase chain reaction (PCR). To determine animal species, we amplified the Cytochrome b (Cyt-b) gene in their fecal DNA using PCR. Furthermore, we determined the genotype of E. bieneusi by amplifying the ITS region of rDNA through PCR. Genetic traits and zoonotic potential were evaluated using similarity and phylogenetic analyses. Suncus murinus (n = 282) and five rat species, Rattus losea (n = 18), Apodemus agrarius (n = 36), Rattus tanezumi (n = 86), Rattus norvegicus (n = 155), and Niviventer niviventer (n = 75), were identified. The average infection rate of E. bieneusi was 14.1% (92/652) with 18.1% (51/282) in S. murinus and 11.1% (41/370) in rats (27.8% in R. losea, 22.2% in A. agrarius, 10.5% in R. tanezumi, 8.4% in R. norvegicus, and 8.0% in N. niviventer). Thirty-three genotypes were identified, including 16 known genotypes. The most commonly known genotypes were HNR-VI (n = 47) and Peru11 (n = 6). Type IV, KIN-1, SHW7, and HNPL-II were each found in two samples, while Macaque4, CH5, K, Henan-III, Henan-V, HNP-II, HNPL-I, HNPL-III, HNHZ-II, and HNHZ-III were each found in one sample. Additionally, 17 novel genotypes were discovered: WZR-VIII (n = 5), WZR-I to WZR-VII, WZR-IX to WZR-XII, and WZSH-I to WZSH-V (n = 1 each). Those 33 genotypes were divided into three groups: Group 1 (n = 25), Group 2 (n = 3), and Group 13 (n = 5). The initial report underscores the extensive occurrence and notable genetic diversity of E. bieneusi in wild rats and shrews from Zhejiang province, China. These results suggest that these animals play a pivotal role in the transmission of E. bieneusi. Furthermore, animals carrying the zoonotic genotypes of E. bieneusi pose a serious threat to residents.

Pathological Responses in Asian House Shrews (Suncus murinus) to the Naturally Acquired Orientia tsutsugamushi Infection.

Scrub typhus is a re-emerging disease caused by Orientia tsutsugamushi, transmitted by mites belonging to the family Trombiculidae. Humans and rodents acquire the infection by the bite of larval mites/chiggers. Suncus murinus, the Asian house shrew, has been reported to harbor the vector mites and has been naturally infected with O. tsutsugamushi. The present study aimed to localize and record O. tsutsugamushi in the tissues and the host response in shrews naturally infected with O. tsutsugamushi. Sheehan's modified May-Grunwald Giemsa staining was carried out in 365 tissues from 87 animals, and rickettsiae were documented in 87 tissues from 20 animals. Immunohistochemical (IHC) staining, using polyclonal antibodies raised against selected epitopes of the 56-kDa antigen, was carried out, and 81/87 tissue sections were tested positive for O. tsutsugamushi. By IHC, in addition to the endothelium, the pathogen was also demonstrated by IHC in cardiomyocytes, the bronchiolar epithelium, stroma of the lungs, hepatocytes, the bile duct epithelium, the epithelium and goblet cells of intestine, the tubular epithelium of the kidney, and splenic macrophages. Furthermore, the pathogen was confirmed by real-time PCR using blood (n = 20) and tissues (n = 81) of the IHC-positive animals. None of the blood samples and only 22 out of 81 IHC-positive tissues were tested positive by PCR. By nucleotide sequencing of the 56-kDa gene, Gilliam and Karp strains were found circulating among these animals. Although these bacterial strains are highly virulent and cause a wide range of pathological alterations, hence exploring their adaptive mechanisms of survival in shrews will be of significance. Given that the pathogen localizes in various organs following a transient bacteremia, we recommend the inclusion of tissues from the heart, lung, intestine, and kidney of reservoir animals, in addition to blood samples, for future molecular surveillance of scrub typhus.

Exploring the role of ghrelin and des-acyl ghrelin in chemotherapy-induced nausea and vomiting

Ghrelin and its mimetics have been shown to reduce cisplatin-induced emesis in preclinical studies using ferrets and shrews. This study investigated the effectiveness of ghrelin and des-acyl ghrelin (DAG) in antagonizing cisplatin-induced emesis and physiological changes indicative of nausea in Suncus murinus. Animals implanted with radiotelemetry devices were administered ghrelin (0.2, 1.0, and 5.0 μg/day), DAG (0.2, 1.0, and 5.0 μg/day), or saline (14 μL/day) intracerebroventricularly 4 days before and 3 days after treatment with cisplatin (30 mg/kg). At the end, the anti-apoptotic potentials of ghrelin and DAG were assessed by measuring Bax expression and cytochrome C activity. Neurotransmitter changes in the brain were evaluated using liquid chromatography–mass spectrometry analysis. Ghrelin and DAG reduced cisplatin-induced emesis in the delayed (24–72 h) but not the acute phase (0–24 h) of emesis. Ghrelin also partially reversed the inhibitory effects of cisplatin on food intake without affecting gastrointestinal myoelectrical activity or causing hypothermia; however, ghrelin or DAG did not prevent these effects. Ghrelin and DAG could attenuate the cisplatin-induced upregulation of Bax and cytochrome C in the ileum. Cisplatin dysregulated neurotransmitter levels in the frontal cortex, amygdala, thalamus, hypothalamus, and brainstem, and this was partially restored by low doses of ghrelin and DAG. Our findings suggest that ghrelin and DAG exhibit protective effects against cisplatin-induced delayed emesis. The underlying antiemetic mechanism may involve GHSR and/or unspecified pathways that modulate the neurotransmitters involved in emesis control in the brain and an action to attenuate apoptosis in the gastrointestinal tract.

Surveillance of Fleas and Their Small Mammal Hosts for Plague Risks in Some Main Seaports of the Islands of the Southwestern Indian Ocean.

Since ancient times, seaports have been the hot spots for plague introduction into free countries. Infected ship rats reached new areas, and epizootics occurred prior to human infection via flea bites. Beginning in the 1920s/1930s, rodent and flea surveillance was carried out as part of plague hazard management in seaports of the world. Nowadays, such activity is not done regularly. In the southwestern Indian Ocean (SWIO) region, plague surveillance is of great importance given plague endemicity in Madagascar and thus the incurred risk for neighboring islands. This study reports animal-based surveillance aimed at identifying fleas and their small mammal hosts in SWIO seaports as well as Yersinia pestis detection. Small mammal trappings were performed in five main seaports of Madagascar (Toamasina and Mahajanga), Mauritius (Port Louis), and the Union of Comoros (Moroni and Mutsamudu). Mammals were euthanized and their fleas collected and morphologically identified before Y. pestis detection. In total, 145 mammals were trapped: the brown rat Rattus norvegicus (76.5%), the black rat Rattus rattus (8.3%), and the Asian house shrew Suncus murinus (15.2%). Fur brushing allowed collection of 1,596 fleas exclusively identified as Xenopsylla cheopis. All tested fleas were negative for Y. pestis DNA. This study shows that both well-known plague mammal hosts and flea vectors occur in SWIO seaports. It also highlights the necessity of carrying out regular animal-based surveillance for plague hazard management in this region.

Phylogenetics and Population Genetics of the Asian House Shrew, Suncus murinus-S. montanus Species Complex, Inferred From Whole-Genome and Mitochondrial DNA Sequences, with Special Reference to the Ryukyu Archipelago, Japan.

The house shrew (Suncus murinus-S. montanus species complex) colonized regions across southern Asia and the Indian Ocean following human activity. The house shrew is distributed on islands of the Ryukyu Archipelago, the southernmost part of Japan, but the evolutionary history of the shrew on those islands and possible associations between these populations and humans remain unknown. In this study, we conducted phylogenetic and population genetic analyses based on both nuclear and mitochondrial genome sequences of house shrews. Phylogenetic analyses based on mitochondrial cytochrome b (cytb) sequences revealed that shrews from the Ryukyu Archipelago showed strong genetic affinity to Vietnamese and southern Chinese shrews. Demographic analyses of cytb sequences indicated a rapid population expansion event affecting the haplotype group in Vietnam, southern China, and the Ryukyu Archipelago 3300-7900 years ago. Furthermore, gene flow between Ryukyu (Yonaguni Island) and Taiwan and between Ryukyu and Vietnam inferred from f4 statistics of the nuclear genomes suggested repeated immigration to Ryukyu in recent years. The present study demonstrates that the Nagasaki population has a different origin from the Ryukyu population. These findings elucidate the complex pattern of genetic admixture in house shrews and provide insights into their evolutionary history.