The impact of within-host coinfection interactions on between-host parasite transmission dynamics varies with spatial scale.

Within-host interactions among coinfecting parasites can have major consequences for individual infection risk and disease severity. However, the impact of these within-host interactions on between-host parasite transmission, and the spatial scales over which they occur, remain unknown. We developed and apply a novel spatially explicit analysis to parasite infection data from a wild wood mouse (Apodemus sylvaticus) population. We previously demonstrated a strong within-host negative interaction between two wood mouse gastrointestinal parasites, the nematode Heligmosomoides polygyrus and the coccidian Eimeria hungaryensis, using drug-treatment experiments. Here, we show this negative within-host interaction can significantly alter the between-host transmission dynamics of E. hungaryensis, but only within spatially restricted neighbourhoods around each host. However, for the closely related species E. apionodes, which experiments show does not interact strongly with H. polygyrus, we did not find any effect on transmission over any spatial scale. Our results demonstrate that the effects of within-host coinfection interactions can ripple out beyond each host to alter the transmission dynamics of the parasites, but only over local scales that likely reflect the spatial dimension of transmission. Hence there may be knock-on consequences of drug treatments impacting the transmission of non-target parasites, altering infection risks even for non-treated individuals in the wider neighbourhood.

Rodent control strategies and Lassa virus: some unexpected effects in Guinea, West Africa.

The Natal multimammate mouse (Mastomys natalensis) is the host of Lassa mammarenavirus, causing Lassa haemorrhagic fever in West Africa. As there is currently no operational vaccine and therapeutic drugs are limited, we explored rodent control as an alternative to prevent Lassa virus spillover in Upper Guinea, where the disease is highly endemic in rural areas. In a seven-year experiment, we distributed rodenticides for 10-30 days once a year and, in the last year, added intensive snap trapping for three months in all the houses of one village. We also captured rodents both before and after the intervention period to assess their effectiveness by examining alterations in trapping success and infection rates (Lassa virus RNA and IgG antibodies). We found that both interventions reduced the rodent population by 74-92% but swiftly rebounded to pre-treatment levels, even already six months after the last snap-trapping control. Furthermore, while we observed that chemical control modestly decreased Lassa virus infection rates annually (a reduction of 5% in seroprevalence per year), the intensive trapping unexpectedly led to a significantly higher infection rate (from a seroprevalence of 28% before to 67% after snap trapping control). After seven years, we conclude that annual chemical control, alone or with intensive trapping, is ineffective and sometimes counterproductive in preventing Lassa virus spillover in rural villages. These unexpected findings may result from density-dependent breeding compensation following culling and the survival of a small percentage of chronically infected rodents that may spread the virus to a new susceptible generation of mice.

Characterisation of the mitochondrial genome and phylogenetic analysis of Toxocara apodemi (Nematoda: Ascarididae).

We first sequenced and characterised the complete mitochondrial genome of Toxocara apodeme, then studied the evolutionary relationship of the species within Toxocaridae. The complete mitochondrial genome was amplified using PCR with 14 specific primers. The mitogenome length was 14303 bp in size, including 12 PCGs (encoding 3,423 amino acids), 22 tRNAs, 2 rRNAs, and 2 NCRs, with 68.38% A+T contents. The mt genomes of T. apodemi had relatively compact structures with 11 intergenic spacers and 5 overlaps. Comparative analyses of the nucleotide sequences of complete mt genomes showed that T. apodemi had higher identities with T. canis than other congeners. A sliding window analysis of 12 PCGs among 5 Toxocara species indicated that nad4 had the highest sequence divergence, and cox1 was the least variable gene. Relative synonymous codon usage showed that UUG, ACU, CCU, CGU, and UCU most frequently occurred in the complete genomes of T. apodemi. The Ka/Ks ratio showed that all Toxocara mt genes were subject to purification selection. The largest genetic distance between T. apodemi and the other 4 congeneric species was found in nad2, and the smallest was found in cox2. Phylogenetic analyses based on the concatenated amino acid sequences of 12 PCGs demonstrated that T. apodemi formed a distinct branch and was always a sister taxon to other congeneric species. The present study determined the complete mt genome sequences of T. apodemi, which provide novel genetic markers for further studies of the taxonomy, population genetics, and systematics of the Toxocaridae nematodes.

Reservoir displacement by an invasive rodent reduces Lassa virus zoonotic spillover risk.

The black rat (Rattus rattus) is a globally invasive species that has been widely introduced across Africa. Within its invasive range in West Africa, R. rattus may compete with the native rodent Mastomys natalensis, the primary reservoir host of Lassa virus, a zoonotic pathogen that kills thousands annually. Here, we use rodent trapping data from Sierra Leone and Guinea to show that R. rattus presence reduces M. natalensis density within the human dwellings where Lassa virus exposure is most likely to occur. Further, we integrate infection data from M. natalensis to demonstrate that Lassa virus zoonotic spillover risk is lower at sites with R. rattus. While non-native species can have numerous negative effects on ecosystems, our results suggest that R. rattus invasion has the indirect benefit of decreasing zoonotic spillover of an endemic pathogen, with important implications for invasive species control across West Africa.

Social and environmental transmission spread different sets of gut microbes in wild mice.

Gut microbes shape many aspects of organismal biology, yet how these key bacteria transmit among hosts in natural populations remains poorly understood. Recent work in mammals has emphasized either transmission through social contacts or indirect transmission through environmental contact, but the relative importance of different routes has not been directly assessed. Here we used a novel radio-frequency identification-based tracking system to collect long-term high-resolution data on social relationships, space use and microhabitat in a wild population of mice (Apodemus sylvaticus), while regularly characterizing their gut microbiota with 16S ribosomal RNA profiling. Through probabilistic modelling of the resulting data, we identify positive and statistically distinct signals of social and environmental transmission, captured by social networks and overlap in home ranges, respectively. Strikingly, microorganisms with distinct biological attributes drove these different transmission signals. While the social network effect on microbiota was driven by anaerobic bacteria, the effect of shared space was most influenced by aerotolerant spore-forming bacteria. These findings support the prediction that social contact is important for the transfer of microorganisms with low oxygen tolerance, while those that can tolerate oxygen or form spores may be able to transmit indirectly through the environment. Overall, these results suggest social and environmental transmission routes can spread biologically distinct members of the mammalian gut microbiota.

Where Are the Formerly Y-linked Genes in the Ryukyu Spiny Rat that has Lost its Y Chromosome?

It has been predicted that the highly degenerate mammalian Y chromosome will be lost eventually. Indeed, Y was lost in the Ryukyu spiny rat Tokudaia osimensis, but the fate of the formerly Y-linked genes is not completely known. We looked for all 12 ancestrally Y-linked genes in a draft T. osimensis genome sequence. Zfy1, Zfy2, Kdm5d, Eif2s3y, Usp9y, Uty, and Ddx3y are putatively functional and are now located on the X chromosome, whereas Rbmy, Uba1y, Ssty1, Ssty2, and Sry are missing or pseudogenized. Tissue expressions of the mouse orthologs of the retained genes are significantly broader/higher than those of the lost genes, suggesting that the destinies of the formerly Y-linked genes are related to their original expressions. Interestingly, patterns of gene retention/loss are significantly more similar than by chance across four rodent lineages where Y has been independently lost, indicating a level of certainty in the fate of Y-linked genes even when the chromosome is gone.

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Antibiotic resistance genes (ARGs) have attracted widespread attention as a new global pollutant, mainly due to the abuse of antibiotics. To investigate the diversity of ARGs in three rodent species, we used metagenomic sequencing analysis to analyze the diversity of antibiotic resistance genes of 17 individuals of Apodemus peninsulae and 17 individuals of Myodes rufocanus collected from Mudanfeng, and nine individuals of Apodemus agrarius collected from Sandaoguan. A total of 19 types and 248 subclasses of ARGs were detected in the three rodent species. Seven ARGs showed significant difference and five ARGs showed extremely significant difference between M. rufocanus and A. agrarius. Seven ARGs showed significant difference and four ARGs showed extremely significant difference between A. peninsulae and A. agrarius. Four ARGs showed significant difference and five ARGs showed extremely significant difference between M. rufocanus and A. peninsulae. ARGs showing high abundance in three rodents were macrolides, lincoamides, tetracyclines, and ß-lactams. ARGs were widely distributed in the three rodent species. The significant differences in ARGs among different species might be due to the different distribution areas and their diet differentiation. The study could provide a basis for further studies of ARGs in mice and improve the understanding of the harm of ARGs transmission.

A cyst-forming coccidian with large geographical range infecting forest and commensal rodents: Sarcocystis muricoelognathis sp. nov.

BACKGROUND: The geographic distribution and host-parasite interaction networks of Sarcocystis spp. in small mammals in eastern Asia remain incompletely known. METHODS: Experimental infections, morphological and molecular characterizations were used for discrimination of a new Sarcocystis species isolated from colubrid snakes and small mammals collected in Thailand, Borneo and China. RESULTS: We identified a new species, Sarcocystis muricoelognathis sp. nov., that features a relatively wide geographic distribution and infects both commensal and forest-inhabiting intermediate hosts. Sarcocystis sporocysts collected from rat snakes (Coelognathus radiatus, C. flavolineatus) in Thailand induced development of sarcocysts in experimental SD rats showing a type 10a cyst wall ultrastructure that was identical with those found in Rattus norvegicus from China and the forest rat Maxomys whiteheadi in Borneo. Its cystozoites had equal sizes in all intermediate hosts and locations, while sporocysts and cystozoites were distinct from other Sarcocystis species. Partial 28S rRNA sequences of S. muricoelognathis from M. whiteheadi were largely identical to those from R. norvegicus in China but distinct from newly sequenced Sarcocystis zuoi. The phylogeny of the nuclear 18S rRNA gene placed S. muricoelognathis within the so-called S. zuoi complex, including Sarcocystis attenuati, S. kani, S. scandentiborneensis and S. zuoi, while the latter clustered with the new species. However, the phylogeny of the ITS1-region confirmed the distinction between S. muricoelognathis and S. zuoi. Moreover, all three gene trees suggested that an isolate previously addressed as S. zuoi from Thailand (KU341120) is conspecific with S. muricoelognathis. Partial mitochondrial cox1 sequences of S. muricoelognathis were almost identical with those from other members of the group suggesting a shared, recent ancestry. Additionally, we isolated two partial 28S rRNA Sarcocystis sequences from Low's squirrel Sundasciurus lowii that clustered with those of S. scandentiborneensis from treeshews. CONCLUSIONS: Our results provide strong evidence of broad geographic distributions of rodent-associated Sarcocystis and host shifts between commensal and forest small mammal species, even if the known host associations remain likely only snapshots of the true associations.

Degeneration of the Olfactory System in a Murid Rodent that Evolved Diurnalism.

In mammalian research, it has been debated what can initiate an evolutionary tradeoff between different senses, and the phenomenon of sensory tradeoff in rodents, the most abundant mammalian clade, is not evident. The Nile rat (Arvicanthis niloticus), a murid rodent, recently adapted to a diurnal niche through an evolutionary acquisition of daylight vision with enhanced visual acuity. As such, this model provides an opportunity for a cross-species investigation where comparative morphological and multi-omic analyses of the Nile rat are made with its closely related nocturnal species, e.g. the mouse (Mus musculus) and the rat (Rattus norvegicus). Thus, morphological examinations were performed, and evolutionary reductions in relative sizes of turbinal bone surfaces, the cribriform plate, and the olfactory bulb were discovered in Nile rats. Subsequently, we compared multiple murid genomes, and profiled olfactory epithelium transcriptomes of mice and Nile rats at various ages with RNA sequencing. The results further demonstrate that, in comparison with mouse olfactory receptor (OR) genes, Nile rat OR genes have experienced less frequent gain, more frequent loss, and more frequent expression reduction during their evolution. Furthermore, functional degeneration of coding sequences in the Nile rat lineage was found in OR genes, yet not in other genes. Taken together, these results suggest that acquisition of improved vision in the Nile rat has been accompanied by degeneration of both olfaction-related anatomical structures and OR gene repertoires, consistent with the hypothesis of an olfaction-vision tradeoff initiated by the switch from a nocturnal to a diurnal lifestyle in mammals.

Speciation across biomes: Rapid diversification with reproductive isolation in the Australian delicate mice.

Phylogeographic studies of continental clades, especially when combined with palaeoclimate modelling, provide powerful insight into how environment drives speciation across climatic contexts. Australia, a continent characterized by disparate modern biomes and dynamic climate change, provides diverse opportunity to reconstruct the impact of past and present environments on diversification. Here, we use genomic-scale data (1310 exons and whole mitogenomes from 111 samples) to investigate Pleistocene diversification, cryptic diversity, and secondary contact in the Australian delicate mice (Hydromyini: Pseudomys), a recent radiation spanning almost all Australian environments. Across northern Australia, we find no evidence for introgression between cryptic lineages within Pseudomys delicatulus sensu lato, with palaeoclimate models supporting contraction and expansion of suitable habitat since the last glacial maximum. Despite multiple contact zones, we also find little evidence of introgression at a continental scale, with the exception of a potential hybrid zone in the mesic biome. In the arid zone, combined insights from genetic data and palaeomodels support a recent expansion in the arid specialist P. hermannsburgensis and contraction in the semi-arid P. bolami. In the face of repeated secondary contact, differences in sperm morphology and chromosomal rearrangements are potential mechanisms that maintain species boundaries in these recently diverged species. Additionally, we describe the western delicate mouse as a new species and recommend taxonomic reinstatement of the eastern delicate mouse. Overall, we show that speciation in an evolutionarily young and widespread clade has been driven by environmental change, and potentially maintained by divergence in reproductive morphology and chromosome rearrangements.

Etiological agent and clinical characteristics of haemorrhagic fever with renal syndrome in the southern Republic of Korea: a genomic surveillance study.

OBJECTIVES: High incidences of haemorrhagic fever with renal syndrome (HFRS) have been reported in the southern Republic of Korea (ROK). A distinct southern genotype of Orthohantavirus hantanense (HTNV) was identified in Apodemus agrarius chejuensis on Jeju Island. However, its association with HFRS cases in southern ROK remains elusive. We investigated the potential of the southern HTNV genotype as an etiological agent of HFRS. METHODS: Samples from 22 patients with HFRS and 193 small mammals were collected in the southern ROK. The clinical characteristics of patients infected with the southern HTNV genotype were analysed. Amplicon-based MinION sequencing was employed for southern HTNV from patients and rodents, facilitating subsequent analyses involving phylogenetics and genetic reassortment. RESULTS: High-throughput sequencing of HTNV exhibited higher coverage with a cycle of threshold value below 32, acquiring nearly whole-genome sequences from six patients with HFRS and seven A. agrarius samples. The phylogenetic pattern of patient-derived HTNV demonstrated genetic clustering with HTNV from Apodemus species on Jeju Island and the southern Korean peninsula, revealing genetic reassortment in a single clinical sample between the M and S segments. DISCUSSION: These findings imply that the southern HTNV genotype has the potential to induce HFRS in humans. The phylogenetic inference demonstrates the diverse and dynamic characteristics of the southern HTNV tripartite genomes. Therefore, this study highlights the significance of active surveillance and amplicon sequencing for detecting orthohantavirus infections. It also raises awareness and caution for physicians regarding the emergence of a southern HTNV genotype as a cause of HFRS in the ROK.

Structural consistency of exploratory behaviour of sub-adult and adult spiny mice (Acomys cahirinus) in seven different tests.

The genus Acomys is of growing importance to many research fields. Previous research has shown that individuals differ when exploring new environments and that these behavioural strategies are consistent in time. In this study, we subjected 60 commensal Acomys cahirinus (37 males, 23 females) to a series of seven tests (free exploration, forced exploration under bright illumination, forced exploration under low illumination, hole board test, vertical activity test, elevated plus maze, and voluntary wheel running) to acquire independent behavioural traits and investigate whether and how personality develops in spiny mice. The full series of experiments was performed twice during ontogeny: once in the sub-adult stage (tested at 62-72 days of age) and once in the adult stage (102-112 days of age). We found that behaviour of the animals was repeatable both within (range of R values from 0.155 to 0.726) and across the two life-stages (0.238 to 0.563). While the structure of behaviour in adults was rather clear, it had not been fully crystalized in sub-adults, suggesting personality changes during maturation, even though some individual traits might be repeatable across ontogeny. Notably, the most consistent behavioural traits across the different tests were jumping and rearing, which are not commonly reported.

A recent gibbon ape leukemia virus germline integration in a rodent from New Guinea.

Germline colonization by retroviruses results in the formation of endogenous retroviruses (ERVs). Most colonization's occurred millions of years ago. However, in the Australo-Papuan region (Australia and New Guinea), several recent germline colonization events have been discovered. The Wallace Line separates much of Southeast Asia from the Australo-Papuan region restricting faunal and pathogen dispersion. West of the Wallace Line, gibbon ape leukemia viruses (GALVs) have been isolated from captive gibbons. Two microbat species from China appear to have been infected naturally. East of Wallace's Line, the woolly monkey virus (a GALV) and the closely related koala retrovirus (KoRV) have been detected in eutherians and marsupials in the Australo-Papuan region, often vertically transmitted. The detected vertically transmitted GALV-like viruses in Australo-Papuan fauna compared to sporadic horizontal transmission in Southeast Asia and China suggest the GALV-KoRV clade originates in the former region and further models of early-stage genome colonization may be found. We screened 278 samples, seven bat and one rodent family endemic to the Australo-Papuan region and bat and rodent species found on both sides of the Wallace Line. We identified two rodents (Melomys) from Australia and Papua New Guinea and no bat species harboring GALV-like retroviruses. Melomys leucogaster from New Guinea harbored a genomically complete replication-competent retrovirus with a shared integration site among individuals. The integration was only present in some individuals of the species indicating this retrovirus is at the earliest stages of germline colonization of the Melomys genome, providing a new small wild mammal model of early-stage genome colonization.

Vector competence of Ixodes ricinus instars for the transmission of Borrelia burgdorferi sensu lato in different small mammalian hosts.

BACKGROUND: Many pathogens and parasites can infect multiple host species, and the competence of different hosts as pathogen reservoirs is key to understanding their epidemiology. Small mammals are important hosts for the instar stages of Ixodes ricinus ticks, the principal vector of Lyme disease in Europe. Small mammals also act as reservoirs of Borrelia afzelii, the most common genospecies of the Borrelia burgdorferi sensu lato (s.l.) spirochetes causing Lyme disease in Europe. However, we lack quantitative estimates on whether different small mammal species are equally suitable hosts for feeding I. ricinus and whether they show differences in pathogen transmission from host to tick. METHODS: Here, we analysed the feeding success and prevalence of B. burgdorferi s.l. infections in 12,987 instar I. ricinus found on captured small mammals with known infection status in Norway (2018-2022). RESULTS: We found that larvae were more likely to acquire a blood meal from common shrews (Sorex araneus, 46%) compared to bank voles (Myodes glareolus, 36%) and wood mice (Apodemus sylvaticus, 31%). Nymphs tended to be more likely to acquire a blood meal from wood mice (66%) compared to bank voles (54%). Common shrews harboured few nymphs (n=19). Furthermore, we found that larvae feeding on infected bank voles (11%) were more likely to be infected with B. burgdorferi s.l. than larvae on infected common shrews (7%) or wood mice (4%). CONCLUSIONS: Our study provides quantitative evidence of differences in suitability for the instar stages of I. ricinus across taxa of small mammals and highlights how even known small mammal host species can differ in their ability to feed ticks and infect larval ticks with the pathogen causing Lyme disease.

Seasonal and age-dependent differences in mercury concentrations in Apodemus sp. in the north-western region of Slovakia.

Pollution of ecosystems by heavy metals such as mercury is currently a great concern. Mercury (Hg) can be released into the environment anthropogenically, but it is also naturally present in small quantities in all environmental compartments. Many different factors contribute to different rates of Hg deposition in animal bodies. The aim of this work is to describe how Hg concentrations in the bodies of small rodents change throughout the season at a site where massive anthropogenic pollution is not expected. Mice of the genus Apodemus were sampled during the whole year. Samples of blood, hair, liver, kidney, and brain were analyzed. Total Hg concentrations were measured by DMA-80. The mean Hg concentrations in examined organs were in the order hairs > kidney > liver > blood > brain, and their values decreased from 0.0500 to 0.0046 mg kg-1 dry weight. Males and females did not differ in contamination levels, but age-dependent differences in Hg concentrations were found. It was also identified how Hg concentrations in different organs correlate with each other. Different levels of seasonal variability were detected in Hg concentrations in blood, hair, and kidney.

Epidemiology of Hemorrhagic Fever with Renal Syndrome and Host Surveillance in Zhejiang Province, China, 1990-2021.

Hemorrhagic fever with renal syndrome (HFRS) is caused by hantaviruses (HVs) and is endemic in Zhejiang Province, China. In this study, we aimed to explore the changing epidemiology of HFRS cases and the dynamics of hantavirus hosts in Zhejiang Province. Joinpoint regression was used to analyze long-term trends in the incidence of HFRS. The comparison of animal density at different stages was conducted using the Mann-Whitney Test. A comparison of HV carriage rates between stages and species was performed using the chi-square test. The incidence of HFRS shows a continuous downward trend. Cases are widely distributed in all counties of Zhejiang Province except Shengsi County. There was a high incidence belt from west to east, with low incidence in the south and north. The HFRS epidemic showed two seasonal peaks in Zhejiang Province, which were winter and summer. It showed a marked increase in the age of the incidence population. A total of 23,073 minibeasts from 21 species were captured. Positive results were detected in the lung tissues of 14 rodent species and 1 shrew species. A total of 80% of the positive results were from striped field mice and brown rats. No difference in HV carriage rates between striped field mice and brown rats was observed (χ2 = 0.258, p = 0.611).

Genomic characterization of Rocahepevirus ratti hepatitis E virus genotype C1 in Yunnan province of China.

The Rocahepevirus ratti hepatitis E virus genotype C1 (HEV-C1) has been documented to infect humans. However, the understanding of HEV-C1 remains constrained. This study aims to determine the prevalence and genomic characteristics of HEV-C1 in small animals in Yunnan province of southwestern China. A total of 444 liver tissues were collected from animals covering the orders Rodentia, Soricomorpha, Scandentia and Erinaceomorpha in three regions in Yunnan. Then Paslahepevirus balayani and Rocahepevirus were examined using RT-qPCR. The detection rate of Rocahepevirus was 12.95 % (36/278) in animals of order Rodentia, with 14.77 % (35/237) in Rattus tanezumi and 33.33 % (1/3) in Niviventer fulvescens. No Paslahepevirus balayani was detected. Additionally, two full-length Rocahepevirus sequences (MSE-17 and LHK-54) and thirty-three partial ORF1 sequences were amplified and determined to be HEV-C1. MSE-17 and LHK-54 shared moderate nucleotide identity (78.9 %-80.3 %) with HEV-C1 isolated in rats and humans. The HEV-C1 isolated from Niviventer fulvescens demonstrated a 100 % nucleotide identity with that from Rattus tanezumi. The rat HEV-C1 sequences isolated in our study and other Asian HEV-C1 sequences were phylogenetically distant from those isolated in North America and Europe. Furthermore, the two full-length sequences isolated in our study had less amino acid substitutions in the motifs of RNA-dependent RNA polymerase domain (F204L and L238F), compared with other Asian sequences. In summary, HEV-C1 commonly spreads in rats in Yunnan province of China. Our findings suggest a spatially associated phylogeny, and potential cross-species transmission of HEV-C1.

Adiaspiromycoses in Wild Rodents from the Pyrenees, Northeastern Spain.

Adiaspiromycosis is a nontransmissible infectious pulmonary disease caused by the inhalation of propagules from fungal species belonging to the family Ajellomicetaceae, especially Emergomyces crescens. Adiaspiromycosis caused by E. crescens has been recorded in a broad number of species worldwide, with small burrowing mammals being considered the main hosts for this environmental pathogen. Only a handful of studies on adiaspiromycosis in European wildlife has been published to date. We assessed the occurrence of adiaspiromycosis in wild rodents (Murinae and Arvicolinae) from the central Spanish Pyrenees (NE Spain). The lungs of 302 mice and 46 voles were screened for the presence of adiaspores through histopathologic examination. Pulmonary adiaspiromycosis was recorded in 21.6% of all individuals (75/348), corresponding to 63/299 wood mice (Apodemus sylvaticus) and 12/40 bank voles (Myodes glareolus). Adiaspore burden varied highly between animals, with a mean of 0.19 spores/mm2 and a percentage of affected lung tissue ranging from <0.01% to >8%. These results show that the infection is present in wild rodents from the central Spanish Pyrenees. Although the impact of this infection on nonendangered species is potentially mild, it might contribute to genetic diversity loss in endangered species.

[Analysis on the characteristics of natural foci of hemorrhagic fever with renal syndrome in Gansu Province, 2012-2022].

Objective: To explore the characteristics of natural foci of hemorrhagic fever with renal syndrome (HFRS) in Gansu Province. Methods: The information of HFRS case data and rodent density monitoring data from 2012 to 2022 in Gansu Province were collected and epidemiological methods were used to analyze and investigate the characteristics of the epidemic focus. Results: A total of 869 cases of HFRS were reported, and four patients died from 2012 to 2022. The annual incidence rate is between 0.05 per 100 000 and 1.21 per 100 000. The cases were mainly distributed in the eastern, southeast, southern, and south of the central region of Gansu Province. Most cases were distributed between age 20-60, and the sex ratio was 1.85∶1 (564∶305). Most cases were farmers (61.80%, 537/869), herdsmen (19.79%,172/869) and students (6.33%, 55/869). In a wild rat-type epidemic focus,the incidence peak was from November to January of the following year. The natural rodent hosts of HFRS were Rattus norvegicus, Apodemus agrarius, and Mus musculus. The hantaan virus carriage rates were 2.79% (21/754), 0.42% (5/1 179) and 0.31% (2/643),respectively. Three epidemic foci were defined: two derived from the Pingliang and Gannan prefecture new outbreaks epidemic foci, respectively, while the other was the residue of the Dingxi epidemic focus. Conclusions: The southern, south of the central region and eastern part of Gansu Province are current key HFRS epidemic foci dominated by Rattus norvegicus, Apodemus agrarius, and Mus musculus, respectively. The virus genotype is hantaan virus. Case reporting areas should strengthen epidemic monitoring; the key epidemic areas should strengthen and implement various prevention and control measures to reduce the harm caused by HFRS.

[Monitoring and analysis on host animals of hemorrhagic fever with renal syndrome in Henan Province from 2019 to 2022].

Objective: To investigate the distribution and hantavirus (HV) carrying state in host animals of hemorrhagic fever with renal syndrome (HFRS) in Henan Province from 2019 to 2022. Methods: Host animal monitoring was carried out at the monitoring sites of HFRS in Henan Province. The real-time fluorescence quantitative PCR was used to detect hantavirus in rat lungs. The types of hantavirus were analyzed. The positive samples were sequenced and then sequence homology and variation were analyzed. Results: A total of 1 308 rodents were captured from 2019 to 2022, 16 specimens of rat lungs tested positive for hantavirus nucleic acid. The positive rate of HV was 1.22% (16/1 308). According to type, the positive rate of HV in Apodius agrarius was the highest (68.75%, 11/16). According to distribution, the positive rate of HV in field samples was the highest (2.50%, 12/480), and the positive rate of HV in residential samples was 0.53% (4/759). The typing results of 16 positive samples showed that all viruses were hantavirus type Ⅰ (hantaan virus). The positive samples were sequenced and eight S gene fragments (GenBank number: OQ681444-OQ681451) and six M gene fragments (OQ681438-OQ681443) were obtained. The S and M gene fragments were similar to the Shaanxi 84FLi strain and Sichuan SN7 strain. Phylogenetic analysis of S and M gene fragments showed that they all belonged to the hantaan virus-H5 subtype. Amino acid sequence analysis revealed that, compared with the hantaan virus vaccine strain 84FLi, the 74th amino acid encoded by eight S fragments was replaced by aspartamide with serine. Tryptophan was replaced by glycine at the 14th position of Gn region in XC2022047, and isoleucine was replaced by alanine at the 359 position of XC2022022 and XC2022024. Conclusion: The hantavirus carried by host animals in Henan Province from 2019 to 2022 belongs to the type Ⅰ (hantaan virus), and Apodemus agrarius is still the dominant host animal of the hantaan virus. Compared with the vaccine strains, amino acid sites are replaced in the immune epitopes of the S and M gene fragments.