Transboundary and Emerging Diseases

Gastrointestinal Vibrio parahaemolyticus infections, primarily associated with consumption of oysters, are emerging in Australia, where previously little was known about the disease and epidemiology. Following a multijurisdictional outbreak in 2021 and additional smaller outbreaks in subsequent years, an opportunistic whole genome sequencing study was undertaken to characterise human illness-causing strains in Australia. Through a multijurisdictional collaboration that bridged research, government, pathology service providers, aquaculture and clinicians, 676 V. parahaemolyticus genomes were contributed for analysis from human clinical, food, and environmental samples. We identified ST36, ST50 and ST417 as the dominant multi-locus sequence types causing gastrointestinal illness nationally. Phylogeographic contextualisation of Australian V. parahaemolyticus sequences within the global dataset indicates the Australian and New Zealand ST36 strain originated from a single point of introduction from the US Pacific-Northwest and is now circulating locally. In contrast, ST50 and ST417 appear to be endemic across Australia, with multiple lineages co-circulating. These findings establish a baseline for future outbreak investigations of V. parahaemolyticus in Australia and the consolidation of Australian data provides a critical platform for ongoing research, public health surveillance and risk mitigation.

Parasitic infections pose multifaceted threats to farmed fish, extending beyond direct pathogenicity to facilitate infections of bacteria, viruses, and microparasites. This synergistic interaction often leads to co-infections that significantly exacerbate disease outbreaks and mortality, presenting a severe challenge to aquaculture sustainability. Recently, a novel trypanosomiasis caused by the Trypanosoma carassii spectrum has emerged in cage-cultured Larimichthys crocea along the southeast coast of China, resulting in widespread prevalence and high mortality rates. Although this pathogen is hypothesized to originate from freshwater fish, its transmission route in marine environments has remained elusive. In this study, we investigated potential vectors and intermediate hosts of T. carassii spectrum, including leeches and monogenean in natural marine settings, and simulated transmission pathways using an established laboratory model involving T. carassii spectrum, Micropterus salmoides and the leech Poecilobdella manillensis. First, our field surveys in the coast of Ningde, Fujian Province, revealed a nearly 100% co-infection rate of T. carassii spectrum and the monogenean Neobenedenia girellae in diseased juvenile L. crocea. PCR analysis detected T. carassii spectrum traces in some N. girellae specimens, and subsequent experiments confirmed that N. girellae ingests the trypanosome while feeding on host blood. Furthermore, bacterial co-pathogens, such as Vibrio harveyi, were also detected within N. girellae. We also document two fatal leech infestations: Zeylanicobdella arugamensis in hybrid groupers (Epinephelus moara [female] X Epinephelus lanceolatus [male]) in Zhangpu, and Limnotrachelobdella okae in E. lanceolatus and E. fuscoguttatus in Raoping. These leeches tested negative for trypanosomes but carried pathogenic bacteria that co-infected the host fish; nonetheless, they are established vectors for trypanosome transmission. In a laboratory cohabitation model simulating T. carassii spectrum transmission, infected M. salmoides were housed with healthy conspecifics under three conditions: Group A (with the leech P. manillensis), Group B (no leeches), and Group C (no leeches, with physical separation between infected and healthy fish). After 14 days, blood smear microscopy and PCR analysis revealed infection rates in healthy fish of 58.33% in Group A, 40.00% in Group B, and 0% in Group C. Conclusively, T. carassii spectrum can be transmitted via leeches (with higher efficiency) and may also spread through direct contact under high-density aquaculture conditions, whereas N. girellae may act as an incidental vector, further research is warranted to clarify transmission dynamics in natural marine ecosystems. Additionally, our findings highlight the role of ectoparasites, including N. girellae and leeches, as potential reservoirs and vectors for bacterial pathogens of fish. In high-density intensive aquaculture, this vectorial capacity transforms parasites from primary pathogens into key drivers of polymicrobial disease outbreaks.

Introduction: Veterinary Professionals are at risk of contracting zoonoses, including potential emerging infections. Personal Protective Equipment (PPE) could reduce infection transmission risk, but use of it in the profession is low. Understanding Veterinary Professionals experiences with PPE could help identify facilitators and barriers, therefore informing a future strategy to improve usage. Methods: Two focus group discussion with veterinary nurses and two with veterinarians took place at a tertiary small animal teaching hospital. With an interpretivist epistemology, transcriptions were inductively coded and analysed using thematic analysis. Results: Veterinary Professionals frequently reported underusing PPE, despite significant zoonotic risk. Friction in interdisciplinary relationships negatively impacted veterinary professionals experiences with PPE: differing views on risk, policy and PPE, contrasting perceptions of each other, and challenges with communication impacted PPE decision-making. Barriers included an absence of initial recognition of risk, a staff culture of prioritising patient health over risk to self, friction in response to others PPE use or lack thereof, an overly complex policy, and a lack of cultural and institutional reaction to occupationally contracted zoonoses. Facilitators included effective inter and intradisciplinary communication and previous personal experience with serious zoonoses. Conclusion: Veterinary Professionals experiences with PPE, are shaped by social and professional factors, such as interdisciplinary friction, perceptions of self and others, of risk and policy. Recommendations are for the findings to be used locally to embed PPE use into everyday practice. At a national level, the United Kingdom Health Security Agency (UKHSA) should use the findings to evaluate current policies regarding PPE and zoonoses in veterinary practice and produce a simplified national guidance, in collaboration with veterinary professionals with lived experience. Further research into General Practice Veterinary Professionals experiences and the interdisciplinary social dynamics is recommended.

Bovine viral diarrhea virus (BVDV) remains an economically important pathogen of cattle despite widespread vaccination. A homozygous CD46-edited Gir heifer (Ginger) was previously shown to have significantly reduced susceptibility to BVDV. The edited allele contains an in-frame six amino acid substitution within the virus-binding domain of the BVDV entry receptor CD46, replacing residues G82QVLAL with A82LPTFS. Here, we investigated whether reduced BVDV susceptibility is maintained when the edited allele is inherited in the heterozygous state. Ginger was artificially inseminated with semen from an unedited Gir bull and produced a healthy heterozygous CD46-edited bull calf (Giraldo). Whole-genome sequencing confirmed the inheritance and structural integrity of Giraldo's edited allele. Compared with Ginger, Giraldo exhibited similarly reduced ex vivo BVDV susceptibility across primary fibroblasts, lymphocytes, and monocytes, despite inheriting a wild-type CD46 allele from the sire. Allele-specific CD46 RNA expression analysis demonstrated expression of both the edited and wild-type CD46 alleles. Thus, the reduced-susceptibility phenotype was not attributable to transcriptional silencing of the wild-type allele. Lentiviral complementation studies in CD46-knockout Madin-Darby bovine kidney (MDBK) cells further demonstrated that this wild-type CD46 allele was competent to support BVDV infection when expressed independently. Together, these findings indicate that the CD46 A82LPTFS allele can confer reduced BVDV susceptibility in the heterozygous state despite expression of a functional wild-type CD46 allele. This result suggests the potential to more rapidly disseminate reduced BVDV susceptibility through conventional breeding using homozygous CD46-edited sires.

Bartonella henselae is a zoonotic pathogen associated with cat-scratch disease. Although multilocus sequence typing (MLST) has been used for strain classification, its resolution for distinguishing between B. henselae isolates remains limited. We herein developed a B. henselae-specific core genome MLST (cgMLST) scheme based on whole-genome sequencing data and examined the genetic and phenotypic diversities of 80 strains derived from cats, humans, mongooses, and masked palm civets. Using the conventional MLST scheme, the 80 strains were classified into nine sequence types (STs), while cgMLST subdivided them into 72 cgSTs, demonstrating a marked improvement in discriminatory power. The cgMLST scheme comprised 1,183 core genes and showed high applicability across the 80 strains. A phylogenetic analysis revealed that ST1, which has been associated with cat-scratch disease, was further subdivided into three major clusters and two singletons, indicating high genetic heterogeneity within this ST. We also found that the bafA subtypes clustered in a manner that was largely consistent with the cgMLST-based phylogenetic structure, suggesting a close relationship between bafA variations and the genomic background of B. henselae strains. In a human umbilical vein endothelial cell proliferation assay, strains belonging to distinct cgSTs exhibited strain-dependent differences in proliferative capacity, which were associated with the bafA subtype classification. Some strains induced focal cell fragmentation and a reduced cell density at a high multiplicity of infection, indicating strain-dependent differences in endothelial cell injury. Collectively, the present results establish a high-resolution cgMLST framework for B. henselae and demonstrate that genetically distinct strains have diverse endothelial cell phenotypes.

Leptospirosis is an infectious neglected zoonotic disease caused by pathogenic bacteria of the genus Leptospira. The genus comprises 43 pathogenic species, divided into two clades (P1 and P2), with the potential to cause disease on animals and humans. Despite the major impact of this disease on animal and human health, few quantitative real-time polymerase chain reaction (qPCR) assays have been validated to specifically detect all pathogenic Leptospira species, thwarting diagnosis and epidemiological studies. The gene encoding LipL32, the major leptospiral outer membrane protein, discriminates pathogenic P1 species from P2 and saprophytic. However, with the recent discovery of new species, the current lipL32-based qPCR assay cannot detect all classified P1 species. Furthermore, there are no currently validated molecular methods able to differentiate the presence of P1 and P2 species on clinical samples. Previous analyses have shown that the 23S ribosomal RNA gene displays considerable conservation in P1 and P2 species but sequence divergence in saprophytic species, a promising target for PCR-based detection and discrimination of those two clades. This study optimized and validated an improved lipL32- and 23S-based TaqMan qPCR assay using human and animal clinical samples. These newly optimized and developed assays resulted in a lower limit of detection and increased diagnostic sensitivity, resulting in the detection of all pathogenic species of the genus Leptospira currently described. These assays will improve the detection of leptospires from clinical and environmental samples, providing a valuable epidemiological and clinical tool to support One Health research on this important emerging disease.

The recent large-scale circulation of High Pathogenicity Avian Influenza (HP AI) viruses H5Nx of clade 2.3.4.4b has been responsible for massive die-offs in wild species, notably in long-lived seabirds, with unknown implications for the immunity of surviving individuals. In the North Atlantic, northern gannet colonies were heavily affected in 2022, with more than 40% mortality observed among breeding adults and some surviving individuals developing dark irises. Using samples collected in 2023 and 2024 on Rouzic colony (France), we report persistent individual anti-AI antibody levels and seroneutralisation titres, with most of the immune individuals showing dark irises. A modelling approach further stressed the importance of long-lasting immunity in such species by showing that the proportion of individuals which kept their immunity between years strongly limited decreases in population size in case of repeated outbreaks. Overall, our results highlight the existence and importance of long-lasting immunity in long-lived species for population persistence.

Viruses have diverse life history strategies driven by variation in traits such as infectivity, transmission mode, and length and severity of infection that affect their epidemiology and evolution. While well documented among different species, life history and phenotypic variation among variants of the same virus species are less well understood. Foot-and-mouth-disease-virus (FMDV) is an ungulate-infecting picornavirus endemic to many regions, including Sub-Saharan Africa, where it circulates between wildlife and livestock in several serotypes. Recent work suggested that FMDV variants from the three Southern-African Territories serotypes exhibit different life history strategies, with these dynamics potentially causing distinct signatures in viral evolutionary rate, transmission among host species, and movement among regions. To investigate whether any effects of predicted effects occurred in natural settings, and whether these differences were shared with other strains within each serotype, this study used 716 published FMDV sequences (approximately 430bp) from 3 serotypes (SAT1, SAT2, and SAT3) to measure and compare evolutionary rates and transmission between regions and host types in Southern Africa. SAT1 had a slower rate of evolution consistent with a predicted more chronic infection strategy, and SAT2 had higher variability in evolutionary rates and some evidence of transmission from livestock to wildlife, suggesting livestock may play a part in persistence. SAT3 showed an expected intermediate phenotype but was challenging to validate due to small sample size. All SATs showed similar levels of transmission between regions. These results suggest that SAT1, SAT2, and SAT3 exhibit different transmission dynamics and evolutionary signatures, consistent with different life history strategies observed in their representative strains, such as more latency or a multi-host maintenance community.

Objectives: To estimate early growth rate, back-calculate transmission onset, and characterise the case-fatality trajectory of the 2026 Bundibugyo virus disease (BDBV) outbreak in the Democratic Republic of the Congo, the largest recorded BDBV outbreak to date. Design or methods: We analysed a corrected daily surveillance series (65 observations, 14 May to 27 July 2026) using non-linear least-squares regression and a Bayesian Poisson growth model fitted by Markov chain Monte Carlo, with five sensitivity analyses. Results: Early confirmed cases grew at 0.1261 per day (95% CI 0.0885-0.1636), a doubling time of 5.50 days (4.24-7.83), three-fold faster than previous BDBV outbreaks (15-18 days). Bayesian back-calculation placed transmission onset on 19 April 2026 (95% highest-density interval 9-27 April), 16 days before the WHO alert and 25 days before laboratory confirmation. Confirmed case-fatality ratio rose from 12.1% to 44.3%; a higher ratio among suspected than confirmed cases on 21 May (23.6% vs 10.8%; p=0.0080) supported progressive reclassification rather than increasing virulence. Conclusions: Rapid BDBV growth leaves little time for outbreak-triggered mobilisation. Sentinel alerts based on unexplained healthcare-worker death clusters, together with pre-positioned surveillance, diagnostic, and response capacity, could reduce avoidable amplification before confirmation.

BackgroundEscherichia coli contamination of chicken eggs is an important food-safety concern, while antimicrobial-resistant E. coli may contribute to the dissemination of antimicrobial resistance through the food chain. However, information on egg-associated E. coli and its antimicrobial susceptibility in Natore District, Bangladesh, is limited. ObjectivesThis study aimed to determine the prevalence of E. coli in chicken eggs collected from commercial farms, markets and indigenous/backyard flocks in Natore District, identify the isolates based on cultural, morphological and biochemical characteristics, and assess their antimicrobial susceptibility. Materials and MethodsA total of 84 egg-shell swab samples, comprising 28 samples each from commercial farms, markets and indigenous chicken flocks, were collected from seven upazillas of Natore District between January and June 2023. Samples were cultured on selective and differential media, and presumptive isolates were confirmed by Gram staining, motility and biochemical tests. Antimicrobial susceptibility was determined using the Kirby-Bauer disc-diffusion method against seven antimicrobial agents. ResultsE. coli was detected in 56/84 (66.67%) egg samples. Prevalence was highest in indigenous eggs (22/28, 78.57%), followed by farm eggs (18/28, 64.28%) and market eggs (16/28, 57.14%). Among 22 confirmed isolates tested for antimicrobial susceptibility, resistance was highest to neomycin (90.91%) and erythromycin (86.36%), followed by oxytetracycline (77.27%), amoxicillin (68.18%), ciprofloxacin (63.63%), levofloxacin (59.09%) and doxycycline (36.36%). No isolate was sensitive to neomycin or erythromycin. ConclusionThe high prevalence of E. coli and substantial antimicrobial resistance among egg-associated isolates indicate an important food-safety and public-health concern. Improved hygienic egg handling, prudent antimicrobial use and continued antimicrobial-resistance surveillance are warranted throughout the poultry production and marketing chain.

Botulinum neurotoxins (BoNTs) comprise a highly diverse group of seven serotypes (from A-G) and over 40 subtypes worldwide. Previous primer- and probe-based nucleic acid amplification tests (NAATs) for detection of BoNT encoding genes are challenged by high levels of nucleotide polymorphism both across and within subtypes. In this study, multiple BoNT gene sequences were aligned to identify highly conserved regions for the design of new primers that enable the detection of all seven serotypes under the same conditions. Specific primer sets were designed and validated using in silico, conventional and real-time PCR with constructed plasmids carrying the target fragments and spiked food matrices. The established procedure achieved highly specific and sensitive detection of BoNT serotypes A-G with sensitivity of 10 copies/reaction and a total turnaround time of approximately 1.5 hours. The procedure also eliminated the carryover PCR product by using uracil-N-glycosylase in combination with dUTP in the assay reaction mix. This study provides an alternative NAAT with higher coverage and compliments the traditional mouse bioassays in enhancing global botulism surveillance capabilities.

Leptospirosis is a widespread zoonotic infection and a growing public health concern in tropical, resource-limited settings, yet remains underrecognized and underreported where diagnostic and surveillance infrastructure is limited. We conducted an analytical cross-sectional study of national surveillance data from the Dominican Republic (2012-June 2026), integrating geospatial meteorological data to characterize disease burden, trends, seasonality, and clinical risk factors. Of 8,425 records, 5,412 met case-definition criteria (3,441 suspected, 1,448 probable, 523 confirmed), yielding a cumulative incidence of 3.55 per 100,000 person-years (2012-2025). Laboratory confirmation rose markedly, from 9.7% overall to half of 2025 cases and over half in 2026. Overall incidence remained stable across all years (p = 0.15), though with three distinct periods: declining infection pre-COVID, low infection during COVID, and increasing infection post-COVID. Cases clustered in the rainy/hurricane season (61.1%, May-November; p< 0.001), with a marginal rainfall correlation (r= 0.553, p= 0.062). Rural provinces bore disproportionate risk, led by Hermanas Mirabal (16.43/100,000 person-years), while large urban and coastal provinces had rates 80% lower. Men had 2.73-fold higher incidence than women (95% CI 2.56-2.90), peaking at younger ages 10-29. Comorbidity was the strongest predictor of complications (OR 2.84, 95% CI 2.01-4.02, p< 0.001). Limited diagnostic confirmation remains the central obstacle to characterizing leptospirosis burden in the Dominican Republic, with confirmation rates exceeding 40% only from 2023 onward. This first multi-decade national analysis identifies high-risk provinces, demographic groups, and seasonal windows for targeted surveillance, highlighting expanded diagnostic capacity as a priority for burden estimation and case management.

Existing molecular diagnostic approaches for notifiable avian diseases (NADs) involve a suite of PCR assays that enable both generic detection, and where positive, subtyping of both avian influenza virus (AIV) and Newcastle disease virus (NDV). Novel rapid and direct diagnostic assays for the detection of AIV and NDV were developed and evaluated using unprocessed cloacal (C) and oropharyngeal (OP) poultry swab material. Both assays employ a closed tube direct real-time reverse transcription polymerase chain reaction (RRT-PCR) approach in which viral lysis is achieved by heat treatment and a dedicated PCR compatible buffer, followed by detection using a RRT-PCR approach. Primer and probe sets were designed using globally circulating AIV and NDV sequences collected over the preceding five years, rather than region-specific sequence datasets, so that the assays detect all circulating genotypes. Analytical performance assessment demonstrated that both assays were highly sensitive and specific, successfully detecting all unextracted target antigens without cross reactivity to a panel of other common poultry pathogens. For each assay, viral lysis and amplification were achieved directly from samples at single digit genome copy numbers. Furthermore, low levels of viral RNA could be reliably detected in the presence of C and OP matrix material, providing proof-of-concept for direct detection of these economically significant avian pathogens in a field setting. Additional use case scenarios, including pooled sample screening and combined C/OP testing from individual birds, were also explored. These findings establish a foundation for ongoing studies incorporating paired-sample testing against validated laboratory reference assays.

An uncontrolled and rapidly growing outbreak of Bundibugyo virus (BDBV) is currently gripping the Democratic Republic of the Congo and threatening health security across Central Africa. There are no available BDBV-specific vaccines, although emerging evidence suggests that the Ebola virus-specific vaccine, rVSV-EBOV (also known by its tradename ERVEBO), may offer cross-protective immunity. To directly address this question, we evaluated the efficacy of rVSV-EBOV in the uniformly lethal ferret model of BDBV infection. All vaccinated animals survived BDBV challenge and exhibited minimal clinical signs of infection, presumably as a result of a moderate--but protective--humoral immune response. These findings provide critical evidence further supporting the cross-protective efficacy of rVSV-EBOV, and they suggest a potential role for this vaccine in mitigating the ongoing BDBV outbreak.

The current outbreak of Bundibugyo virus (BDBV) in Africa is a global public health concern particularly as there are no licensed medical countermeasures (MCM). Well characterized animal models that accurately replicate human BDBV infection are needed to develop effective MCM. We exposed 21 cynomolgus monkeys (CM) to BDBV to examine the progression and natural history of BDBV disease (BVD). BVD was more protracted than reported for Ebola and Sudan infection in CM with a lower lethality rate of 67% consistent with lower human BVD mortality rates. IHC and spatial proteomics identified CD209+, CD68+, and/or HLA-DR+ macrophages and dendritic cells as early targets of BDBV. These infected cells frequently colocalized with fibrin and infiltrating MPO+ neutrophils and S100A9+ myeloid-derived suppressor cells, consistent with the development of an active inflammatory response and early coagulopathy. Transcriptomic and proteomic analyses of the circulating immune response correspondingly reflected a cytokine-driven hyperinflammatory state in CM that succumbed to disease. Surviving animals resolved systemic inflammation by the study endpoint; however, BDBV antigen was identified in immune privileged tissues with lesion-associated inflammation aligning with known post-Ebola sequela in humans. This data should assist in identifying weaknesses in the disease course that can be exploited to develop new MCM.

Antimicrobial resistance (AMR) is one of the greatest challenges within the One Health continuum. Exploring transmission routes between health domains and determining their driving forces are key priorities for future research. This effort can be effectively supported by landscape epidemiology, a field of science that integrates methods from landscape ecology and epidemiology to unravel the complex interdependencies behind disease transmission. This exploratory study aimed to demonstrate that landscape diversity and the degree of hemeroby (anthropogenic impact) correlate with the composition of bacterial communities and their AMR profiles. To test this hypothesis, submandibular lymph nodes from Cervidae and Suidae were collected to detect Staphylococcus and Mammaliicoccus bacteria and characterise their AMR features using selective culture and the VITEK 2 Compact automated system. As a result, the bacterial community in the more natural landscape was more diverse, characterised by the dominance of Mammaliicoccus sciuri and pan-susceptible isolates of Staphylococcus hyicus, and it displayed a low-level, heterogeneous AMR profile. Within the more hemerobic landscape, the bacterial community was characterised by the dominance of Staphylococcus epidermidis, a human-adapted species, and the AMR profile showed signs of higher antimicrobial pressure from both public health and veterinary origins. Although this study was based on only two study sites and was therefore not suitable for drawing definite conclusions, the findings suggest that human impact manifests itself in both bacterial and AMR profiles. A high prevalence of mammaliicocci and a heterogeneous AMR profile appeared to be indicators of naturalness. Conversely, the dominance of a human-adapted bacterial species and the accumulation of AMR features characteristic of medical environments likely indicate higher degrees of hemeroby.

Ticks are obligate hematophagous arthropods and feed exclusively on blood. As blood is nutrient-poor, ticks rely on bacterial endosymbionts to synthesise nutrients, yet the diversity and functional roles of these symbionts in Australian ticks remain largely uncharacterised. This is critical to address as these ticks are of high medical importance in Australia. In this study, shotgun metagenomic sequencing was performed on Bothriocroton concolor, Bothriocroton hydrosauri, Haemaphysalis longicornis and Ixodes holocyclus, enabling the recovery of six complete or partial metagenome-assembled genomes (MAGs). These comprised Coxiella-like endosymbionts (CLE), a facultative Rickettsia symbiont, and two Midichloria mitochondrii strains (Ixholo1 and Ixholo2). Functional annotation of these taxon-specific symbionts revealed the absence of virulence factors and the presence of B-vitamin and/or heme biosynthesis genes, indicative of nutritional mutualism, which is essential for tick hematophagy. The CLEs additionally harbour genes of the shikimate pathway, which modulate blood feeding in ticks by regulating serotonin biosynthesis. Furthermore, functional annotation and pangenomic analysis of Midichloria spp. found evidence that the genus may encompass multiple species, as well as the retention of genes potentially associated with an intramitochondrial lifestyle in M. mitochondrii Ixholo2. Tick microbiomes are dominated by non-pathogenic microorganisms, which are often overshadowed by pathogens. These include the endosymbionts, which can influence host biology and pathogen transmission, and are fundamental for the development of diagnostic tools and taxon-specific tick biocontrols.

Background: Retail red meat may act as a source of foodborne pathogens, antimicrobial resistant bacteria, and antibiotic residues, posing a significant public health concern in Bangladesh. Objectives: This study aimed to isolate and identify major bacterial pathogens from retail red meat, determine their antimicrobial susceptibility patterns, assess the prevalence of antibiotic resistant bacteria, and detect antibiotic residues in meat samples. Methods: A cross-sectional study was conducted from January to June 2019 using 60 retail red meat samples (20 cattle, 20 goat, and 20 buffalo) collected from Rajshahi and Naogaon districts. Bacterial isolates were identified using standard cultural, morphological, staining, and biochemical techniques. Antimicrobial susceptibility was evaluated by the Kirby Bauer disc diffusion method according to CLSI guidelines. Antibiotic residues were screened in 15 representative samples using thin layer chromatography (TLC). Results: Overall prevalence of Escherichia coli, Salmonella spp., and Staphylococcus aureus was 10.0%, 13.3%, and 28.3%, respectively. E. coli showed complete resistance to penicillin (100%) and high resistance to amoxicillin (83.3%), while remaining highly susceptible to ciprofloxacin (83.3%) and gentamicin (66.7%). Salmonella spp. exhibited highest resistance to penicillin (87.5%) and tetracycline (75.0%), whereas gentamicin (87.5%) and ciprofloxacin (75.0%) remained the most effective agents. S. aureus demonstrated marked resistance to penicillin (94.1%), ampicillin (58.8%), tetracycline (47.1%), and amoxicillin (47.1%), but high susceptibility to gentamicin (88.2%) and ceftriaxone (70.6%). TLC detected ciprofloxacin and oxytetracycline residues in one cattle meat sample each (6.7%). Conclusions: Retail red meat marketed in the study areas harbored multidrug-resistant bacterial pathogens and detectable antibiotic residues, highlighting potential risks to food safety and public health. Continuous surveillance, prudent antimicrobial use, improved slaughterhouse hygiene, and strict compliance with antibiotic withdrawal periods are essential to minimize antimicrobial resistance and residue contamination.

Bats harbor a diversity of viruses, some of which have the potential to impact human and livestock health. Caves in Eastern Uganda are commonly inhabited by bats in the genera Rhinolophus, Hipposideros, Myonycteris, and others. Human encroachment into these caves for shelter, hunting, mineral harvesting, and tourism poses a risk of exposure to infectious agents these bats may carry, yet little is known about the viruses present in these bats. From 2021 - 2023, 635 unique bats were captured in caves by mist net, with 69 bats resampled over the study for a total of 706 sampling instances. A total of 1,394 oral and rectal swabs were collected non-destructively and screened using molecular techniques for coronaviruses, paramyxoviruses, rhabdoviruses, flaviviruses, and filoviruses. Of these samples, 399 (56.5%) were collected during the rainy season and 307 (43.5%) during the dry season. Coronavirus RNA was detected in 59/706 (8.36%) of samples from Rhinolophus spp. (n = 35), Hipposideros caffer (n = 12), Myonycteris angolensis (n = 6), and Miniopterus spp. (n = 6). Six bats (0.85%) were positive for paramyxoviruses. Finally, (3 H. caffer, 1 M. angolensis, 1 Rhinolophus spp. and 1 Nycteris thebaica) 3 Rhinolophus bats were positive for rhabdoviruses (0.42%, all Rhinolophus spp.). No samples were positive for filovirus or flavivirus RNA. This project has generated novel data on the association of bat species and different viral strains present in these bats, advancing our knowledge of viral ecology and spillover risk at the human/bat interface.

Background Visceral leishmaniasis (VL), caused by Leishmania donovani (LD), is increasingly associated with the insect-restricted trypanosomatid Leptomonas seymouri (LS), which harbours the RNA virus Leptomonas seymouri narna-like virus 1 (Lepsey NLV1). Our recent study demonstrated that LS co-infection with LD enhances survival of murine (RAW 264.7) and mammalian (THP-1) macrophages and augments LD and LS persistence compared to LD or LS mono-infection in vitro. However, the in vivo fate of LS and its viral endosymbiont during chronic VL remains poorly understood. This study investigated the long-term dynamics of parasite persistence, tissue dissemination and viral maintenance during experimental mono- and co-infection. Methods and Findings BALB/c mice were infected with LD, Lepsey NLV1-positive LS, virus-positive AG83 isolate, or LD: LS co-infections (2:1, 5:1 and 10:1) and monitored for up to seven months. Parasite burden, species composition and viral load were quantified using ITS1 qPCR, densitometry, nested RT-PCR and qRT-PCR, supported by microscopy and immunofluorescence assay. LS established productive visceral infection independently, with parasite burdens exceeding the infecting inoculum, indicating active in vivo replication. Co-infection, particularly at a 10:1 LD: LS ratio, promoted the greatest long-term parasite persistence in visceral organs. Temporal analysis revealed early predominance of LS followed by progressive recovery of LD during chronic infection. Lepsey NLV1 was detected in visceral organs and blood for at least up to five months. Morphological analyses demonstrated intracellular LS amastigote-like forms in murine macrophages and transformation of splenic parasites into promastigotes, confirming parasite viability within mammalian tissues. Conclusions These findings demonstrate sustained visceral persistence of Lepsey NLV1-positive LS in mice and identify dynamic host-parasite-virus interactions that reshape infection during chronic co-infection. This work challenges the conventional view of VL as a strictly mono-parasitic disease and highlights a previously underappreciated tripartite interaction with potential implications of LS and its virus endosymbiont for VL pathogenesis.