Zoonotic Dis., Volume 6, Issue 3 (September 2026) – 11 articles

Wastewater treatment plants are important interfaces for the persistence and environmental dissemination of antibiotic-resistant bacteria, yet quantitative culture-based studies comparing treated effluent with paired upstream and downstream receiving waters across multiple sentinel organisms remain limited. This study quantified antibiotic-resistant Escherichia coli, Enterococcus, and Pseudomonas aeruginosa in treated municipal effluent and receiving river waters in northeast Tennessee. Grab samples were collected monthly from March through November 2025 at the following three locations: final chlorinated effluent, upstream water, and downstream water. Target organisms included cefotaxime-resistant E. coli, erythromycin- and vancomycin-resistant Enterococcus, and imipenem- and ceftazidime-resistant P. aeruginosa, measured on selective media with paired no-antibiotic plates. Antibiotic-resistant colony counts were analyzed using negative binomial regression with adjustment for sampling month and offsets for plated volume and confirmation-adjusted paired no-antibiotic counts. Among 114 samples, cefotaxime-resistant E. coli counts were significantly higher upstream than downstream, whereas effluent did not differ significantly from downstream. Vancomycin-resistant Enterococcus counts were significantly higher upstream and in effluent than downstream. Imipenem-resistant P. aeruginosa counts were highest in effluent, whereas P. aeruginosa ceftazidime-resistant counts remained low across sites. These findings indicate that antibiotic-resistant bacterial burdens were organism- and antibiotic-specific and did not show a uniform downstream enrichment pattern attributable to treated effluent alone. Full article

Historically, mpox was thought to be a geographically constrained ‘disease of poverty,’ leading to decades of neglect by global health actors. Waning population immunity from the cessation of smallpox vaccination and prolonged scientific neglect created conditions that enabled the monkeypox virus (MPXV) to adapt cryptically. This ultimately contributed to the emergence of unprecedented global public health crises. This review aims to systematically trace the history, epidemiology, genomic evolution, and reservoir ecology of mpox in West Africa from 1970 to 2025. Following PRISMA guidelines, 110 articles met the inclusion criteria and were synthesized to map the virus’s trajectory. For nearly four decades, an “Era of Silence” (1970–2016) masked the silent enzootic circulation of MPXV within West African wildlife, primarily rodents and small mammals. This epidemiological quiescence ended with the 2017 re-emergence in Nigeria, which signaled a fundamental paradigm shift. The disease profile transitioned from sporadic, rural paediatric infections to sustained, urban and secondary transmission among young adult males. This shift was often associated with sexual networks, especially among men who have sex with men, and was characterized by novel clinical presentations, including genital and perianal lesions. Genomic analyses revealed that clade II diverged from clade I approximately 3500 years ago and is uniquely defined by the deletion of virulence factors, such as the complement-binding protein. Importantly, the clade IIb lineage, which triggered the 2022 global outbreak, exhibits accelerated microevolution consistent with APOBEC3-mediated hypermutation. This host-driven mutational signature provides genomic evidence supporting the hypothesis that clade IIb circulated cryptically within human-to-human transmission chains in West Africa as early as 2014. Ecologically, while no definitive reservoir has yet been identified, evidence suggests diverse rodents and an expanding host range. The transformation of mpox from a rare zoonosis to a global threat underscores the severe consequences of delayed intervention, demanding robust, integrated “One Health” surveillance. Full article

Background/Objectives: Melioidosis is an environmentally acquired infection caused by Burkholderia pseudomallei (B. pseudomallei). Although historically framed as a tropical disease, evidence indicates that recognized risk can extend beyond classical endemic regions. This narrative review synthesized Digital Object Identifier (DOI)-verified evidence on environmental persistence, climate-sensitive risk, geographic emergence, and One Health preparedness. Methods: Structured narrative searches of PubMed/Medical Literature Analysis and Retrieval System Online (MEDLINE), Europe PubMed Central (Europe PMC), Crossref, and publisher records were conducted for literature available up to 19 June 2026. Forty-four DOI-verified sources were retained. Evidence categories were derived inductively by inferential function during thematic synthesis and used as a qualitative interpretive framework, not as a validated quantitative risk score. Results: B. pseudomallei persists in soil and water, survives nutrient limitation, and clusters in environmental microfoci, but the interpretive value of detection depends on viability, exposure context, and diagnostic endpoint. Rainfall, humidity, flooding, and cyclones are associated with incidence, severity, or mobilization in several settings, supporting climate-sensitive risk rather than uniform geographic spread. Case-based evidence is strongest when it separates importation, local acquisition, environmental establishment, source attribution, and animal sentinel signals. Human risk depends on exposure route, host susceptibility, diagnostic recognition, and access to prolonged antimicrobial management, whereas animal evidence is best interpreted as sentinel or common-exposure evidence unless reservoir or direct-transmission data are available. Conclusions: Melioidosis beyond the tropics requires graded evidence interpretation because environmental detection, modeled suitability, animal signals, and human cases support different levels of geographic and One Health inference; this approach links early signals to surveillance while reserving higher-confidence claims for convergent evidence. Full article

Dengue virus (DENV) remains a major global public health challenge, driven by the expanding distribution of Aedes vectors, rapid urbanization, and increasing climate variability. This review aimed to synthesize current evidence on dengue transmission dynamics, immunopathogenesis, molecular epidemiology, diagnostic and therapeutic advances, vaccine development, and the influence of climatic factors on disease patterns. A comprehensive search of major electronic databases was conducted to identify relevant literature, followed by a qualitative synthesis of the evidence. The evidence highlights complex transmission cycles involving Aedes aegypti and Aedes albopictus, with transmission strongly influenced by temperature, humidity, rainfall, and extreme climate events. Advances in immunopathogenesis research have improved understanding of mechanisms associated with severe disease, including antibody-dependent enhancement and dysregulated inflammatory responses. Diagnostic innovations, such as reverse transcription polymerase chain reaction (RT-PCR), NS1 antigen detection, and point-of-care technologies, have enhanced case identification, while prevention strategies increasingly incorporate integrated vector management, digital surveillance systems, and emerging vaccines. Integrating epidemiological, molecular, and climatic information may strengthen early warning systems, improve outbreak prediction, and support more effective dengue prevention and control strategies. Full article

Severe malaria remains a global public health challenge, and acute kidney injury (AKI) is a frequent and potentially lethal complication. Variability in diagnostic criteria has limited estimation of the reported burden, particularly in pediatric populations and endemic settings. This study synthesized evidence on the reported prevalence of AKI in patients with severe malaria, stratified by age group, geographic region, Plasmodium species, and diagnostic definition. A systematic review and meta-analysis was conducted following PRISMA guidelines. Six electronic databases (PubMed/MEDLINE, Scopus, Web of Science, EMBASE, LILACS, and SciELO) were searched from 1 January 2000 to 30 March 2026, complemented by manual reference screening. Observational studies in patients with severe malaria that reported AKI prevalence according to defined criteria were included. A random-effects meta-analysis of proportions was performed with subgroup analyses and meta-regression. Eleven studies including 3113 patients were included. The pooled reported prevalence of AKI was 39.6% (95% CI: 29.9–49.6%) in children and 33.4% (95% CI: 13.3–57.0%) in adult or adult-classified cohorts, with substantial heterogeneity (I² >95%). Reported AKI prevalence increased across publication years in pediatric studies (ρ = 0.880, p < 0.01), a pattern likely reflecting greater diagnostic sensitivity and clinical awareness after adoption of Kidney Disease: Improving Global Outcomes (KDIGO) criteria rather than a proven biological increase. African studies reported higher prevalences (43.5%) than Asian studies (18.3%). AKI is frequently reported in severe malaria, but pooled estimates should be interpreted cautiously because heterogeneity was substantial and eligible studies were geographically concentrated. These findings support standardized renal assessment in severe malaria management and harmonized AKI definitions in future studies. Full article

Crimean–Congo hemorrhagic fever (CCHF) is a severe tick-borne zoonotic disease associated with high case fatality rates in humans and represents a significant public health threat in endemic areas of Kosovo. However, data on viral circulation in ticks in non-endemic regions remain limited. CCHF is caused by Orthonairovirus haemorrhagiae, formerly known as the Crimean–Congo hemorrhagic fever virus (CCHFV). In the present study, 745 ticks were collected from domestic animals and the environment throughout the years 2017–2019 in seven locations of non-endemic regions in the eastern part of Kosovo, respectively Prishtina, Gjilan and Kamenica municipalities. The ticks after species identification were analyzed using RT-PCR for detection of viral RNA of CCHFV. Seven ticks (0.94%) tested positive, including six Rhipicephalus bursa ticks, three of them collected from grazing cattle and sheep in the village Hajvali (Prishtina municipality) and three others in the village Busavat (Kamenica municipality) from grazing cattle, while one positive sample was detected in a Hyalomma marginatum tick collected from a grazing dairy cow in Bresalc village (Gjilan municipality). The virus detected in Rh. bursa is considered to be consistent with the Aigia virus, formerly classified as CCHFV Clade VI/Europe 2 or the AP92-like lineage, which has generally been associated with a lower pathogenic potential and the absence of reported human cases in these areas. The first reported human CCHF case in a non-endemic area occurred in the Bresalc locality (Gjilan Municipality) in June 2018 in a dairy farmer. This occurrence coincided with the detection of Orthonairovirus haemorrhagiae RNA in one Hyalomma marginatum tick among 36 sampled ticks collected from the same farm, following clinical and laboratory confirmation of CCHF in infected patients. Consequently, this finding indicated the circulation of CCHFV in this area. These results demonstrated active circulation of CCHFV in tick populations in regions previously considered non-endemic and highlighted a potential public health risk associated with pathogenic strains. Genomic and tick surveillance, combined with targeted vector control measures and public awareness, are essential for reducing CCHFV transmission and preventing human infections. Full article

Q fever, caused by Coxiella burnetii, is a globally distributed zoonosis that remains substantially underdiagnosed, despite increasing reports of human and animal infections across Europe. Within the Zoonoses Working Group of the Trás-os-Montes and Alto Douro Academic Clinical Center (CAC TMAD), which integrates human and animal health professionals, an apparent discrepancy emerged. Although no official human notifications had been recorded in Trás-os-Montes in recent years, three clinical cases, at hospital level, were identified in the Bragança district between 2021 and 2024. This unexpected finding prompted an evaluation of local veterinary awareness of Q fever in livestock, given that no cases had ever been reported. A structured, simple questionnaire was provided to all livestock veterinarians in the district, achieving an 88.5% response rate (23/26). Among respondents, 43.5% (10/23) reported laboratory-confirmed C. burnetii-positive results in clinically suspected livestock (both serology and PCR). All reported clinical cases occurred in small ruminants, with abortion as the predominant clinical manifestation. These results provide local evidence of active C. burnetii circulation in both humans and livestock in Bragança, suggesting potential underreporting. This gap supports the need to strengthen clinical recognition and reporting practices among medical and veterinary professionals, firmly embedded within a One Health framework. Full article

Ectoparasite-borne infections have become a global public health problem. This study investigated the diversity of fleas and mites associated with wild rodents in the northeastern region of Argentine Patagonia and analyzed the molecular presence of Rickettsia and Bartonella within these arthropods. Research was conducted in the Monte Desierto biome, focusing on areas where wildlife, livestock, and human activities overlap. Ectoparasites (n = 32) were collected from captured rodents and subjected to PCR amplification and phylogenetic analysis using gltA and rpoB for Bartonella and OmpA, OmpB and gltA for Rickettsia. Bartonella DNA was detected in all studied ectoparasites, with the obtained gltA and rpoB sequences showing 100% and 99% identity, respectively, to reference sequences of Bartonella sp. closely related to Bartonella quintana, whereas no Rickettsia DNA was detected. Specifically, the pathogen was identified in four flea species (Craneopsylla minerva wolffhuegeli, Neotyphloceras crackensis, Polygenis rimatus, and Ectinorus sp.) and the mite Gigantolaelaps wolffsohni, while Rickettsia was not detected in any samples. These findings constitute the first report of Bartonella sp. closely related to B. quintana in this geographical region as well as the first detection of the bacterium in these specific flea and mite species in South America. Our results suggest an active wild cycle of Bartonella sp., emphasizing the importance of the One Health approach in monitoring emerging infectious diseases. Full article

Rat hepatitis E virus (rHEV) is an emerging zoonotic pathogen, increasingly detected in human, animal, and environmental samples globally. Although rHEV shares the same subfamily as human hepatitis E virus (HEV; Paslahepevirus balayani), which is endemic across Africa, little is known about rHEV ecology on the continent beyond an isolated travel-related case linked to the Democratic Republic of Congo and Gabon. As a rodent-borne virus, rHEV poses a public health risk due to the widespread presence of the synanthropic reservoir Rattus norvegicus. Limited data on hepatitis of unknown origin further emphasise the need for active surveillance to understand the distribution, epidemiology, and impact of rHEV on human health. This review summarises our current knowledge on the global distribution of rHEV in humans, animals, and the environment, highlighting the importance of ongoing surveillance through the One Health Approach. Monitoring the virus in countries such as Nigeria, a country with a significant pig population and documented circulation of hepatitis E virus (HEV), could improve healthcare for immunocompromised and at-risk populations. Furthermore, the viral evolution may facilitate host adaptation and transmission, thereby complicating control efforts. These factors underscore the necessity for targeted research and intervention strategies to address the emerging threat of rHEV effectively. Full article

Leptospirosis is a climate-sensitive zoonosis whose transmission is associated with environmental and hydrological conditions, particularly in tropical regions. This ecological time-series study investigated the associations between leptospirosis incidence and climatic, hydrological, and structural variables in the Brazilian Amazon from 2005 to 2024 using annually aggregated data. Annual confirmed cases were obtained from national surveillance systems, while climatic and extreme-event data were derived from official meteorological and disaster databases. Associations were evaluated using generalized additive models with a negative binomial distribution. Leptospirosis incidence exhibited marked interannual variability without a significant temporal trend. Flooding events were significantly associated with increased incidence, whereas mean temperature and accumulated precipitation showed no independent association. Lagged precipitation emerged as a significant predictor, suggesting that environmental conditions associated with transmission may persist beyond the initial exposure period. Heavy rainfall events increased over time but were not associated with incidence. Sanitation coverage improved consistently but did not explain temporal variation in disease occurrence. These findings suggest that hydrological extremes and delayed precipitation patterns may serve as useful indicators of leptospirosis dynamics in the Brazilian Amazon. Incorporating these indicators into surveillance systems may improve the characterization of leptospirosis patterns in tropical regions. Full article

Mpox is a zoonotic infectious disease caused by the species Orthopoxvirus monkeypox (MPV), which is becoming an increasing public health concern. While human-to-human transmission of the virus is well established, the role of domestic animals in MPV infection remains poorly understood. Investigating how the virus is transmitted among humans, dogs, and cats can improve our understanding of the disease’s pathogenesis and help develop strategies to limit its dissemination during future outbreaks. In this study samples were collected from four domestic animals (three dogs and one cat) in May 2023. These animals lived in a household where a human mpox case had been confirmed by PCR in March 2023, approximately 2 months before animal sampling. A plaque reduction neutralization test (PRNT) using vaccinia virus was performed to detect anti-orthopoxvirus (OPV) neutralizing antibodies (nAbs). Our data demonstrated that anti-OPV nAbs were present in samples obtained from three dogs and one cat with neutralization titers ranging from 1:5 to 1:20. These results indicate that the domestic animals were exposed to OPVs after contact with an individual with confirmed mpox, suggesting possible human-to-animal transmission within a household. Nevertheless, due to the cross-reactive immune response among OPVs, and the endemic circulation of vaccinia virus in Brazil, it is not possible to determine the specific viral species based solely on PRNT results. Therefore, these serological findings should be interpreted as evidence of OPV’s exposure rather than confirmed MPV infection. Full article