Zoonotic Diseases

Active and passive surveillance, followed by gene sequencing, continue to be used to identify a diverse range of novel bacteria, viruses, and other microorganisms in ticks with the potential to cause disease in vertebrate hosts following tick bite. In this study, we describe the isolation and characterization of a novel virus from Bothriocroton hydrosauri ticks collected from a blotched blue-tongue, Tiliqua nigrolutea. In an attempt to isolate rickettsia, the inoculation of Vero cell cultures with tick extracts led to the isolation of a virus, identified as a novel tick Orthomyxovirus by electron microscopy and gene sequencing. Transmission electron microscopic analysis revealed that B. hydrosauri tick virus-1 (BHTV-1) is a spherical orthomyxovirus, 85 nm in size. Multiple developmental stages of the virus were evident in vitro. Analysis of putative BHTV-1 amino acid sequences derived from a genomic analysis of virus-infected host cell extracts revealed the presence of six putative RNA segments encoding genes, sharing the closest sequence similarity to viral sequences belonging to the arthropod-borne Thogotovirus genus within the Orthomyxoviridae. Thogotoviruses are an emerging cause of disease in humans and animals following tick bite. The detection of this new thogotovirus, BHTV-1, in B. hydrosauri, a competent vector for human tick-borne infectious diseases, warrants follow-up investigation to determine its prevalence, host range, and pathogenic potential. Full article

Toxoplasmosis is a parasitic, foodborne infection caused by Toxoplasma gondii. The infection can be transmitted through various routes, including the following: (i) the consumption of vegetables, fruits, or drinking water containing sporulated oocysts; (ii) the consumption of raw or undercooked meat; (iii) transmission from mother to fetus; (iv) through blood transfusion; and (v) transplantation of solid organs, bone marrow, or hematopoietic stem cells. Infection is generally asymptomatic or exhibits a mild clinical presentation in those with adequate immune function; however, the clinical outcomes becomes more severe in both fetal and immunocompromised individuals. In this work, we reviewed the current literature, primarily focusing on epidemiological and neurobiological aspects. Using the PubMed database, we conducted a search by combining the following terms: “Toxoplasma gondii” or “Toxoplasmosis” and “neuropsychiatric” “diseases” or “disorders” or “psychiatric” “diseases” or “disorders” or “neurological” “diseases” or “disorders” or “neurobehavioral disorders” or “behavioral disorders” or “schizophrenia” or “bipolar disorder” or “autism spectrum disorder” or “Parkinson’s disease” or “Alzheimer’s disease”. No language or time restrictions were applied in the literature review, which was concluded in April 2024. Although the literature does not yet provide definitive answers, current data should be considered sufficient to change attitudes toward toxoplasmosis prevention and treatment measures. The focus should be not only with regard to seronegative pregnant women and immunocompromised patients, but also to people particularly prone to developing neuropsychiatric diseases. Full article

Extended-spectrum cephalosporin-resistant Escherichia coli (ESC-EC) poses a significant public health concern, with its presence increasingly detected in healthy humans and various animal species. This study explores the transmission dynamic of ESC-EC within the Danish population as well as the transmission impact of a range of food and animal sources. We developed a compartmental model encompassing farmers, pet owners, and the general population. Additionally, we applied an established source attribution model to estimate the contributions to the transmission of different sources using Danish surveillance data on the distribution of resistance genes in E. coli. Our findings highlight the central role of human-to-human transmission while also showing the significant contributions of food and animal sources to the spread of ESC-EC in sporadic human infections. Imported food, pets, and livestock were estimated to contribute importantly to human infections. The results emphasize the complexity of ESC-EC transmission dynamics and the critical value of employing a One Health approach in modeling disease transmission and in the development of targeted intervention strategies. Full article

Marburg virus (MARV) is one of the deadliest human zoonotic pathogens, historically traced back to Uganda, in East African-cave-dwelling Egyptian fruit bats (Rousettus aegyptiacus), the probable cradle of MARV. Since its first identification in Germany and Serbia in 1967 due to laboratory contamination, MARV has caused 18 outbreaks in humans in Sub-Saharan Africa, with the latest in Tanzania in 2025 and 2023, Rwanda in 2024, and Equatorial Guinea in 2023. Efforts to control MARV through bat extermination in Sub-Saharan Africa have been ineffective, likely due to incomplete extermination and the recolonization of infected juvenile fruit bats. Over the past two decades, extensive molecular epidemiological research has generated over 70 complete MARV genomes, enabling detailed phylogenetic analysis, though bat-derived sequences are still rare. Phylogenetic analysis of Sub-Saharan African Marburgviruses from 1975 shows clustering with sequences from humans and bats, indicating that the virus reservoir species in these regions are not considerably distinct. This review aims to consolidate MARV comprehensive genomic data to provide a clearer picture of the current Marburg virus disease situation in Sub-Saharan Africa and, in turn, highlights the need for active genomic surveillance to identify hotspots and prevent future global outbreaks. Full article

Zoonotic diseases pose a significant global health threat, driven by factors such as globalization, climate change, urbanization, antimicrobial resistance (AMR), and intensified human–animal interactions. The increasing interconnectedness of human, animal, and environmental health underscores the importance of the OH paradigm in addressing zoonotic threats in a globalized world. This review explores the complex epidemiology of zoonotic diseases, the challenges associated with their management, and the necessity for cross-sector collaboration to enhance prevention and control efforts. Key public health strategies, including surveillance systems, infection control measures, and community education programs, play crucial roles in mitigating outbreaks. However, gaps in governance, resource allocation, and interdisciplinary cooperation hinder effective disease management, particularly in low- and middle-income countries (LMICs). To illustrate the effectiveness of the OH approach, this review highlights successful programs, such as the PREDICT project, Rwanda’s National One Health Program, the EcoHealth Alliance, and the Rabies Elimination Program in the Philippines. These initiatives demonstrate how integrating human, animal, and environmental health efforts can enhance early detection, improve outbreak responses, and reduce public health burdens. Strengthening global health governance, enhancing surveillance infrastructure, regulating antimicrobial use, and investing in research and technological innovations are essential steps toward mitigating zoonotic risks. Ultimately, a coordinated, multidisciplinary approach is vital for addressing the dynamic challenges posed by zoonotic diseases and ensuring global health security in an increasingly interconnected world. Full article

Salmonellosis in humans is a public health threat and cattle are important reservoirs for the pathogen. Cattle products such as ground beef have been linked to human salmonellosis outbreaks, and some disease investigations have been traced back to infected animal herds on farms and animal markets as the origin of infection. It is now common to isolate Salmonella from many cattle operations as the pathogen once introduced onto a farm can establish an undesirable endemic condition among herds. It is, therefore, essential to adopt measures to mitigate or prevent the introduction and spread of zoonotic disease agents like Salmonella in animal populations. With this background, the potential sources and risks of Salmonella infection in cattle, the control of already established infection, and other preventative measures are discussed in this article. We conclude that a holistic approach involving all stakeholders in cattle production is needed to safeguard public health, eventually forestalling human salmonellosis from cattle sources. In achieving this, it will be essential to consider the farm as a critical control point in preventing the introduction of Salmonella into the food chain. Full article

The Mpox virus (MPXV), a zoonotic pathogen from the Orthopoxvirus genus, has emerged as a significant global public health concern, especially after the unprecedented outbreak in 2022. This review synthesizes the MPXV’s molecular features, focusing on its genomic structure, replication mechanisms, immune evasion strategies, and implications for diagnostics and therapeutics. The study examines the virus’s genomic organization utilizing recent peer-reviewed literature, highlighting essential genes like OPG027 and D1L, which contribute to host adaptation, increased transmissibility, and immune evasion. Advances in molecular diagnostics, including real-time PCR and genome sequencing, are reviewed, emphasizing their critical role in outbreak monitoring and control. However, challenges persist, such as diagnostic limitations in resource-constrained settings and the lack of targeted vaccines and antivirals. This review discusses new antiviral candidates, confirmed through computational and in vitro techniques, identifying thymidine kinase and VP39 as key therapeutic targets. Emphasizing the need for genomic surveillance to track adaptive evolution, results show that particular mutations, such as in the OPG027 and D1L genes, increase the transmissibility and immune evasion of the MPXV. These molecular revelations highlight the urgent necessity for better diagnostics catered towards addressing present constraints and developing focused treatments that reduce the effect of the virus. This study emphasizes how these results underscore the need for combined public health plans to handle the changing MPXV epidemiology properly. Full article

The One Health approach integrates human, animal, and environmental health to address complex challenges like emerging zoonotic diseases and antimicrobial resistance (AMR). Singapore’s dense urban environment, biodiversity, and role as a global hub make it vulnerable to these health threats, necessitating a robust and coordinated One Health framework. This paper reviews Singapore’s One Health strategy, focusing on governance, surveillance, cross-sector partnerships, and public health infrastructure. A structured literature review, including peer-reviewed articles and grey literature, identified key strengths and gaps. Strengths include interagency coordination through the One Health Coordinating Committee, advanced surveillance systems like CDLENS and SIDPIC, and key institutions such as the National Centre for Infectious Diseases (NCID) and the National Public Health Laboratory (NPHL). However, gaps remain in multi-sector engagement, data-sharing mechanisms, and public awareness of One Health principles. To address these challenges, this paper recommends enhancing multi-sector collaboration, strengthening data-sharing networks, and increasing public education on One Health. Investments in preventive medicine, cross-border capacity-building, and leveraging artificial intelligence for predictive analytics are essential for bolstering Singapore’s health security. By addressing these gaps, Singapore can enhance its preparedness and serve as a global leader in One Health implementation. Full article

The coronavirus disease 2019 (COVID-19) pandemic caused great damage not only in terms of morbidity and mortality, but also intense social, economic, institutional and political disruptions, and costs that upended and challenged assumptions about our preparedness to deal with such global infectious disease threats [...] Full article

Bats and rodents serve as reservoirs for numerous zoonotic pathogens, including species of Trypanosoma and Leishmania. Domestic rats host the flea-transmitted Trypanosoma (Herpetosoma) lewisi, which can be associated with humans, particularly young or immunocompromised individuals. Using Fluorescent Fragment Length Barcoding (FFLB) and phylogenetic analyses based on SSU rRNA sequences, we identified two Herpetosoma species, T. lewisi-like and T. musculi-like species, in bats of different families inhabiting rooftops and peridomestic structures in Brazil (44%, 107 bats examined) and Venezuela (50%, 52 bats examined). These species are typically associated with Rattus spp. (domestic rats) and Mus musculus (house mice), respectively. Furthermore, bats were co-infected with up to five other species, including Trypanosoma dionisii, Trypanosoma cruzi marinkellei, and isolates from the Trypanosoma Neobat clade, all strongly associated with bats, and Trypanosoma cruzi and Trypanosoma rangeli, known to infect various mammals, including humans. Therefore, our findings expand the known host range of Herpetosoma to bats, marking the first report of potential spillover of Herpetosoma trypanosomes from rodents to bats and underscoring the potential for the cross-species transmission of flea-borne trypanosomes. These results highlight the need for a One Health approach to assess infection risks associated with trypanosome spillover from synanthropic rodents and bats to humans. Full article

Highly pathogenic avian influenza (HPAI) surveillance for influenza A virus (IAV) in the United States is conducted using a National Animal Health Laboratory Network (NAHLN) real-time reverse transcriptase–polymerase chain reaction (rRT-PCR). Samples showing the presence of IAV are confirmed and characterized at the national reference laboratory. During the H5N1 HPAI outbreak in 2022, our laboratory reported the detection of IAV in a PA commercial chicken flock using rRT-PCR targeting the matrix gene, which was negative for the H5/H7 subtypes. IAV was not detected by additional sampling of the birds the following day with rRT-PCR. The virus detected was characterized as a human seasonal H3N2 with whole-genome sequencing (WGS). Further investigation revealed that the collector who visited the farm was diagnosed with an IAV infection. This case report emphasizes the importance of farm biosafety and biosecurity, of conducting regular reviews of worker safety protocols, and of advanced molecular techniques like WGS for viral characterization and epidemiology. Full article

Halicephalobus gingivalis (H. gingivalis) is a very rare opportunistic cause of fatal meningoencephalomyelitis in equids but may also cause parasitic infections in exposed humans via zoonotic transmission (from animals to humans). We herein report a 39-year-old veterinarian who was exposed to aspirated gastric contents while inserting a nasogastric tube into a horse with signs of uveitis. This procedure requires application of oral suction to the end of the tube to ensure correct placement. Histopathology of the horse’s enucleated eye later revealed H. gingivalis infection, and the horse developed acute kidney injury, ataxia, and other signs of neurological disease. The horse later progressed to death despite supportive care and administration of the broad-spectrum antiparasitic, ivermectin. Two months later, the veterinarian received prophylactic ivermectin consisting of two 200-mcg/kg doses. The patient reported feeling well and was without any systemic or focal signs or symptoms prior to this prophylactic treatment and continued feeling well when followed up at 4 months post exposure. Blood work was unremarkable, with no eosinophilia (eosinophils 0.1 × 10⁹/L, normal <0.4 × 10⁹/L). Meticulous hand hygiene and alternatives to unprotected oral suction should be considered in veterinary medicine as the potentially increasing risk of occupational exposure to zoonotic helminthiases makes this a public health concern. Full article

Background: Environmental changes impact bat–human interactions, heightening concerns of pathogen spillover and highlighting the need to understand human–bat interactions in the context of ecosystems. The objective of this study was to assess factors associated with human contact with bats in communities living near bat roosts in Northern Tanzania. Methods: A cross-sectional survey was used to investigate the factors associated with human contact with bats. Utilizing a standardized questionnaire administered through face-to-face interviews, relevant data were collected from respondents living in or near regions characterized by high bat density. Descriptive analyses followed by bivariate and multivariate analyses were performed to assess the association between the investigated factors and the outcome variable of interest, contact with bats. Results: Data were collected from 325 respondents. Of the respondents, 57.5% (187/325) reported bat contact, and only 4% believed bats can transmit rabies. The following factors were significantly associated with human–bat contact: being unaware that bats can transmit diseases like rabies (AOR = 8.63, CI = 1.04, 71.43, p = 0.045), feeling safe to handle bats with bare hands (AOR = 3.47, CI = 1.71, 7.05, p < 0.001), not washing hands thoroughly after bat bite or scratch (AOR = 2.43, CI = 1.29, 4.59, p = 0.006), using water from ponds, rivers or wells (AOR = 5.58, CI = 3.17, 9.79, p <0.001), age > 45 years (AOR = 1.77, CI = 1.0, 3.14, p = 0.047) and a low level of education (AOR = 5.86, CI = 2.97, 11.57, p <0.001). Conclusion: The study findings highlight the key factors to be targeted when developing strategies aimed at improving the community’s knowledge of the potential risks of zoonotic infectious diseases associated with bats and reducing the likelihood of human–bat contact and the related public health risks in communities living near bat roosting sites in Tanzania. Full article

Ticks are obligate hematophagous ectoparasites notorious for their role as vectors of pathogens that affect humans and animals, particularly relative to the propagation of emerging infectious diseases (EIDs). Two important factors facilitating the role of ticks in the propagation of EIDs are their potential for the development of resistance to acaricides and the expansion of nonindigenous tick species into new geographic regions. The acquisition of acaricide resistance enables tick populations to be less susceptible to vector control programs. Expansion of the geographic distribution of tick populations increases the likelihood of access to new host species as well as new pathogens. Understanding of the microbiome of ticks continues to evolve, providing critical insights into tick biology. The tick microbiome largely comprises endosymbionts, pathogenic organisms, and commensal bacteria. Endosymbionts are highly preserved and vertically transmitted in ticks from mother to offspring, and their role in the survival of ticks is well recognized. Similarly, the role of ticks as vectors of pathogens is well established. However, commensal bacteria in ticks are acquired from the environment and while ingesting a blood meal. Because many tick species spend most of their lifetime off the hosts, it can be assumed that the richness and diversity of commensal bacteria are highly variable and dependent on the ecosystem in which the tick exists. This mini-review identifies some of the critical data gaps relevant to the role of and influence of commensal bacteria on the vectorial capacity of ticks. As ticks move into new habitats, are locally acquired commensal bacteria playing a role in adaptation to the new habitat? Apart from the conventionally understood mechanisms of acaricide resistance in ticks, are the commensal bacteria influencing the development of acaricide resistance at the population level? Full article

SARS-CoV-2 rapidly mutated, causing different waves of outbreaks worldwide. Bhutan experienced three major outbreaks of COVID-19 before experiencing the outbreak driven by the Omicron variant in January 2022. The data collected by the National Outbreak Investigation and Surveillance Team during the Delta variant-driven outbreak and Omicron outbreak were accessed and analyzed. The data were analyzed using R statistical software. Descriptive analysis was carried out for the entire dataset and the statistical comparison between the two outbreaks was carried out using student’s t-test and Pearson’s chi-square test. During the Delta variant-driven outbreak, a total of 1648 cases were reported, with a daily average of 13 cases. The highest one-day case number reported was 99. On the contrary, within 33 days, a total of 3788 cases were reported with a daily average of 115 cases during the Omicron outbreak. The highest one-day case number reported was 312. The median incubation period was 3 days (range = 0–18 days) and 1 day (range = 0–14 days) during the Delta and Omicron-driven outbreaks, respectively. The number of symptomatic cases was significantly higher during the Delta outbreak (p-value < 0.0001). Of the total cases reported during the Delta outbreak, 1175 (71.3%) had received a single dose of the vaccine, 79 (5%) received two doses, while 394 (24%) were unvaccinated. During the Omicron outbreak, 1957 (52%) cases had received their booster (third dose), 904 (23.8%) received two doses and only 40 (1%) received a single dose of the vaccine. The number of unvaccinated cases was 887 (23.4%), of which 375 (10%) were children below 12 years. Our findings corroborate the enhanced transmissibility of the Omicron variant as reported elsewhere. We report significantly less symptomatic cases during the Omicron outbreak. Further, our data show that the incubation period for the Omicron variant is shorter compared to the Delta variant (p-value < 0.0001). Full article

The aim of this study was to characterize the antimicrobial resistance phenotype and genotype of non-typhoidal Salmonella spp. isolated in Luanda, Angola. Between 2013 and 2015, human clinical samples, food, and environmental samples (n = 290) were collected at different regions of Luanda city and screened for the presence of Salmonella spp. Bacterial isolates were preliminarily identified using the API 20E Kit, and their identification was confirmed using PCR and serotyping. All Salmonella spp. isolates were tested by minimum inhibitory concentration against 19 antimicrobials. The isolates were also screened using PCR for the presence of resistance genes (bla_OXA-1, bla_SHV, bla_TEM, sul1, sul2, sul3, qnrA, qnrB, qnrS, qnrC, qnrD, aac(6′)-Ib, dfrIa [targeting dfrA1, dfrA5, dfrA15, dfrA15b, dfrA16, dfrA16b] and dfrA12, cmlA, and floR) and typed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Salmonella enterica non-typhoidal was detected in 21.3% of the clinical samples (n = 32/150), 11.1% of the food samples (n = 10/90), and 26% of the environmental samples (n = 13/50). Serotyping revealed that the monophasic variant of Salmonella Typhimurium (Salmonella enterica serovar 4,[5],12:i:-) was detected in 38.1% of the samples. Moreover, serovar Salmonella Enteritidis was the second most frequent. Only 7.3% of the isolates were resistant to at least one antimicrobial. Furthermore, isolates from different origins (clinical, environmental, and food) were associated with the same lineages, Salmonella Enteritidis ST11 and S. enterica ser. Typhimurium ST313. The detection of S. enterica serovar 4,[5],12:i:- in different settings reinforces the need for a One Health approach to control this zoonosis in Angola. Full article

A comparative medicine approach, whereby similarities and differences in biology between human and veterinary species are used to enhance understanding for the benefit of both, is highly relevant to the development of viral vaccines. Human and equine influenza share many similarities in pathogenesis and immune responses. The DNA vaccine approach offers potential advantages for responding rapidly and effectively to outbreaks or pandemics in both humans and animals, especially in under-resourced regions. The European and American vaccine regulatory authorities require demonstration of vaccine efficacy in animal models. However, mice, the most widely used model, are not naturally infected with influenza viruses, resulting in different pathobiology. Additionally, mice as a model for DNA vaccine testing appear to overestimate the humoral immune response compared to other mammalian species. In this review, we propose that testing of DNA vaccines against influenza type A viruses (and other shared pathogens) in the horse can provide valuable knowledge for the development of human DNA vaccines. Full article

Some Corynebacterium strains produce toxins that are similar to those produced by Corynebacterium diphtheriae, leading to human infections that are often transmitted through zoonotic diseases. A novel species, which is formerly classified as Corynebacterium ulcerans lineage II, was recently re-evaluated and renamed “Corynebacterium ramonii sp. nov.”. We isolated C. ramonii from a human skin ulcer in Japan in 2023 (KCU0303-001) and identified it as ST344 using a genomic analysis. In addition, C. ramonii KPHES-18084 (ST344) and six strains of C. ulcerans (ST337/ST1011) were isolated from the oral cavities of 7/208 rescued cats (3.4%). The human ulcer strain KCU0303-001 and the rescued cat strain KPHES-18084 were found to be ST344 and closely related clones by core-genome and pan-genome analyses, suggesting that ST344 may be endemic to both clinical and companion animals in Japan. In support of this finding, another clinical isolate of ST344 (TSU-28 strain) was reported in Japan in 2019. Although ST337 is the most common C. ulcerans infection, the second most recent clinical isolate of C. ramonii, ST344, might be increasing; therefore, further genomic surveillance is required to monitor C. ramonii and C. ulcerans infections. Full article

National parks provide visitors access to hiking, camping, and the outdoors. These activities are associated with an increased risk of tick exposure. This brief report is observational, depicting case reports using raw data, and is not intended to analyze or establish risk but rather to examine geographic areas for potential future research and to identify disparities between canine and human disease reports within the same location. Locally vs. travel-acquired data are not provided by most public health departments in the U.S. Therefore, multimodal data analyses are needed for an improved understanding of disease risk. With data limitations in mind, observations from human and canine comparisons, in addition to tick presence, in this report include (1) tick-borne diseases are reported at most national park areas in the U.S., with the highest case reports in park areas located in Maine and Minnesota; (2) the average total tick-borne diseases combined (i.e., Lyme disease, ehrlichiosis, and anaplasmosis) for park areas allowing dogs is 15.34%. In comparison, the average for national parks without dogs is 8.7%, indicating the need for further study to assess human activity with pets, considering geography and ecology as potential explanatory factors; (3) canine data do not align with human data in many national park geographic areas; and (4) Ixodes scapularis presence overlaps with human and canine disease. Using multimodal data can assist with assessing risk when travel vs. local acquisition is unknown. Full article