Zoonotic Diseases

Colpodella species are free-living predatory protists that prey on algae, ciliates and bodonids using myzocytosis. Colpodella species have been reported in human and animal infections. Polymerase chain reaction (PCR) using primers targeting 18S rRNA genes of Cryptosporidium and piroplasms have identified Colpodella species in arthropods, host blood and feces, demonstrating the phylogenetic closeness of Colpodella species to the apicomplexa. However, in human, animal and arthropod hosts, the life cycle stages of Colpodella are unknown. In this literature review, we provide an overview of the widespread occurrence of Colpodella species in ticks, and pathogenicity in humans and animals. We discuss methods for culture and microscopy that can aid diagnosis. Phylogenetic tree analysis of Colpodella species identified using 18S rRNA demonstrates that the Colpodella species identified in different geographic regions represent different species and strains that may impact virulence and zoonotic transmission. There is a pressing need to culture Colpodella species, and to stain cells for morphological identification. This will aid molecular investigations aimed at identifying molecular markers of Colpodella spp. facilitating transmission, survival and pathogenesis in hosts, and will determine which species and strains to prioritize for the risk of zoonotic infections to humans and for infections in animals. Full article

Zoonotic diseases present a growing public health challenge, particularly in sub-Saharan Africa (SSA) due to close interactions between humans and animals and poor diagnostic capacity. This pilot study investigated human exposure to zoonotic pathogens in Zambia among 47 suspected COVID-19 patients from whom nasopharyngeal samples were collected between November 2020 and February 2021 at two major COVID-19 referral centers in Lusaka. Using metagenomic next-generation sequencing (mNGS), the study identified a diverse range of pathogens, including bacterial, fungal, viral, and parasitic species. The prevalence of zoonotic pathogens was 57.4%. Noteworthy zoonoses included Bacillus anthracis, Sporothrix schenckii, Listeria monocytogenes, Yersinia pestis, Streptococcus suis, Vibrio parahaemolyticus, Brucella melitensis, Rickettsia prowazekii, Shewanella algae, Rickettsia japonica, Coxiella burnetii, Leptospira borgpetersenii, Erysipelothrix rhusiopathiae, Brucella abortus, Bartonella quintana, Banna virus, Vibrio alginolyticus, Bartonella clarridgeiae, Rickettsia canadensis, Leishmania braziliensis, Trypanosoma brucei, Pasteurella multocida, and Arcobacter butzleri. Despite moderate diversity in the microbial community, no significant demographic or health-related factors, including age, gender, or comorbidities such as HIV, were found to be statistically associated with zoonotic pathogen infection. The findings provide valuable data on the presence of zoonotic pathogens in humans in Zambia and highlight the need for more comprehensive research into zoonotic diseases in both clinical and non-clinical settings. Full article

The human coronavirus 229E (HCoV-229E) is a member of the human coronavirus family that includes SARS-CoV-2, the causative agent of COVID-19. Developing antiviral strategies and compounds is crucial to treat and prevent HCoV-229E infections and the associated diseases. Ribozymes derived from ribonuclease P (RNase P) catalytic RNA represent a novel class of promising gene-targeting agents by cleaving their target mRNA and knocking down the expression of the target mRNA. However, it has not been reported whether RNase P ribozymes block the infection and replication of HCoV-229E. We report here the engineering of an anti-HCoV-229E RNase P ribozyme to target an overlapping region of viral genomic RNA and the mRNA encoding the nucleocapsid (N) protein, which is vital for viral replication and growth. The engineered ribozyme actively hydrolyzed the viral RNA target in vitro. HCoV-229E-infected cells expressing the engineered, catalytically active ribozyme exhibited a reduction of about 85% in viral RNA levels and N protein expression, and a reduction of about 750-fold in infectious particle production, compared to cells expressing no ribozymes or a control, catalytically inactive ribozyme. Our study provides the first direct evidence of the therapeutic potential of RNase P ribozymes against human coronaviruses such as HCoV-229E. Full article

Though a variety of methods are used to conduct West Nile virus (WNV) surveillance, accurate prediction and prevention of outbreaks remain a global challenge. Previous studies have established that the concentration of antibodies to mosquito saliva is directly related to the intensity of exposure to mosquito bites and can be a good proxy to determine risk of infection in human populations. To assess exposure characteristics and transmission dynamics among avian communities, we tested the levels of IgY antibodies against whole salivary glands of Aedes albopictus and Culex quinquefasciatus, as well as WNV antigen, in 300 Northern cardinals sampled from April 2019 to October 2019 in St. Tammany Parish, Louisiana. Though there were no significant differences in antibody responses among sex or age groups, exposure to Ae. albopictus bites was more positively associated with exposure to WNV compared with Cx. quinquefasciatus exposure (ρ = 0.2525, p < 0.001; ρ = 0.1752, p = 0.02437). This association was more pronounced among female birds (ρ = 0.3004, p = 0.0075), while no significant relationship existed between exposure to either mosquito vector and WNV among male birds in the study. In general, two seasonal trends in exposure were found, noting that exposure to Ae. albopictus becomes less intense throughout the season (ρ = −0.1529, p = 0.04984), while recaptured birds in the study were found to have increased exposure to Cx. quinquefasciatus by the end of the season (ρ = 0.277, p = 0.0468). Additionally, we report the identification of several immunogenic salivary proteins, including D7 family proteins, from both mosquito vectors among the birds. Our results suggest that Ae. albopictus may have a role in early-season transmission of WNV, particularly among brooding females and hatchling cardinals. However, bloodmeal analysis was not included in this work and further studies are needed to verify this assumption. Yet, broad circulation of WNV in nesting avian communities could enhance risk of infection among Cx. quinquefasciatus mosquitoes in the late season, with the potential to contribute to human disease incidence and epizootic spillover in the environment. Full article

Rodent-borne diseases threaten global public health, impacting the urban poor. Despite widespread application of rodenticide in rodent/rodent-borne disease control programs, empirical evidence demonstrating their effectiveness is lacking. This review proposed guidelines for designing and implementing empirical studies on rodenticides as public health measures. The recommendations include: (i) the importance of the type of quasi-experimental design adopted, and how it creates robust evidence; (ii) how urban slums present both challenges for control and ideal settings for studies; (iii) partnering with pest control authorities and community engagement for long-term viability; (iv) leveraging zoonotic systems with direct/environmental transmission, reliable diagnosis, and high prevalence for effectivity assessment; (v) pairing human cohort studies to observe epidemiological links; (vi) systematic data collection and management protocols; (vii) short- and long-term goals for critical evaluation and course-correction; (viii) focus on mechanistic approach; (ix) the need for standardized reporting of the findings. Full article

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