Zoonotic Dis., Volume 5, Issue 2 (June 2025) – 7 articles

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