Toxocariasis: a silent threat with a progressive public health impact

Larvicidal activity of coumarin derivatives on Toxocara canis larvae, cytotoxicity analysis, and in silico bioavailability studies

Human toxocariasis is a neglected anthropozoonosis with global distribution. Treatment is based on the administration of anthelmintics; however, their effectiveness at the tissue level is low to moderate, necessitating the discovery of new drug candidates. Several groups of synthetic compounds, including coumarin derivatives, have demonstrated bioactivity against fungi, bacteria, and even parasites, such as Dactylogyrus intermedius, Leishmania major, and Plasmodium falciparum. The aim of this study was to evaluate the effect of ten coumarin-derived compounds against Toxocara canis larvae using in vitro, cytotoxicity, and in silico tests for selecting new drug candidates for preclinical tests aimed at evaluating the treatment of visceral toxocariasis. The compounds were tested in vitro in duplicate at a concentration of 1 mg/mL, and compounds with larvicidal activity were serially diluted to obtain concentrations of 0.5 mg/mL; 0.25 mg/mL; 0.125 mg/mL; and 0.05 mg/mL. The tests were performed in a microculture plate containing 100 T. canis larvae in RPMI-1640 medium. One compound (COU 9) was selected for cytotoxicity analysis using J774.A1 murine macrophages and it was found to be non-cytotoxic at any concentration tested. The in silico analysis was performed using computational models; the compound presented adequate results of oral bioavailability. To confirm the non-viability of the larvae, the contents of the microplate wells of COU 9 were inoculated intraperitoneally (IP) into female Swiss mice at 7-8 weeks of age. This confirmed the larvicidal activity of this compound. These results show that COU 9 exhibited larvicidal activity against T. canis larvae, which, after exposure to the compound, were non-viable, and that COU 9 inhibited infection in a murine model. In addition, COU 9 did not exhibit cytotoxicity and presented adequate bioavailability in silico, similar to albendazole, an anthelmintic, which is the first choice for treatment of human toxocariasis, supporting the potential for future investigations and preclinical tests on COU 9.

Ocular Brugia pahangi Filariasis Complicated by Severe Macular Damage in Thailand: Case Report and Literature Review

Extralymphatic filariasis caused by filaria of zoonotic origins has been frequently reported in Thailand over recent years. Here, we report the first case of ocular filariasis in a 7.5-year-old Thai boy who initially presented with progressive conjunctival redness and blurred vision in his right eye. A small, slender, coiled worm was found and surgically removed from the right anterior chamber. Histopathological examination illustrated predominant eosinophilic inflammation surrounding the parasite, which showed smooth and thin cuticle, prominent lateral chords, flat and broad muscle cells, one intestine, and two reproductive tubes with unsegmented ova, typically characteristic of a female adult Brugia filarial nematode. The parasite was also molecularly identified as B. pahangi, based on mitochondrial cytochrome c oxidase subunit I sequence analysis. The patient was then empirically prescribed albendazole, systemic prednisolone, and topical methylprednisolone. Unfortunately, his vision did not recover after 2 months due to severe maculopathy, most likely resulting from parasitic infestation and subsequent vitreous inflammation. To the best of our knowledge, this is the first case of ocular infestation by B. pahangi with visual complications that occurred outside a filariasis-endemic area of Thailand. Furthermore, this report provides clinical data on preceding cases of B. pahangi filariasis formally reported in southeast Asian countries, including Thailand and Malaysia, which facilitate a better understanding of the epidemiology of this sporadic zoonotic infection for effective disease elimination.

Synergistic effects of using sodium hypochlorite (bleach) and desiccation in surface inactivation for Toxocara spp

Toxocara cati and T. canis are parasitic nematodes found in the intestines of cats and dogs respectively, with a cosmopolitan distribution, and the potential for anthropozoonotic transmission, resulting in human toxocariasis. Spread of Toxocara spp. is primarily through the ingestion of embryonated eggs contaminating surfaces or uncooked food, or through the ingestion of a paratenic host containing a third-stage larva. The Toxocara spp. eggshell is composed of a lipid layer providing a permeability barrier, a chitinous layer providing structural strength, and thin vitelline and uterine layers, which combined create a biologically resistant structure, making the Toxocara spp. egg very hardy, and capable of surviving for years in the natural environment. The use of sodium hypochlorite, household bleach, as a disinfectant for Toxocara spp. eggs has been reported, with results varying from ineffective to limited effectiveness depending on parameters including contact time, concentration, and temperature. Desiccation or humidity levels have also been reported to have an impact on larval development and/or survival of Toxocara spp. eggs. However, to date, after a thorough search of the literature, no relevant publications have been found that evaluated the use of sodium hypochlorite and desiccation in combination. These experiments aim to assess the effects of using a combination of desiccation and 10% bleach solution (0.6% sodium hypochlorite) on fertilized or embryonated eggs of T. cati, T. canis, and T. vitulorum. Results of these experiments highlight the synergistic effects of desiccation and bleach, and demonstrate a relatively simple method for surface inactivation, resulting in a decrease in viability or destruction of T. cati, T. canis and T. vitulorum eggs. Implications for these findings may apply to larger scale elimination of ascarid eggs from both research, veterinary, and farming facilities to mitigate transmission.

The impact of Toxocara-seropositivity on attention and motor skills in children with attention-deficit hyperactivity disorder

BACKGROUND

The study aims to compare neurological soft signs and executive functions between Toxocara-seropositive and seronegative groups in children with attention-deficit/hyperactivity disorder.

METHODS

The study included 60 boys with ADHD, aged 7-12. After blood samples were taken, the Stroop Color Word Test and Judgment of Line Orientation test (JLOT) were implemented to measure executive functions. Neurological soft signs were evaluated with Physical and Neurological Examination for Subtle Signs (PANESS).

RESULTS

Serological tests were positive for Toxocara antibodies in 20 cases. There was no significant difference between Toxocara seropositive and seronegative regarding age, socioeconomic status, developmental stages, and ADHD severity. However, Toxocara-seropositive children had higher Stroop time and Stroop interference scores and lower JLOT scores than Toxocara-seronegative children. Furthermore, Toxocara-seropositive children exhibited more neurological soft signs, such as gait and station abnormalities, dysrhythmia, and a longer total time in timed movements compared to Toxocara-seronegative children.

CONCLUSION

Our study indicates a link between Toxocara-seropositivity and impaired neurological soft signs and executive functions in ADHD. Further research is needed to understand ADHD mechanisms, develop practical treatments considering immunological factors, and thoroughly evaluate how Toxocara seropositivity affects executive functions and motor skills in children with ADHD.

Quantifying the neglected: Initial estimation of the global burden and economic impact of human toxocariasis

Toxocariasis is a parasitic zoonotic infection caused by Toxocara spp., ascarid nematodes of companion animals (dogs and cats) affecting people in both high-income and low/middle-income countries. Toxocariasis can manifest as several distinct syndromes. The most frequent, often termed common toxocariasis, is a self-limiting and mild febrile illness. Ocular and visceral larva migrans are severe disease manifestations affecting the eye and other internal organs, respectively, but their reported occurrence is rare. The vast majority of symptomatic cases are thought due to common toxocariasis, which has also been associated with cognitive impairment in children. Few studies to date have sought to quantity the health burden of toxocariasis in humans. In this study we provide a preliminary estimation using the Disability-Adjusted Life Year (DALY) approach. We estimate a total of 23,084 DALYs are lost annually in 28 selected countries due to common toxocariasis. Extrapolating based on a global average seroprevalence rate of 19%, we estimate 91,714 DALYs per year are lost across all countries due to toxocariasis, of which 40,912 are attributable to less severe forms, i.e. common toxocariasis, and 50,731 to cognitive impairment in children. Clinically diagnosed and reported ocular and visceral larva migrans represent a small proportion of estimated total health burden. We also found a positive correlation at national level between prevalence in cats or dogs and seroprevalence in humans, but no correlation between estimated soil contamination and seroprevalence in humans. Finally, we estimate the potential economic impact of toxocariasis in selected countries at 2.5 billion USD per annum, from costs of medical treatment and lost income. These preliminary estimates should serve as a call to action for further research and evidence-based measures to tackle toxocariasis.

Proteomic change in the upper lobe of the left lung of Beagle dogs at the lung migration stage of Toxocara canis infection

BACKGROUND

Toxocara canis is considered one of the most neglected parasitic zoonoses and threatens the health of millions of people worldwide with a predilection for pediatric and adolescent populations in impoverished communities. Exploring the invasion and developmental mechanisms associated with T. canis infection in its definitive canine hosts will help to better control zoonotic toxocariasis.

METHODS

Proteomic changes in samples from the upper lobe of the left lung of Beagle puppies were systematically analyzed by quantitative proteomic technology of data-independent acquisition (DIA) at 96 h post-infection (hpi) with T. canis. Proteins with P-values < 0.05 and fold change > 1.5 or < 0.67 were considered proteins with differential abundance (PDAs).

RESULTS

A total of 28 downregulated PDAs and 407 upregulated PDAs were identified at 96 hpi, including RhoC, TM4SFs and LPCAT1, which could be associated with the maintenance and repair of lung homeostasis. GO annotation and KEGG pathway enrichment analyses of all identified proteins and PDAs revealed that many lung proteins have correlation to signal transduction, lipid metabolism and immune system.

CONCLUSIONS

The present study revealed lung proteomic alterations in Beagle dogs at the lung migration stage of T. canis infection and identified many PDAs of Beagle dog lung, which may play important roles in the pathogenesis of toxocariasis, warranting further experimental validation.

Understanding the research and practical needs required to control toxocariasis in Iran

Human toxocariasis (HT) is a widespread zoonotic infection globally, notably prevalent in tropical areas. Enhancing our understanding of toxocariasis can lead to increased attention towards the socioeconomic impact and control of this neglected zoonosis. We conducted a comprehensive review of all available articles and official documents on toxocariasis in Iran to identify research gaps and critical needs for its control. This review highlights that despite numerous studies exploring various aspects of toxocariasis in definitive and paratenic hosts, as well as humans and environmental contamination, significant data deficiencies and gaps persist across different regions in the country. These gaps involve investigating the worm burden and reinfection rates in definitive hosts, developing more sensitive methods to detect and differentiate of Toxocara species, and understanding the behavior of definitive host animals. Additionally, identifying potential paratenic hosts for HT and exploring the organ-specific affinity and survival duration of Toxocara larvae within these hosts are essential areas for exploration. It's also imperative to comprehend the sylvatic and domestic cycles of the parasite in paratenic hosts. Furthermore, assessing egg density in the environment, exploring potential new sources such as water, and identifying regions with optimal climatic conditions for the survival and development of Toxocara eggs are crucial for the formulation of effective prevention and control strategies. Identifying at-risk groups, developing early diagnosis techniques, employing imaging methods, and identifying long-term complications in humans are also crucial. Community health organizations should prioritize health education for the public and professionals. Furthermore, accurately estimating definitive host populations, monitoring and preventing their movements in public places, implementing regular deworming practices for pets and stray hosts, and recognizing the infection's significance as a health priority are critical. This comprehensive understanding advocates for a holistic "one health" approach to control of HT.

Causes of infectious pediatric uveitis: A review

Infectious pediatric uveitis is a rare disease that can cause severe ocular damage if not detected rapidly and treated properly. Additionally, early identification of an infection can protect the child from life-threatening systemic infection. Infectious uveitis can be congenital or acquired and may manifest as a primary ocular infection or as a reactivation. Nevertheless, publications on infectious paediatric uveitis are usually limited to a small number of patients or a case report. So far, most studies on uveitis in children have focused primarily on noninfectious uveitis, and a systematic study on infectious uveitis is lacking. In this review, we summarize the literature on infectious uveitis in pediatric populations and report on the epidemiology, pathophysiology, clinical signs, diagnostic tests, and treatment. We will describe the different possible pathogens causing uveitis in childhood by microbiological group (i.e. parasites, viruses, bacteria, and fungi). We aim to contribute to early diagnosis and management of infectious pediatric uveitis, which in turn might improve not only visual outcome, but also the general health outcome.

Coinfection of Ocular Toxoplasmosis and Ocular Toxocariasis in the Same Patient

PURPOSE

To report a rare case of a toxoplasma chorioretinitis in one eye and peripheral ocular toxocariasis granuloma in the fellow eye of the same patient.

MATERIALS AND METHODS

Retrospective case report.

RESULTS

A 44-year-old male presented with gradual loss of vision over the past weeks. The patient was diagnosed with ocular toxoplasma chorioretinitis recurrence in his right eye and an inactive peripheral granuloma of ocular toxocariasis was found in the left eye. The patient was a farmer who had been involved in animal husbandry throughout his life. The patient was treated with antibiotics for toxoplasma chorioretinitis and kept under follow-up for ocular toxocariasis.

CONCLUSION

Coinfections of zoonoses are related to socioeconomic environment and individual characteristics of the host. Ocular toxoplasmosis and ocular toxocariasis may present with different scenarios. To our knowledge, this is the first case of a coinfection of ocular toxoplasmosis and ocular toxocariasis in the same patient. A thorough ophthalmological examination and detailed anamnesis are important for diagnosis.

C-type lectin 4 of Toxocara canis activates NF-ĸB and MAPK pathways by modulating NOD1/2 and RIP2 in murine macrophages in vitro

Toxocara canis is a parasitic zoonose that is distributed worldwide and is one of the two pathogens causing toxocariasis. After infection, it causes serious public health and safety problems, which pose significant veterinary and medical challenges. To better understand the regulatory effects of T. canis infection on the host immune cells, murine macrophages (RAW264.7) were incubated with recombinant T. canis C-type lectin 4 (rTc-CTL-4) protein in vitro. The quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to analyze the nucleotide-binding oligomerization domain-containing protein 1/2 (NOD1/2), receptor-interacting protein 2 (RIP2), nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), and mitogen-activated protein kinase (MAPK) on mRNA level and protein expression level in macrophages. Our results indicated that 10 μg/mL rTc-CTL-4 protein could modulate the expression of NOD1, NOD2, and RIP2 at both the transcriptional and translational levels. The protein translation levels of NF-κB, P-p65, p38, and P-p38 in macrophages were also modulated by rTc-CTL-4 protein. Macrophages were co-incubated with rTc-CTL-4 protein after siRNA silencing of NOD1, NOD2, and RIP2. The expression levels of NF-κB, P-p65, p38, and P-p38 were significantly changed compared with the negative control groups (Neg. Ctrl.). Taken together, rTc-CTL-4 protein seemed to act on NOD1/2-RIP2-NF-κB and MAPK signaling pathways in macrophages and might activate MAPK and NF-κB signaling pathways by regulating NOD1, NOD2, and RIP2. The insights from the above studies could contribute to our understanding of immune recognition and regulatory mechanisms of T. canis infection in the host animals.

Anthelmintic efficacy of nitazoxanide in dogs naturally infected with Toxocara canis

Toxocara canis (T. canis) is a gastrointestinal nematode in dogs, and its larvae also infect humans, causing severe larval migratory disease. Anthelmintic drugs have become the primary means to combat T. canis. In this study, the efficacy of nitazoxanide (NTZ) was tested against all the internal stages of T. canis, including L3 larval stage in vitro experiments and gastrointestinal worm in vivo experiments. In the in vitro experiment, after treatment with NTZ at 7.81 and 62.5 μg/mL for 12 h, the larval mortality efficacy reached 90.0 and 100.0%, respectively. In the in vivo experiments, 100 mg/kg NTZ possessed good anthelmintic efficacy against T. canis, with an egg per gram (EPG) reduction of 99.19%, and 90.00% of dogs cleared with residual worms. These results were comparable to those of the positive control drug. The highest anthelmintic efficacy was observed in the group treated with 150 mg/kg NTZ. Based on faecal egg counts, the number of T. canis eggs decreased by 100.00%, and the percentage of dogs cleared with residual worms achieved 90.00% after 7 days of treatment in the 150-mg/kg NTZ treatment group. In general, NTZ showed great potential to be applied as an anthelmintic against T. canis.

Presumptive pulmonary toxocariasis in a patient affected by acute myeloid leukemia and Hodgkin lymphoma: case report and review of the literature in immunocompromised hosts

Toxocariasis is a zoonosis transmitted by the nematode Toxocara spp. Immunocompromised hosts are more susceptible than general population to bacterial, viral, fungal and parasitic infections. In this population toxocariasis may present as exacerbation or reactivation and could have severe or atypical manifestations being a diagnostic challenge for healthcare providers. We report a case of a presumptive pulmonary toxocariasis during chemotherapy in a patient affected by acute myeloid leukaemia (AML) and Hodgkin lymphoma and we summarize current evidence of pulmonary involvement in immunocompromised population with Toxocara spp infection in a narrative review. The aim of this work is also to revise the current literature on pulmonary involvement during Toxocara spp infection in immunocompromised hosts to improve knowledge on clinical presentation, treatment and outcome. A 66 years old man who had undergone to a cytarabine and idarubicin chemotherapy induction scheme for AML, complained of febrile neutropenia and dry cought. At the chest computed tomography (CT) there were multiple nodular pulmonary lesions with subpleural consolidations. The lung biopsy revealed inflammatory infiltration with diffuse small granulomas with minor eosinophil component. The laboratory analysis showed high immunoglobulin E (IgE) count with normal peripherical eosinophils, among the extended parasitological analysis, Toxocara immunoblot assay resulted positive. In the most accepted hypothesis of a polmunary toxocariasis infection, the patient was treated with a combination of albendazole plus corticosteroids for four weeks, with a positive outcome. Infection complications during chemotherapy are not uncommon, however, this is the first reported case of pulmonary toxocariasis during cytarabine and idarubicin treatment in AML. The revised literature shows male gender and younger age as possible risk factors, nevertheless the majority of cases of seropositivity for Toxocara was reported in solid organ malignancies. In this case, the suspect was mainly based on laboratory total elevated IgE, confirmed by serological, anatomo-pathological and radiological findings. Hypereosinophilia is often not present in chronic infection. In conclusion, pulmonary toxocariasis should be ruled out in patients with pulmonary involvement and high IgE titre, with or without peripheral eosinophilia, especially in those with known immunocompromised status.

Serosurvey of Toxoplasma gondii and Toxocara spp. co-infection in pregnant women in low-income areas of Brazil

Introduction

Despite human toxoplasmosis and toxocariasis having been listed among the top six most neglected parasitic zoonoses worldwide, presenting similar associated risk factors and transmission routes, few studies have been conducted in pregnant women and the consequences of concurrent infection remain to be fully established. Accordingly, the present study has serologically assessed the co-infection and associated risk factors for Toxoplasma gondii and Toxocara spp. in pregnant women, assisted by the public Unified National Health System (SUS) in southeastern Brazil.

Materials and Methods

Blood samples were collected and tested for IgG antibodies against Toxoplasma gondii by chemiluminescence immunoassay and against Toxocara spp. by enzyme-linked immunosorbent assay (ELISA). An epidemiological questionnaire was applied to gather socioeconomic information to assess the risk factors associated with seropositivity to toxocariasis/toxoplasmosis by univariate analysis followed by logistic regression.

Results

Overall, seropositivity was 69/280 (24.6, 95% CI: 19.96-30.01) for T. gondii and 56/280 (20.0, 95% CI: 15.73-25.08) for Toxocara spp. Co-infection was observed in 25/280 (8.9, 95% CI: 6.12-12.85) pregnant women, with increased odds (OR: 3.3, CI 95%: 1.77-6.14, p = 0.0002). Logistic regression revealed that a higher educational level (high school or college) significantly reduced the likelihood of co-infection seropositivity, owning cats increased the odds of toxocariasis, and older pregnant women presented significantly higher T. gondii seropositivity.

Conclusion

Co-infection herein highlights the importance of educational programs in the prevention of toxocariasis and toxoplasmosis in pregnant women and other high-risk populations.

Ocular Toxocariasis in Adult Caucasian Patients: Clinical Presentations and Treatment Outcomes

PURPOSE

To report the clinical features and treatment outcomes in adult Caucasians with ocular toxocariasis (OT) and investigate their prognosis depending on their serological status.

METHODS

Retrospective observational cohort study (2016-2021) including consecutive adults with uveitis and positive western blot (WB) in the aqueous humor or vitreous. The presence of serum antibodies was not necessary for inclusion, allowing to compare the outcomes depending on the serological status.

RESULTS

Seventeen eyes of 15 patients were included. Mean age at diagnosis was 51.9 years. Vitreous inflammation was the most frequent sign (100%). Vitreoretinal tractions (41.2%) and chorioretinal granulomas (58.8%) were less prevalent. Atypical features were: spontaneous intravitreal hemorrhage (23.5%), exudative retinal detachment (11.8%), isolated macular edema (17.6%), papillitis (29.4%) and vasculitis (47.1%). Twenty percent of patients had a positive serum serology. Baseline clinical features did not differ statistically depending on the serological status; however, the degree of inflammation was numerically higher in patients with negative serology. Overall, macular thickness, anterior and posterior segment inflammation improved significantly after treatment with oral albendazole, systemic ± local corticosteroids. Vitrectomy (47.1%) was performed in case of persistent vitritis (62.5%), retinal detachment (12.5%) and intravitreous hemorrhage (25%).

CONCLUSION

OT has no pathognomonic sign and atypical presentations were not infrequent in this adult Caucasian cohort. Serum antibodies were rarely positive, stressing on the importance of ocular sample analysis, especially in case of atypical features. Serum antibodies may prove useful in forecasting the rapidity of inflammation clearance. Antiparasitic and anti-inflammatory treatment was safe and efficient in most cases.

The immunomodulatory effects of the C-type lectin protein of Toxocara canis on experimental autoimmune encephalomyelitis

Toxocara canis is a global zoonosis infection that can cause chronic and long-term toxocariasis in their paratenic host. The excretory-secretory (ES) products of T. canis larvae are considered to be responsible for the Th2 polarization and regulatory immune responses in toxocariasis. The C-type lectin family is one of the most prominent components of ES products of T. canis infective larvae. This study aimed to investigate the ameliorative effect of a T. canis C-type lectin recombinant protein (rCTL), on experimental autoimmune encephalomyelitis (EAE) which is a T-cell-mediated autoimmune disease of the central nervous system. C57BL/6 mice were subcutaneously treated with 30 μg rCTL, three times at an interval of 1 week. EAE was induced by myelin oligodendrocyte glycoprotein 35-55 peptide (MOG35-55 peptide) immunization, and weight and clinical scores were evaluated. Real time polymerase chain reaction was performed to evaluate the expression levels of T-bet, Gata3, and Foxp3 in splenocytes. In addition, the levels of interleukin 4, interferon gamma, and tumour growth factor-β (TGF-β) were quantified by enzyme-linked immunosorbent assay in splenocyte culture supernatants. The results indicated that the rCTL decreased clinical disability scores and delayed the onset of EAE. Furthermore, the data showed that rCTL treatment modulated the immune response, which was associated with upregulation of the mRNA expression of the Foxp3 gene and higher production of TGF-β in rCTL-treated mice. This study demonstrated that rCTL might be a potential agent to ameliorate EAE symptoms by stimulating anti-inflammatory responses.

Prevalence of intestinal parasites in street dogs (Canis lupus familiaris) with highlights on zoonosis in Lalitpur, Nepal

BACKGROUND

The presence of intestinal parasites influences the growth and well-being of canids. Additionally, infected dogs and their faeces with considerably higher eggs/oocysts released per gram (epg/opg) of zoonotic parasites contribute to parasitic spillover to humans, domestic animals and sympatric wildlife.

OBJECTIVES

The current study aimed to reveal the prevalence of intestinal parasites (protozoa and helminths) and to list the zoonotically significant parasites in free-roaming street dogs in Lalitpur Metropolitan City, Nepal.

METHODS

Fresh faecal samples (n = 332) were collected from feral dogs of varying ages and sexes and transported to the research laboratory. The copro microscopic examination was carried out via direct wet mount, formalin ethyl acetate sedimentation, saturated salt flotation, acid-fast staining and sporulation techniques.

RESULTS

Coproscopy revealed an overall 95.7% (318/332) prevalence rate with 23 diverse species of intestinal parasites (10 protozoa and 13 helminths). Among them, 5 protozoa and 11 helminths possessed zoonotic potential, and their overall prevalence was 92.5%. Helminth's overall prevalence was double that of the protozoa (87.7% vs. 43%). Polyparasitism was dominant over mono parasitism (79.5% vs. 16.3%), and co-infection of up to seven species of parasites at a time was recorded.

CONCLUSIONS

Urban street dogs harboured a higher prevalence of intestinal parasites that varied with age and sex. Since most of the reported parasites are zoonotic, dog density and parasitic richness indicate a greater spillover risk to humans and domestic animals. Furthermore, this study also provides appropriate 'baseline' data for assessing effective control measures against parasitic infestations among street dogs and controlling their transmission to humans.

A Study on the Monitoring of Toxocara spp. in Various Children's Play Facilities in the Republic of Korea (2016-2021)

Toxocara spp. is a zoonotic soil-transmitted parasite that infects canids and felids, which causes toxocariasis in humans, migrating to organ systems, including the lungs, the ocular system, and the central nervous system. Since Toxocara spp. is usually transmitted through soil, children tend to be more susceptible to infection. In order to monitor contamination with Toxocara spp. in children's play facilities in the Republic of Korea, we investigated 11,429 samples of soil from daycare centers, kindergartens, elementary schools, and parks across the country from January 2016 to December 2021. Since the Environmental Health Act in the Republic of Korea was enacted in March 2008, there have been sporadic reports of contamination by Toxocara spp. in children's activity zones. In this study, soil from children's play facilities in regions across the Republic of Korea was monitored according to the Korean standardized procedure to use it as basic data for preventive management and public health promotion. The national average positive rate was 0.16% (18/11,429), and Seoul showed a higher rate of 0.63% (2/318) than any other regions while Incheon, Daegu, Ulsan, Kangwon-do, Jeollabuk-do, and Jeollanam-do were negative (p < 0.05). The positive rates were as follows: 0.37% (4/1089) in daycare centers, 0.13% (3/2365) in kindergartens, 0.2% (7/4193) in elementary schools, 0.09% (1/1143) in apartments, and 0.14% (3/2198) in parks. In addition, it was confirmed that 0.2% (1/498) of elementary schools and 1.17% (2/171) of parks were re-contaminated among play facilities managed with the establishment of a regular inspection cycle. Consequently, there is an essential need for continuous monitoring of Toxocara spp. contamination and regular education for preschool and school children in order to prevent soil-borne parasite infections.

Who Let the Dogs Out? Unmasking the Neglected: A Semi-Systematic Review on the Enduring Impact of Toxocariasis, a Prevalent Zoonotic Infection

Toxocariasis remains an important neglected parasitic infection representing one of the most common zoonotic infections caused by the parasite Toxocara canis or, less frequently, by Toxocara cati. The epidemiology of the disease is complex due to its transmission route by accidental ingestion of embryonated Toxocara eggs or larvae from tissues from domestic or wild paratenic hosts. Even though the World Health Organization and Centers for Disease Control classified toxocariasis amongst the top six parasitic infections of priority to public health, global epidemiological data regarding the relationship between seropositivity and toxocariasis is limited. Although the vast majority of the infected individuals remain asymptomatic or experience a mild disease, the infection is associated with important health and socioeconomic consequences, particularly in underprivileged, tropical, and subtropical areas. Toxocariasis is a disease with multiple clinical presentations, which are classified into five distinct forms: the classical visceral larva migrans, ocular toxocariasis, common toxocariasis, covert toxocariasis, and cerebral toxocariasis or neurotoxocariasis. Anthelmintic agents, for example, albendazole or mebendazole, are the recommended treatment, whereas a combination with topical or systemic corticosteroids for specific forms is suggested. Prevention strategies include educational programs, behavioral and hygienic changes, enhancement of the role of veterinarians, and anthelmintic regimens to control active infections.

Case report: Probable toxocariasis in a Swiss adult patient with hypereosinophilic syndrome and multiorgan involvement

Hypereosinophilic syndromes are a heterogeneous group of rare diseases characterized by eosinophil-related organ damage and peripheral blood hypereosinophilia. Hypereosinophilic syndromes may occur secondary to a variety of clinical entities, for example, drug hypersensitivity reactions, parasitic infections, autoimmune disorders, and malignancies. Toxocariasis is a parasitic infection caused by the larval stage of the Toxocara species. It is usually a childhood disease and invades organs such as the liver but can affect any organ. Hypereosinophilic syndrome and multiorgan involvement are very rare manifestations of Toxocara infection, especially in adults. However, the disease may be underdiagnosed because of different factors, including a lack of laboratory infrastructure in some countries, a lack of uniform case definitions, and limited surveillance infrastructure, with its estimation constituting a challenge. We, therefore, present a probable case of hypereosinophilic syndrome with multiorgan involvement secondary to infection with Toxocara canis in a 79-year-old Swiss female patient with a medical history of ischemic cerebrovascular insult and a curatively resected non-small-cell bronchial carcinoma, successfully treated with albendazole and steroids.

Helminths in Invasive Raccoons (Procyon lotor) from Southwest Germany

As hosts of numerous zoonotic pathogens, the role of raccoons needs to be considered in the One Health context. Raccoons progressively expand their range as invasive alien species in Europe. This study aimed to investigate the intestinal helminth fauna of raccoons in Baden-Wuerttemberg, Germany, as no such screening had ever been conducted there. In total, we obtained 102 animals from hunters in 2019 and 2020. Intestinal helminths were retrieved using the SSCT (segmented sedimentation and counting technique) and identified morphologically and by PCR-based Sanger sequencing. Fecal samples were assessed using the ELISA PetChek^TM IP assay (IDEXX, Germany) and flotation technique. The artificial digestion method was employed for analyzing muscle tissue. We detected species of four nematode genera (Baylisascaris procyonis, Toxocara canis, Capillaria spp., and Trichuris spp.), three cestode genera (Atriotaenia cf. incisa/procyonis, Taenia martis, and Mesocestoides spp.), and three trematode genera (Isthmiophora hortensis/melis, Plagiorchis muris, and Brachylaima spp.). Echinococcus spp. and Trichinella spp. were not found. The invasive behavior and synanthropic habits of raccoons may increase the infection risk with these helminths in wildlife, domestic and zoo animals, and humans by serving as a connecting link. Therefore, it is crucial to initiate additional studies assessing these risks.

Seroprevalence of human toxocariasis in Latin America and the Caribbean: a systematic review and meta-analysis

Introduction

The current study aimed to quantitatively synthesize available evidence regarding the seroprevalence of human toxocariasis in Latin America and the Caribbean.

Methods

A systematic research involving six electronic databases was conducted using a research strategy that combined MeSH terms with free terms. Article selection and information extraction were performed using a double and independent approach. The Newcastle-Ottawa tool was used to assess the risk of bias in the included articles. The meta-analysis used the random-effects approach, with subgroup analysis and sensitivity analysis for risk of bias also being performed.

Results

We included 101 articles with a total of 31,123 participants. The studies were conducted between 1990 and 2022, with Brazil accounting for the largest number of studies (n = 37). The overall seroprevalence of human toxocariasis was 31.0% (95% CI: 27.0-35.0%, I2 = 99%). The prevalence of the main characteristics observed in seropositive patients were as follows: ocular toxocariasis (30.0%), asymptomatic (26.0%), and presence of dogs at home (68.0%). In addition, the seroprevalence was lower in studies including only adults than in those including children or both. In contrast, no differences in seroprevalences were found between studies conducted in the community and hospital.

Conclusion

The overall seroprevalence of human toxocariasis in Latin America and the Caribbean was high. Notably, our findings showed that the seroprevalence was increased among populations who kept a dog at home but was decreased in populations comprising only adults. Our findings can be used to establish epidemiological surveillance strategies for the prevention and early identification of toxocariasis.

Dogs as a source for the spreading of enteric parasites including zoonotic ones in Giza Province, Egypt

To investigate the impact of domestic and stray dogs on the transmission of zoonotic and other parasites to humans in contact with them, fecal samples were collected from 80 domestic dogs that presented at a clinic with health disturbances and 220 randomly selected stray dogs housed in shelters. The parasitological examination of these samples revealed infection by six zoonotic and four non-zoonotic parasites in varying percentages. The zoonotic parasites included Ancylostoma caninum, Toxocara canis, Dipylidium caninum, Echinococcus granulosus, Cryptosporidium species, and Giardia cysts and trophozoites. The other parasites included Toxascaris leonina, Trichuris vulpis, Taenia species eggs, and Isospora canis oocysts. The infection rate was higher in stray dogs (60%) than in domestic dogs (40%). Infected dogs in both groups were generally unhealthy, with poor body condition recorded in 13.8% of domestic dogs and 63.6% of stray dogs. The infection rate was higher (92%) among shelter workers than among domestic dog owners (66.7%). Giardia assemblages A and D from dogs and assemblage A from humans, as well as two isolates of Cryptosporidium canis (C. canis), one from dogs and the other from humans, were submitted in the GenBank with the accession numbers OQ870443, OQ870444, and OQ919265 for Giardia and OQ917532 & OQ915519 for C. canis of dogs & human, respectively. In conclusion, domestic and stray dogs play an essential role in transmitting zoonotic parasites to humans in contact with them, and regular deworming and strict hygienic measures are recommended to minimize their impact on human health.

Application of Silver Nanoparticles in Parasite Treatment

Silver nanoparticles (AgNPs) are ultra-small silver particles with a size from 1 to 100 nanometers. Unlike bulk silver, they have unique physical and chemical properties. Numerous studies have shown that AgNPs have beneficial biological effects on various diseases, including antibacterial, anti-inflammatory, antioxidant, antiparasitic, and antiviruses. One of the most well-known applications is in the field of antibacterial applications, where AgNPs have strong abilities to kill multi-drug resistant bacteria, making them a potential candidate as an antibacterial drug. Recently, AgNPs synthesized from plant extracts have exhibited outstanding antiparasitic effects, with a shorter duration of use and enhanced ability to inhibit parasite multiplication compared to traditional antiparasitic drugs. This review summarizes the types, characteristics, and the mechanism of action of AgNPs in anti-parasitism, mainly focusing on their effects in leishmaniasis, flukes, cryptosporidiosis, toxoplasmosis, Haemonchus, Blastocystis hominis, and Strongylides. The aim is to provide a reference for the application of AgNPs in the prevention and control of parasitic diseases.

Toxocariasis in Ghanaian neighbourhoods: a need for action

Background

Animal reservoirs of Toxocara spp., a neglected parasitic infection, are frequently found in many Ghanaian neighbourhoods. Despite various interactions occurring between these animals and humans which sustain zoonosis, not much focus has been directed at disease surveillance in Ghana, necessitating this study.

Methods

The study was cross-sectional. It combined the collection of biological samples with the survey approach. The study used purposive and convenience sampling techniques to collect data from eligible participants in the Greater Accra region of Ghana. Besides the collection of biological samples from animals which were processed using molecular techniques, semi-structured questionnaires were administered to the pet owners.

Results

In sum, 32.2% (95% CI, 27.6%-37.0%) of the targeted animals were positive for Toxocara canis, with most of the cases being found in dogs and rodents. Among the 204 rodents, more Praomys tulbergi were positive for this parasite compared to the others. From the survey, some risk factors culminating in high disease exposure were identified: more than one-third of pet owners did not deworm their pets although about a fourth shared bed with them. In addition, many respondents' kids played with these pets but not all supervised them to practice hand hygiene. Also, a good number of pet owners confirmed the frequent exposure of their pets to rodents.

Conclusions

The relatively high prevalence of T. canis recorded in animals and the increasing exposure of humans to this parasite point to a higher risk for human toxocariasis. Furthermore, T. canis found in cats cannot be ignored and merits further investigations. For Ghana to achieve SDG 3 by 2030, priority must also be placed on neglected diseases which calls for an integrated approach to disease surveillance and a redirection of research focus using the one health concept.

Case report: Ultrasound biomicroscopy as a guide for the selection of injection sites for dexamethasone intravitreal implant (Ozurdex) for peripheral granulomatous ocular toxocariasis in children

Purpose

This article aims to report a case of successful treatment of peripheral granulomatous ocular toxocariasis (OT) in an 8-year-old patient using intravitreal injection of dexamethasone (DEX) implant (Ozurdex) under ultrasound biomicroscopy (UBM) guidance.

Case presentation

A previously healthy 8-year-old boy with a history of long-term close contact with dogs complained of blurring of vision in the right eye for a year. Ophthalmic examination of his right eye showed chronic uveitis. Notably, UBM examination identified granulomas and peripheral vitreous strand in the ciliary body from 3 to 8 o'clock positions. Enzyme-linked immunosorbent assay (ELISA) results of the intraocular fluid (IF) and serum showed increased anti-Toxocara immunoglobulin G (IgG) levels, leading to a diagnosis of peripheral granulomatous OT in the right eye. Intraocular surgery was not indicated in this case. The treatment goal was to alleviate uveitis, improve visual acuity, and prevent complications. He was treated with an intravitreal injection of DEX implant, administered as a single dose every three months, total two doses, combined with albendazole, an oral anthelmintic. Under preoperative UBM guidance, two injections were performed at the 12 and 10 o'clock positions in the pars plana where there were no granulomas and peripheral vitreous strand, successfully preventing complications associated with intravitreal injection. After two injections, the patient's right eye vision improved significantly, with the best-corrected visual acuity (BCVA) increasing from 20/400 to 20/50. Vitreous opacity and retinal edema were reduced, preretinal proliferative membrane was stabilized, and no adverse events occurred.

Conclusion

UBM can accurately determine the location and extent of peripheral granulomas in OT patients, facilitating the avoidance of granulomas during intravitreal injection and preventing complications associated with intravitreal injection. Under the close follow-up and strict adherence to indications, preoperative UBM-guided intravitreal injections of DEX implant treatment for pediatric peripheral granulomatous OT are safe and effective, providing a new therapeutic option for pediatric peripheral granulomatous OT.

Zoonotic Parasites in Playgrounds in Southern Spain: A One Health Approach

Zoonotic parasitic diseases are considered a global threat to public health. In this sense, canines and felines may be infected by different cosmopolitan parasites, with playgrounds serving as an important focus of infection for humans, as well as domestic or wild animals. Knowledge of the epidemiological situation of parasites in animal reservoirs integrated into the environment, identifying the spread pathways, is a key element for an effective response to this threat. Thus, the aim of this study was to assess the frequency of intestinal parasites with zoonotic potential in 120 playgrounds in the Malaga province (Spain). Samples were processed and analysed following standard parasitological procedures. Some 36.7% of playgrounds were parasite-positive with one or more zoonotic parasites. The most common parasites recovered were nematodes (60.0%), followed by protozoan species (33.3%) and cestodes (6.7%). In the parasite-positive playgrounds, Toxocara spp. (17.0 ± 3.5%) and Giardia duodenalis (17.0 ± 3.4%) were the most predominant parasites. In addition, 34.1% of playgrounds were infected with multiple parasites. Our results show a high presence of parasitic forms with zoonotic potential in playgrounds in Malaga, Spain. Due to the close contact between pets and humans in playgrounds, the potential zoonotic risk may increase if prevention and control measures are not designed.

Toward anthelmintic drug candidates for toxocariasis: Challenges and recent developments

Infections caused by parasitic helminths rank among the most prevalent infections of humans and animals. Toxocariasis, caused by nematodes of the genus Toxocara, is one of the most widespread and economically important zoonotic parasitic infections that humans share with dogs and cats. Despite the completion of the Toxocara canis draft genome project, which has been an important step towards advancing the understanding of this parasite and the search for drug targets, the treatment of toxocariasis has been dependent on a limited set of drugs, necessitating the search for novel anthelmintic agents, specially against Toxocara larvae in tissues. Given that research, development, and innovation are crucial to finding appropriate solutions in the fight against helminthiasis, this paper reviews the progress made in the discovery of anthelmintic drug candidates for toxocariasis. The main compounds reported in the recent years regards on analogues of albendazole, reactive quinone derivatives and natural produts and its analogues. Nanoparticles and formulations were also reviewed. The in vitro and/or in vivo anthelmintic properties of such alternatives are herein discussed as well as the opportunities and challenges for treatment of human toxocariasis. The performed review clarify that the scarcity of validated molecular targets and limited chemical space explored are the main bottlenecks for advancing in the field of anti-Toxocara agents.

Gray Wolf (Canis lupus italicus) and Red Fox (Vulpes vulpes) Parasite Survey in Anthropized and Natural Areas of Central Italy

Gastrointestinal nematodes and protozoa and other parasite occurrences were evaluated in free-ranging wolf (Canis lupus italicus) and red fox (Vulpes vulpes) populations from natural and anthropized areas of Central Italy. Analyzed fecal samples were collected from 60 foxes and 40 wolves in the anthropized areas, and 41 foxes and 39 wolves in the natural areas. In foxes, hookworm infections (p < 0.0001) were more frequently recorded in the anthropized environment, while coccidia (p < 0.05) and Cryptosporidium spp. (p < 0.0001) were more frequent in the natural area. In wolves, a higher frequency of hookworms (p < 0.0001) was observed in natural areas, while coccidia were more common in the anthropized area (p < 0.05). Moreover, in the natural environment, trichuroid nematodes (p < 0.0001) were significantly more frequent in wolves than in foxes, while Cryptosporidium (p < 0.001) and Giardia duodenalis (p < 0.001) were more common in foxes. In the anthropic area, the occurrence of hookworms was found to be significantly higher in foxes (p < 0.0001), while trichuroid nematodes were more common in wolves (p < 0.0001). The obtained data are indicative of a different diffusion of specific parasite taxa in wolves and foxes living in the natural and/or anthropized environments examined herein.

Potential roles of Toxocara canis larval excretory secretory molecules in immunomodulation and immune evasion

Toxocara canis larvae invade various tissues of different vertebrate species without developing into adults in paratenic host. The long-term survival of the larvae despite exposure to the well-armed immune response is a notable achievement. The larvae modulate the immune response to help the survival of both the host and the larvae. They skew the immune response to type 2/regulatory phenotype. The outstanding ability of the larvae to modulate the host immune response and to evade the immune arms is attributed to the secretion of Toxocara excretory-secretory products (TESPs). TESPs are complex mixture of differing molecules. The present review deals with the molecular composition of the TESPs, their interaction with the host molecules, their effect on the innate immune response, the receptor recognition, the downstream signals the adaptive immunity and the repair of tissues. This review also addresses the role of TESPs molecules in the immune evasion strategy and the potential effect of the induced immunomodulation in some diseases. Identification of parasite components that influence the nematode-host interactions could enhance understanding the molecular basis of nematode pathogenicity. Furthermore, the identification of helminths molecules with immunomodulatory potential could be used in immunotherapies for some diseases.

Altered miRNA Expression Profiles in the Serum of Beagle Dogs Experimentally Infected with Toxocara canis

Toxocara canis is a neglected roundworm, which can cause debilitating disease in dogs and humans worldwide. Serum is an excellent material for monitoring the occurrence of many diseases. However, no information is available on the expression of microRNAs (miRNAs) in the serum of dogs infected with T. canis. In this study, RNA-seq analysis was performed to identify the serum miRNA profiles in Beagle dogs infected with T. canis at different stages of infection. A total of 3, 25 and 25 differently expressed miRNAs (DEmiRNAs) were identified in dog serum at 24 h post-infection (hpi), 10 days post-infection (dpi) and 36 dpi, respectively, such as cfa-let-7g, cfa-miR-16, cfa-miR-92b, cfa-miR-93, cfa-miR-122, cfa-miR-485 and cfa-miR-451. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that these miRNAs could regulate the pathways related to parasitic infectious diseases and immune system, such as amoebiasis, toxoplasmosis, platelet activation, IL-17 signaling pathway and chemokine signaling pathway. These results provide a foundation to explore the underlying regulatory role of miRNAs in definitive hosts after T. canis infection.

Toxocarosis in humans: how much of a problem is it in the UK?

Toxocara canis (from dogs) is recognised as a potential cause of human toxocarosis, but Toxocara cati (from cats) and other species (eg, Toxascaris leonina found in foxes) are also possible causes. Most colonisation with Toxocara species does not lead to symptomatic infection in well-cared for adult animals; young and debilitated animals are at greater risk. Humans can acquire infection from infected animals, for example, via soil contaminated with faeces; however, most human infections are asymptomatic, with symptomatic infection being very rare in the UK. The risk of human infection is reduced by measures such as hand washing and responsible disposal of dog faeces. Some organisations recommend regular prophylactic treatment of pet dogs and cats. However, there are concerns that some parasiticides are contaminating the environment. As an example of a One-Health problem there is a potential conflict between the needs of animal health, human health and the health of the wider ecosystem. Also, considering that only about 5% of non-juvenile household dogs shed Toxocara eggs at a given time, it has been questioned whether it is worthwhile to invest in frequent blind treatments. British veterinary organisations have suggested less frequent treatment may be more appropriate and should be based on individual risk assessment and faecal examinations for worms rather than blanket regular prophylactic treatment, which could reduce the impact of parasiticides on the environment without greatly increasing the risks to animal or human health.

Gastrointestinal parasites in young dogs and risk factors associated with infection

Young dogs are particularly susceptible to infections with endoparasites. The occurrence of endoparasites was investigated in young dogs from Central Germany between July 2020 and July 2022. In total, 386 fecal samples originating from 171 dogs were examined for the prevalence of endoparasites using a combined flotation- and sedimentation technique and conventional PCR. Overall, in 41.2% (159/386) of the examined samples, endoparasites were detected. The most frequently occurring endoparasites were Giardia duodenalis (29%), Cryptosporidium spp. (9.1%), Cystoisospora spp. (7.3%), and Toxocara canis (6%). Sequencing of G. duodenalis positive samples showed that most infections belonged to the host-specific assemblages C (38.4% (43/112)) and D (35.7% (40/112)). The zoonotic assemblage A was identified in 8% (9/112) of the samples. Moreover, mixed infections were observed as follows: C/D in 5 (4.5%), D/A in 4 (3.6%), and C/A in 3 (2.7%) samples. All assemblage A infections were assigned to the potentially zoonotic subassemblage AI. Co-infections of G. duodenalis and Cryptosporidium spp. were observed in 3.1% (12/386) of the samples. Analyzing several host factors for their potential association with endoparasitic infection, the origin of dogs, as well as the living environment were identified as the main risk factors for infection with endoparasites. Overall, this study shows a high infection rate with endoparasites, especially G. duodenalis, in young dogs from Germany. The results of this study contribute to further insight into the distribution and potential risk factors associated with endoparasitic infections, as well as the zoonotic potential these parasites may present.

Prevalence of Toxocara canis infection in dogs and Toxocara egg environmental contamination in Baybay City, Leyte, Philippines

Toxocara canis is a parasitic gastrointestinal nematode of dogs causing toxocariasis in humans, a neglected tropical disease. This study examined the burden of T. canis infection in dogs and egg contamination in school playgrounds and public parks in Baybay City, Leyte, Philippines. Fecalysis and egg detection in soils were performed to determine the parasite prevalence in dogs and the environment. In addition, pet owner's survey and GIS mapping were employed to identify the risk factors of infection and map the parasite distribution. Fecalysis revealed a T. canis prevalence of 64.44% (95% CI: 48.78-78.13) at the barangay level and 17.96% (95% CI: 14.12-21.80) at the animal level. Rural areas showed a much higher T. canis prevalence than urban. Factors associated with high T. canis infection included dog's age, specifically puppy (2-8 mo) relative to young (> 8-24 mo) [Adjusted Odds Ratio (AOR): 2.282; 95% CI: 1.137-4.579; p = 0.020] and adult (> 24 mo) (AOR: 3.542; 95% CI: 1.714-7.319; p = 0.001), access to dirty water (AOR: 2.749; 95% CI: 1.575-4.798; p < 0.001), and non-deworming (AOR: 2.961; 95%: CI 1.009-8.684; p = 0.048). Furthermore, we observed high Toxocara egg contamination in school playgrounds and public parks, with a prevalence of 51.11% (95% CI: 35.77-66.3) at the barangay level and 15.45% (95% CI: 10.67-20.23) in soil samples. This epidemiological study is the first in the central Philippines to report a high burden of T. canis infection in dogs and the environment, thus providing crucial data that will help understand the epidemiology of toxocariasis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12639-022-01525-y.

Lung Lipidomic Alterations in Beagle Dogs Infected with Toxocara canis

Toxocariasis, mainly caused by Toxocara canis, and to a lesser extent, Toxocara cati, is a neglected parasitic zoonosis. The mechanisms that underlie the changes in lipid metabolism of T. canis infection in Beagle dogs' lungs remain unclear. Lipidomics is a rapidly emerging approach that enables the global profiling of lipid composition by mass spectrometry. In this study, we performed a non-targeted lipidomic analysis of the lungs of Beagle dogs infected with the roundworm T. canis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 1197 lipid species were identified, of which 63, 88, and 157 lipid species were significantly altered at 24 h post-infection (hpi), 96 hpi, and 36 days post-infection (dpi), respectively. This global lipidomic profiling identified infection-specific lipid signatures for lung toxocariasis, and represented a comprehensive comparison between the lipid composition of dogs' lungs in the presence and absence of T. canis infection. The potential roles of the identified lipid species in the pathogenesis of T. canis are discussed, which has important implications for better understanding the interaction mechanism between T. canis and the host lung.

Isolation and Production of Human Monoclonal Antibody Proteins against a Toxocara canis Excretory-Secretory Recombinant Antigen

Toxocariasis is a widespread zoonotic parasitic disease with a significant socioeconomic impact, particularly on underprivileged communities. Limitations of existing diagnostic tools and vague presenting symptoms may lead to misdiagnosis, thus underestimating the actual global impact of the disease. The present study describes the isolation and production of novel recombinant monoclonal antibodies against Toxocara canis recombinant TES-26 antigen (rTES-26) utilizing a human helminth scFv phage display library. The isolated antibody clones were characterized based on their gene sequences and binding characteristics. Three clones representing unique gene families (clone 48: IgHV3-LV1; clone 49: IgHV3-LV3; clone 50: IgHV6-LV3) were isolated, but only clones 48 and 49 showed successful insertion of the full-length scFv antibody sequence after sub-cloning. Both clones produced antibody proteins of good solubility and satisfactory yield and purity. Binding assays via Western blot and ELISA using rTES-26 and Toxocara canis native protein showed that both monoclonal antibodies were highly specific and sensitive to the target antigen. A preliminary antigen detection ELISA showed the diagnostic potential of the monoclonal antibody proteins. The proteins can also be useful in studying host−parasite interactions and therapeutic applications.

Serosurvey of anti-Toxocara canis antibodies in people experiencing homelessness and shelter workers from São Paulo, Brazil

BACKGROUND

Despite being one of the most prevalent helminth parasitic zoonoses worldwide and particularly in socioeconomically vulnerable populations, toxocariasis remains to be fully investigated in persons experiencing homelessness. Accordingly, the present study has aimed to assess the seroprevalence and associated risk factors of Toxocara spp. exposure in persons experiencing homelessness and shelter workers from a day-shelter in São Paulo city, Brazil.

METHODS

Anti-Toxocara IgG antibodies were detected by enzyme-linked immunosorbent assay (ELISA). Univariable and multivariable logistic regression models were performed to assess the risks for toxocariasis.

RESULTS

Overall, anti-Toxocara IgG antibodies were detected in 89/194 (45.9%, 95% CI: 39.0-52.9%) persons experiencing homelessness, twice as high (OR = 2.2; 95% CI = 1.245-3.873; P = 0.0089) than the frequency of 22/79 (27.8%, 95% CI: 19.2-38.6) in shelter workers. College education was the only protective factor for Toxocara spp. exposure (OR: 0.23; P = 0.018) revealed by logistic regression.

CONCLUSIONS

Although indicating a multifactorial origin of toxocariasis, the present study has assessed a highly vulnerable population with high disease risks and premature death. Thus, the living conditions of the homeless population have influenced the high prevalence of anti-Toxocara antibodies verified here compared with domiciled shelter workers. Despite being less exposed, shelter and other outdoor workers may present an occupational risk to toxocariasis. Future studies should establish whether such environmental exposure might occur in persons experiencing homelessness in other regions worldwide.

Differential Spleen miRNA Expression Profile of Beagle Dogs Infected with Toxocara canis

Toxocara canis is an unnoticed zoonotic helminth that causes severe disease in animals and humans. The spleen has a wide range of immunological functions in protecting the host against infection by many pathogens, but the function of the spleen in T. canis infection is still to be clarified, especially for the role of spleen microRNAs (miRNAs). In this study, deep sequencing of spleen RNA samples of 18 Beagle puppies was conducted to uncover the miRNAs expression profiling at 24 h post-infection (hpi), 96 hpi, and 36 days post infection (dpi). A total of 20, 34, and 19 differentially expressed miRNAs (DEmiRNAs) were identified at 24 hpi, 96 hpi, and 36 dpi, respectively. These DEmiRNAs (e.g., cfa-miR-206, cfa-miR-331, and cfa-miR-339) could play critical roles in Beagle puppies against T. canis infection, such as influencing inflammatory and immune-related cells and cytokines, by regulating target genes that are tightly associated with host immune function and enriched in immune response and immune pathways based on GO annotation and KEGG enrichment analysis. The current study discovered marked alterations of spleen miRNAs after T. canis infection, with potential effects on the pathogenesis of toxocariasis.

Lipidomic changes in the liver of beagle dogs associated with Toxocara canis infection

A global lipidomic analysis using liquid chromatography–tandem mass spectrometry was performed on the liver of beagle dogs infected with Toxocara canis to profile hepatic lipid species at 12 h post-infection (hpi), 24 hpi, and 36 days post-infection (dpi). This analysis identified six categories and 42 subclasses of lipids, including 173, 64, and 116 differentially abundant lipid species at 12 hpi, 24 hpi, and 36 dpi, respectively. Many of the identified lysophospholipids, such as lysophosphatidylglycerol, lysophosphatidylserine, and lysophosphatidylcholine, may contribute to the migration and development of T. canis during the early infection stage. Pathway analysis revealed significant alterations of several immune-inflammatory pathways, such as the B-cell receptor signaling pathway, the NF-kappa B signaling pathway, and the C-type lectin receptor signaling pathway at 12 and 24 hpi. These findings demonstrate the value of lipidomic profiling in revealing the extent of changes in the composition and abundance of hepatic lipidome caused by T. canis infection and their relevance to the pathophysiology of toxocariasis in beagle dogs.

Canine hepatic calodiosis with cirrhosis

The nematode parasite Calodium hepaticum (Capillaria hepatica) has a global distribution and is commonly reported in rodents (definitive host), dogs, cats and wild animals. Humans especially children are more susceptible to the parasitic infection. This paper documents an incidental finding of hepatic calodiosis with cirrhosis in a stray dog and discusses the zoonotic implications. A non descript dog was brought for necropsy examination to the Department of Veterinary Pathology, Madras Veterinary College, Tamil Nadu, India. Liver appeared dark brown, mottled with multifocal random variably sized, grey white flat firm areas. Histopathologically, liver tissue revealed multiple random encysted large collection of eggs surrounded by mild inflammation with a few lymphocytes, macrophages and fine fibrosis. The eggs had characteristic barrel shape, bipolar ends, bilayered wall, cross striations between the walls, and yolk. Periodic acid Schiff stain demonstrated the glycolic wall of ova. Marked portal to portal fibrosis was demonstrated by Masson's trichrome (for collagen) and by Warthin-Starry (for reticulin) stains. The stage of parasitic infection was diagnosed as intermediate to chronic due to fibrosis. A need to study the prevalence of the disease in rodents, human and animals is emphasized. Improper burial of carcasses of rodents and dogs may contribute to spread of infection. Pets and stray animals may transmit infection to human and pose health risk.

Ocular surface microbiota: Ophthalmic infectious disease and probiotics

Recently, increasing studies have emphasized the importance of commensal bacteria in humans, including microbiota in the oral cavity, gut, vagina, or skin. Ocular surface microbiota (OSM) is gaining great importance as new methodologies for bacteria DNA sequencing have been published. This review outlines the current understanding and investigation of OSM and introduces the new concept of the gut–eye axis. Moreover, we have collected current studies that focus on the relationship between ophthalmic infectious disease and alterations in the OSM or human gut microbiota. Finally, we discuss the current application of probiotics in ophthalmic infectious disease, its limitations to date, and futural directions.

RNA sequencing reveals dynamic expression of spleen lncRNAs and mRNAs in Beagle dogs infected by Toxocara canis

BACKGROUND

Toxocara canis is a cosmopolitan parasite with a significant adverse impact on the health of humans and animals. The spleen is a major immune organ that plays essential roles in protecting the host against various infections. However, its role in T. canis infection has not received much attention.

METHODS

We performed sequencing-based transcriptome profiling of long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression in the spleen of Beagle puppies at 24 h post-infection (hpi), 96 hpi and 36 days post-infection (dpi). Deep sequencing of RNAs isolated from the spleen of six puppies (three infected and three control) at each time point after infection was conducted.

RESULTS

Our analysis revealed 614 differentially expressed (DE) lncRNAs and 262 DEmRNAs at 24 hpi; 726 DElncRNAs and 878 DEmRNAs at 96 hpi; and 686 DElncRNAs and 504 DEmRNAs at 36 dpi. Of those, 35 DElncRNA transcripts and 11 DEmRNAs were detected at all three time points post-infection. Many DE genes were enriched in immune response, such as ifit1, ifit2 and rorc. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that some genes (e.g. prkx and tnfrsf11a) were involved in the T cell receptor signaling pathway, calcium signaling pathway, Ras signaling pathway and NF-κB signaling pathway.

CONCLUSIONS

The findings of this study show marked alterations in the expression profiles of spleen lncRNAs and mRNAs, with possible implications in the pathophysiology of toxocariasis.

N-(4-Methoxyphenyl)Pentanamide, a Simplified Derivative of Albendazole, Displays Anthelmintic Properties against the Nematode Toxocara canis

Infections caused by parasitic helminths have enormous health, social, and economic impacts worldwide. The treatment and control of these diseases have been dependent on a limited set of drugs, many of which have become less effective, necessitating the search for novel anthelmintic agents. In this study, a simplified compound, N-(4-methoxyphenyl)pentanamide (N4MP), based on the structure of the most widely used anthelmintic (albendazole), was chemically prepared using 4-anisidine and pentanoic acid. N-(4-Methoxyphenyl)pentanamide was evaluated in vitro against the nematode Toxocara canis, an ascarid roundworm of animals that can infect humans. Similar to albendazole, bioassays showed that N-(4-methoxyphenyl)pentanamide affected the viability of parasites in a time- and concentration-dependent manner. Interestingly, N-(4-methoxyphenyl)pentanamide showed a profile of lower cytotoxicity to human and animal cell lines than albendazole. Pharmacokinetic, drug-likeness, and medicinal chemistry friendliness studies demonstrated an excellent drug-likeness profile for N-(4-methoxyphenyl)pentanamide as well as an adherence to major pharmaceutical companies’ filters. Collectively, the results of this study demonstrate that the molecular simplification of albendazole to give N-(4-methoxyphenyl)pentanamide may be an important pipeline in the discovery of novel anthelmintic agents.

IMPORTANCE Infections caused by parasitic helminths have enormous health, social, and economic impacts worldwide. The treatment and control of these diseases have been dependent on a limited set of drugs, many of which have become less effective, necessitating the search for novel anthelmintic agents. Considering this scenario, the present study reports the preparation of N-(4-methoxyphenyl)pentanamide (N4MP), a simplified molecule based on the structure of the most widely used anthelmintic (albendazole). N4MP was evaluated in vitro against the nematode Toxocara canis, a common ascarid roundworm of domestic animals that can infect humans. Similar to albendazole, bioassays showed that N4MP affected the viability of parasites in a time- and concentration-dependent manner but displayed a profile of lower cytotoxicity to human and animal cell lines than albendazole. Therefore, this study demonstrates that the molecular simplification of albendazole to give N4MP may be an important pipeline in the discovery of novel anthelmintic agents.

Toxocara canis Infection Alters mRNA Expression Profiles of Peripheral Blood Mononuclear Cells in Beagle Dogs at the Lung Infection Period

Simple Summary

Toxocariasis is one of the most neglected zoonoses in the world. Toxocara canis is the main pathogen causing toxocariasis in humans and animals, threatening public health. To date, the mechanism by which the larvae of T. canis escape the attack of immune cells in the blood is still poorly understood. Using RNA-seq technology, the transcriptional alterations of Beagle dog peripheral blood mononuclear cells (PBMCs) between the presence and absence of T. canis infection were analyzed during the lung infection period, and 1066 upregulated genes and 1076 downregulated genes were identified (padj < 0.05 and |log₂ (FoldChange)| > 1). In addition, many immune- or inflammation-related GO terms and KEGG signaling pathways were significantly altered during T. canis infection by GO annotation and KEGG enrichment analysis. The present study revealed that T. canis infection can alter the mRNA profiles of PBMCs in Beagle dogs during the lung infection period, which has important implications for a better understanding of the interaction mechanism between T. canis and host immune cells.

Abstract

Toxocara canis is a neglected zoonotic roundworm distributed all over the world, causing toxocariasis in humans and animals. However, so far, the immune mechanism of T. canis infection in definitive hosts remains to be clarified. In this study, the transcriptional alterations of Beagle dogs’ peripheral blood mononuclear cells (PBMCs) induced by T. canis infection during the lung infection period were analyzed using RNA-seq technology. A total of 2142 differentially expressed genes were identified, with 1066 upregulated genes and 1076 downregulated genes. Many differentially expressed genes participated in the biological process of intracellular signal transduction, as well as the immune- or inflammation-related KEGG signaling pathway, such as the Notch signaling pathway, Toll-like receptor signaling pathway, and NF-kappa B signaling pathway, through KEGG enrichment analysis. This study indicated that T. canis infection could suppress the biological function of Beagle dogs’ PMBCs and provided basic data to further clarify the interaction mechanism between T. canis and host immune cells.

Changes in the expression of miR-103a and miR-21: a functional diagnosis of toxocariasis in rats

Introduction. Toxocariasis is a zoonotic parasitic disease caused by migrating nematode worms, Toxocara species larvae, within tissues. MicroRNAs (miRNAs) are small RNA molecules that regulate gene expression at a post-transcriptional level.Hypothesis/Gap Statement. miRNA-based diagnostic biomarkers for toxocariasis are emerging, but there is limited information about the role of many miRNAs and a more detailed diagnostic evaluation of miRNA expression patterns is needed to understand their immunobiological function.Aim. We investigated the expression levels of circulating miRNA 21 and miRNA 103a as potential biomarkers for the prediction and diagnosis of toxocariasis in Wistar rats infected with Toxocara canis.Methodology. Thirty Wistar rats were inoculated orally with 2500 T. canis embryonated eggs via gavage. Serum samples were collected from infected animals and were tested against T. canis antigens for 60 days post-infection. The plasma samples were isolated for quantitative real-time PCR (qPCR) assays and qPCR was used to assess transcription levels of miRNA 21 and miRNA 103a.Results. The prevalence of anti-Toxocara IgG was detected in 7/30 (23.3 %) infected rats. Molecular analysis of miRNAs 21 and 103a showed that expression levels of miRNAs in both groups of Toxocara-positive and negative samples were the same without significant association. The ratio of housekeeping gene expression (U6) to gene expression of miRNAs 21 and 103a indicated the rate of change (1/1.38 ≈ 0.75 and 1/0.751 ≈ 1.3, respectively).Conclusion. Our study revealed that miRNAs 21 and 103a might play fundamental roles as biomarkers and diagnostic tools for toxocariasis. However, the changes in expression of these miRNAs were not adequate to be used as biomarkers in diagnosis.

Cytokine Profile in Aqueous Humor of Patients With Ocular Toxocariasis

Purpose

Ocular toxocariasis (OT) is a vision-threatening disease with a largely unknown intraocular pathogenesis. Herein, we determined the cytokine expression profile in aqueous humor (AH) of patients with OT.

Methods

This is a retrospective case-control study of cytokine levels in AH of patients with OT and uveitis and control subjects. Thirty samples from eyes with OT, 23 from eyes with non-OT uveitis, and 25 from eyes with age-related cataract were analyzed using a multiplexed magnetic bead immunoassay. Thirty-one cytokines were detected and classified into 5 categories: T-helper type 1 (Th1) -associated cytokines, Th2-associated cytokines, Th17 cytokine, proinflammatory mediators, and growth factors.

Results

In the 31 cytokines, 9 cytokines were undetectable, including IL-1a, IL-1b, IL-2, IL-3, IL-12p70, IL-17A, TGF-a, TNF-β, and IFN-g. From the 22 cytokines, 13 exhibited significantly increased expression in the OT group than in the control group, including TNF-a, IFN-a2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-13, sCD40L, PDGF-AA, PDGF-AB/BB, FLT3l, and EGF. There were 5 cytokines exhibited significantly increased expression in the OT group than in non-OT group, including IL-5, IL-9, IL-10, IL-13, and PDGF-AA. There was no significantly decreased expression in any cytokines in the OT group when compared with control or non-OT groups. To the 5 cytokines that showed significant difference in OT group alone, IL-10 and IL-13 exhibited more than 13-fold increase, and IL-5 showed the most obvious as 27-fold increase in OT patients, when compared with that in control group.

Conclusion

The cytokine profile expression in aqueous humor from patients with ocular toxocariasis was investigated, and our findings suggest that Th1 and Th17 cytokine responses are not enhanced, whereas the cytokine status was polarized toward a Th2 response. Our findings also suggest the involvement of IL-5, IL-10, and IL-13 in the immunopathogenesis of ocular toxocariasis.

A Case Report of Intravitreal Dexamethasone Implant with Exudative Retinal Detachment for Ocular Toxocariasis Treatment

Toxocariasis is one of the most common geohelminth infections in several parts of the world. We describe a rare case of ocular toxocariasis with secondary exudative retinal detachment treated with albendazole and an intravitreal dexamethasone implant. A 13-year-old boy with counting finger vision was diagnosed with retinal vasculitis and exudative retinal detachment in his right eye. Fundoscopic examination revealed retinal hemorrhage, retinal vasculitis, and exudative retinal detachment. Serological test using serum and intraocular aqueous humor were positive for anti-Toxocara specific IgG antibodies. He received repeated doses of intravitreal dexamethasone implants combined with oral albendazole. A sequential follow-up optical coherence tomography revealed that the retina was successfully reattached. His visual acuity subsequently improved to 20/400.

Screening for parasites in migrant children

BACKGROUND

Globalization has pushed population movements in the last decades, turning imported diseases into the focus. Due to behavioral habits, children are at higher risk of acquiring iparasitosis. This study aims to investigate the prevalence of parasites in migrant children and factors associated with parasitic diseases.

METHOD

Retrospective cross-sectional study (2014-2018) including children diagnosed with parasitosis. The diagnosis was based on serology and/or microscopic stool-sample evaluation. Epidemiological and clinical data were recorded.

RESULTS

Out of 813 migrant children screened, 241 (29.6%) presented at least one parasite, and 89 (10.9%) more than one. The median age was 6.6 years (IQR: 3.1-11.9) and 58.9% were males. Most cases were referred for a health exam; only 52.3% of children were symptomatic, but 43.6% had eosinophilia. The most common diagnosis were giardiasis (35.3%), schistosomiasis (19.1%), toxocariasis (15.4%), and strongyloidiasis (9.1%). After the multivariate analysis, African origin and presenting with eosinophilia were the main risk factors for parasitism.

CONCLUSIONS

parasitosis are frequent among migrant children. Children are often asymptomatic, and thus active screening for parasitosis should be considered among high-risk populations. Eosinophilia can be useful to guide complimentary tests, as well as geographical origin, but normal eosinophil count does not exclude parasitosis.

Detection of Toxocara cati Larvae in a Common Buzzard (Buteo buteo) and in a Red Kite (Milvus milvus) in Basilicata Region, Italy

Toxocara cati is a common parasite of wild and domestic felines,and presents a cosmopolitan distribution. Adult parasites localize in the gut of the definitive host giving rise to the infection, which usually runs asymptomatic. These worms produce eggs that are excreted with feces into the environment, where they become a source of infection for paratenic hosts, such as mammals, birds, and invertebrates. In this brief communication, we report the detection of T. cati larvae in a common buzzard (Buteo buteo) and a red kite (Milvus milvus), in the Basilicata Region of Italy. This result may be important to define new pathways of spread and survival of T. cati in the wild.