Laboratory diagnosis of human toxocariasis. Vet Parasitol. 2013;193:327-336. [PMID: 23318165 DOI: 10.1016/j.vetpar.2012.12.028]

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.

First use of tissue exudate serology to identify Toxocara spp. infection in food animals

Toxocara canis and Toxocara cati are globally distributed, zoonotic roundworm parasites. Human infection can have serious clinical consequences including blindness and brain disorders. In addition to ingesting environmental eggs, humans can become infected by eating infective larvae in raw or undercooked meat products. To date, no studies have assessed the prevalence of Toxocara spp. larvae in meat from animals consumed as food in the UK or assessed tissue exudates for the presence of anti-Toxocara antibodies. This study aimed to assess the potential risk to consumers eating meat products from animals infected with Toxocara spp. Tissue samples were obtained from 155 different food producing animals in the south, southwest and east of England, UK. Tissue samples (n = 226), either muscle or liver, were processed by artificial digestion followed by microscopic sediment evaluation for Toxocara spp. larvae, and tissue exudate samples (n = 141) were tested for the presence of anti-Toxocara antibodies using a commercial ELISA kit. A logistic regression model was used to compare anti-Toxocara antibody prevalence by host species, tissue type and source. While no larvae were found by microscopic examination after tissue digestion, the overall prevalence of anti-Toxocara antibodies in tissue exudates was 27.7%. By species, 35.3% of cattle (n = 34), 15.0% of sheep (n = 60), 54.6% of goats (n = 11) and 61.1% of pigs (n = 18) had anti-Toxocara antibodies. Logistic regression analysis found pigs were more likely to be positive for anti-Toxocara antibodies (odds ration (OR) = 2.89, P = 0.0786) compared with the other species sampled but only at a 10% significance level. The high prevalence of anti-Toxocara antibodies in tissue exudates suggests that exposure of food animals to this parasite is common in England. Tissue exudate serology on meat products within the human food chain could be applied in support of food safety and to identify practices that increase risks of foodborne transmission of zoonotic toxocariasis.

Migratory pattern of zoonotic Toxocara cati and T. canis in experimentally infected pigs

BACKGROUND

Over a billion people are infected with Toxocara canis or T. cati, the roundworms of dogs and cats. Historically, T. canis has been considered the main species responsible for human toxocarosis, but as serodiagnosis cannot discriminate between the two species, this remains unresolved. We used pigs as a relevant large animal model for human infection to assess the migratory pattern of T. cati and T. canis.

METHODS

Pigs were inoculated with T. cati or T. canis eggs or PBS (negative controls) and necropsied 14 or 31 days later. Different organs and tissues were examined for parasites and pathological changes.

RESULTS

Overall, the two parasite species had a similar migration pattern reaching multiple organs and tissues, including the mesenteric lymph nodes, liver, lungs, and diaphragm. We recovered larvae of both species in the brain, suggesting that T. cati also can cause neurological toxocarosis in humans. Both species induced systemic eosinophilia and histopathological changes in the lungs, livers, and mesenteric lymph nodes.

CONCLUSION

This study emphasises the importance of T. cati as a zoonotic agent and the need to develop diagnostic methods that can differentiate between sources of infection in humans.

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.

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.

One health approach to toxocariasis in quilombola communities of southern Brazil

BACKGROUND

Toxocariasis has been listed among the most neglected parasitic diseases worldwide, with approximately one fifth of the global population exposed, particularly those living under poverty. In Brazil, communities of descendants of enslaved blacks (quilombola) have historically had some of the highest rates of vulnerability and poverty, characterized by lack of health assistance, poor quality of life, and nutritional insecurity.

METHODS

A cross-sectional sampling of quilombola individuals living in four communities of southern Brazil, as well as their dogs and the soil, was carried out from December 2021 to March 2022. Sociodemographic and other information such as water source, alimentary habits, and dog and cat ownership were gathered using a semi-structured questionnaire for assessing toxocariasis risk factors. Human serum samples were tested by ELISA for anti-Toxocara spp. IgG antibody detection was carried out on dog feces and hair, and soil samples were surveyed for presence of Toxocara spp. eggs.

RESULTS

Overall, 172/208 individuals (82.7%, 95% CI = 77.0-87.2) were seropositive, the highest seroprevalence rate to date in Brazil. Male gender (P = 0.029), educational level (P = 0.026), and drinking water source (P = 0.043) were associated with seropositivity by univariate analysis. Final logistic regression revealed increased odds (P = 0.017, OR = 7.6, 95% CI = 1.5-42.7) to have seropositivity in individuals > 50 years old (< 10 years old). As expected, individuals with soil contact were more likely seropositive (P = 0.038, OR = 4.4, 95% CI = 1.1-18.8). Although retrieved in only 5/96 (5.2%) dog feces, Toxocara spp. eggs were found in 18/60 (30.0%) soil samples.

CONCLUSIONS

The high vulnerability and seroprevalence observed in quilombola communities clearly demand a One Health approach for detection, monitoring, and prevention of infection by Toxocara spp. in both human and dog populations.

One health approach to toxocariasis in Brazilian indigenous populations, their dogs, and soil contamination

Introduction

Although socioeconomic vulnerability and lifestyle factors may contribute to the transmission of Toxocara spp., no study has investigated indigenous populations in Brazil using the One Health approach.

Methods

Accordingly, this study assessed anti-Toxocara spp. antibodies in Brazilian indigenous people and healthcare professionals by enzyme-linked immunosorbent assay. Presence of Toxocara spp. eggs (feces and hair) in dogs as definitive hosts and in soil samples of the indigenous communities were also recovered and molecularly investigated.

Results

Overall, 342/463 (73.9%) indigenous individuals and 46/147 (31.3%) non-indigenous healthcare professionals were seropositive for Toxocara spp. In addition, T. canis eggs were retrieved from 9/194 (4.6%) dog fecal samples and 4/204 (2.0%) dog hair samples, mainly from the Paraná State communities (3/42; 7.1%). Soil contamination was observed only in the Paraná State communities (36/90; 40.0%), with the molecular detection of T. canis. River water consumption was also associated with indigenous seropositivity (Odds ratio, 11.4).

Discussion

Indigenous individuals in Paraná State communities were 2.72-fold more likely to be seropositive than those in São Paulo State, likely due to a lack of sanitary infrastructure. In this scenario, a primarily soil-transmitted disease may also have become waterborne, with embryonated eggs probably spread to water supplies by rain. Full-time healthcare professionals in daily contact with indigenous communities were 9.2-fold more likely to be seropositive than professionals who visited sporadically, suggesting exposure to Toxocara spp. during their work and raising health concerns. In addition, the findings herein showed a significantly higher seroprevalence in indigenous people than in healthcare workers (χ2 = 85.5; p < 0.0001), likely due to overtime exposure to Toxocara spp. In conclusion, Brazilian indigenous communities are highly exposed to toxocariasis, with poor infrastructure and contact with contaminated river water as associated risk factors and a higher risk of infection in healthcare professionals working full-time in these communities.

Deglycosylation of Excretory-Secretory Antigens of the Second-Stage Larvae of Toxocara cati Improves Its Efficacy in the Diagnosis of Human Toxocariasis

Background

Toxocariasis is an important zoonotic infection, especially in tropical areas. One of the significant challenges in the serodiagnosis of human toxocariasis is the cross-reaction of Toxocara antigens with other parasites due to their relatively similar glycan structures. Removing the glycan structure from Toxocara excretory-secretory (TES) antigens may increase the efficacy of these antigens in the diagnosis of toxocariasis. The current study aimed to assess the efficacy of deglycosylated Toxocara cati excretory-secretory (dTES) antigens for the serodiagnosis of human toxocariasis.

Methods

Toxocara ES antigens were prepared from T. cati second-stage larvae and deglycosylated using sodium hydroxide (NaOH). The TES antigens, along with the dTES antigens, were used in an ELISA as well as a western blotting system for the detection of anti-Toxocara antibodies. Sera samples collected from 30 confirmed cases of toxocariasis, 30 patients with other diseases, and 30 healthy subjects were evaluated by both systems.

Results

The sensitivity of TES and dTES ELISA for the diagnosis of human toxocariasis was 96.67% (95% CI = 82.78-99.92) and 93.33% (95% CI = 77.93-99.18), respectively, while the specificity of dTES (88.33%; 95% CI = 77.43-95.18) increased significantly compared to the TES (80.00%; 95% CI = 67.67-89.22). The sensitivity of both antigens was 100% (95% CI = 88.43-100) by the western blotting system. Moreover, the specificity of TES and dTES antigens was 95% (95% CI = 86.08-98.96) and 98.33% (95% CI = 91.06-99.96), respectively, when using the western blotting system.

Conclusion

Results of the current study indicate that the chemical removal of the glycan epitopes of T. cati ES antigens significantly reduces cross-reactivity rates with other parasitic infections. Considering the findings of the present study, the dTES antigens seem to be suitable antigens for the serodiagnosis of human toxocariasis.

Intestinal helminthic infections: a narrative review to guide the hepatogastroenterologist

Intestinal helminthic infections are not uncommon in Western Europe, mainly due to modern travel, emigration and globalization. Moreover, some helminthic infections are endemic in Western Europe and are part of the everyday clinical practice. The hepatogastroenterologist should therefore recognize and manage these patients or at least refer them to appropriate reference centers. Signs and symptoms are often unspecific or even absent. Discerning the disease at an early stage avoids expensive diagnostic testing, life-threatening complications and in some cases even further spread of the disease. This review article aims to guide the hepatogastroenterologist when suspecting a helminthic infection by addressing the most prevalent symptoms, summarizing the most probable associated helminthic entities, highlighting practical steps in diagnosis and available treatments.

Evaluation of new Toxocara canis chimeric antigens as an alternative to conventional TES-Ag for anti-Toxocara antibodies detection

Human toxocariasis is one of the neglected helminthiases and it is caused by the zoonotic roundworm species Toxocara canis and Toxocara cati. Diagnosis of human toxocariasis is based on the combination of clinical, parasitological, and epidemiological criteria, as well as serology tests that detect anti-Toxocara antibodies. Notwithstanding, due to the absence of pathognomonic symptoms and signs of the disease, serology is the key evidence to support a conclusive diagnosis. TES-ELISA is the most widely used serological test for diagnosis. However, cross-reaction of TES antigens with antibodies produced to other helminth antigens is a major drawback for its application in countries with high parasitic prevalence. T. canis recombinant antigens have been described as an alternative to native TES for diagnosis. Nevertheless, the selection of antigenic proteins is a complex process that requires validation. In this paper, we developed an eGFP carrier-based system to express and purify blocks of recombinant polypeptides of T. canis antigenic proteins. Intense cross-reaction polypeptides were detected by Immunoblot and avoided to finally produce a chimeric prototype protein. Additionally, a control chimeric protein that harbors the complete tested proteins was produced. Purified chimeric antigens were tested in ELISA and Immunoblot assays with 310 sera samples of negative and positive control individuals. Our results showed that chimeric rCHITC0 and rCHITC1 antigens (with sensitivities of 62% 58%, 38% and 16% in IB-rCHITC0, ELISA-rCHITC0, ELISA-rCHITC1 and IB-rCHITC1 respectively for OLMS) can perform better in terms of specificity (being 91%, 89%, 87% and 76% for ELISA-rCHITC1, IB-rCHITC1, ELISA-rCHITC0 and IB-rCHITC0 respectively for OLMS) than T. canis TES-ELISA (with 61% specificity), giving a higher signal with serum samples of infected individuals as well the possibility to discriminate false positive cases with other parasitic infections. Our data suggest that T. canis chimeric proteins, represent candidate antigens for phase II studies.

Cyclosporine A increases the intensity of Toxocara canis infection in swiss mice

Toxocariasis is a zoonotic disease of worldwide distribution. The connection between parasitic diseases and conditions that depress the immune system, such as the use of immunosuppressive drugs, has been studied. The purpose of this study was to evaluate the effect of Cyclosporine A (CsA) on the intensity of infection, humoral response and gene transcription of interleukins IL-4, IL-10 and IL-12 in mice experimentally infected with Toxocara canis. To this end, mice were divided into two groups treated with CsA (G1: 10 mg/Kg and G2: 50 mg/kg), the G3 and G4 group received PBS. After the last administration of the drug or PBS (orally every 48 hours for 15 days), groups G1, G2 and G3 were inoculated with 1200 eggs of T. canis. Was collected blood samples on days zero, 15 and 30 days post-inoculation (PI), for ELISA test and the mice were euthanized 30 days PI. The organs and striated muscle tissue were collected for the recovery of larvae. The splenocytes were analyzed by RT-PCR. The intensity of infection in the mice treated with 50 mg/kg of CsA was 65.5% higher than in the control group (p=0.001). An analysis of the kinetics of anti-Toxocara antibody revealed that the groups treated with CsA showed significantly higher mean levels of antibodies on day 15 PI. The transcription of the three tested interleukins showed no statistical difference between G2 and G3 (control). It was concluded that the immunosuppression triggered by CsA (50 mg/Kg) favored the establishment of a larger number of T. canis larvae without, however, altering immunoglobulin production and IL-4, IL-10 and IL-12 transcription on day 30 PI.

A Retrospective Study of the Efficacy of Albendazole and Diethylcarbamazine for the Treatment of Human Toxocariasis

In the Department of Parasitology and Mycology of Toulouse University Hospitals, patients presenting with common/covert toxocariasis were treated either with albendazole (39 cases) or with diethylcarbamazine (32 cases). Albendazole (ABZ) was given at 10 mg/kg b/w daily for 14 days, and diethylcarbamazine (DEC) was given at 4 mg/kg b/w daily for 21 days. In both groups, follow-up consultations occurred approximately 48 days after the end of the anthelmintic therapy. ABZ and DEC displayed a similar efficacy on the kinetics of the clinical picture (−64.5% of reduction vs. −72.7%, respectively) and on the levels of blood eosinophilia, serum eosinophil cationic protein and serum total IgE. However, the effect of the medication on the laboratory parameters was moderate. The rate of adverse reactions was similar in both groups (38% for ABZ vs. 31% for DEC), but DEC-treated patients complained of more intense and long-lasting side effects. The DEC group had more major adverse reactions, resulting in the termination of the anthelmintic treatment. The results from this retrospective study bring further arguments for considering ABZ, given at 10 mg/kg daily for 2 weeks, as the drug of choice in the treatment of human toxocariasis.

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.

Therapy and Prevention for Human Toxocariasis

For the last four decades, knowledge about human toxocariasis with regard to its epidemiology, pathophysiology, clinical spectrum, and imaging or laboratory diagnosis has substantially progressed. Knowledge about specific therapy with anthelmintics has lagged behind. To date, only four drugs are registered for human use, and their efficacy has rarely been assessed in prospective controlled trials. It is likely that the repurposing of potent anthelmintics from veterinary medicine will improve this situation. Due to its wide availability and a lack of major side effects during short regimens, albendazole has become the drug of choice. However, its efficacy should be more precisely assessed. The role of anthelmintics in the treatment of neurological or ocular toxocariasis remains to be clarified. Prophylactic measures in humans or companion animals are efficient and represent first-line treatments for the control of this zoonosis. Unfortunately, their implementation in areas or countries where toxocariasis epidemiology is driven by poverty is quite difficult or unrealistic.

Longitudinal assessment of the exposure to Ascaris lumbricoides through copromicroscopy and serology in school children from Jimma Town, Ethiopia

Background

We previously demonstrated that serology holds promise as an alternative diagnostic tool to copromicroscopy to monitor and evaluate deworming programs targeting soil-transmitted helminths (STHs). Here we explored the dynamics of anti-Ascaris antibodies (Ab) and evaluated the Ab-isotype of choice to assess the longitudinal exposure to Ascaris in Ethiopian school children.

Methodology

Between October 2018 and February 2020, stool and blood samples were collected every four months from school children (4 to 6 years of age). Stool samples were analyzed by duplicate Kato-Katz to assess the presence and intensity of any STH infection. Plasma Ab-responses against the total extract of Ascaris suum lung third stage larvae were measured through in-house Ab-ELISA’s for seven different Ab-isotypes.

Principal findings

At baseline, 42.4% of the 66 children were excreting eggs of any STH, Trichuris (37.9%) being the most prevalent. The cumulative prevalence (proportion of children tested that positive at least once over the entire study period) was 56.1% for Trichuris and 31.8% for Ascaris. For Ascaris, re-infections were frequently observed, whereas for Trichuris, children often remained excreting eggs following drug administration. When measuring anti-Ascaris Ab-levels, the cumulative seroprevalence was generally higher (IgG4: 60.6%; IgG1: 50.0%; IgE: 36.4%). The individual anti-Ascaris IgG4 levels at baseline were positively associated with the fecal egg counts averaged over the study period, the rate of egg-appearance and the number of positive test results. There was no apparent cross-reactivity between the anti-Ascaris IgG4 Ab-ELISA and Trichuris.

Conclusions/Significance

We demonstrate that the children are exposed to STH before the age of four and that the exposure to Ascaris is underestimated when measured with copromicroscopy. Compared to other Ab-isotypes, IgG4 is the Ab-isotype of choice to measure Ascaris exposure in STH endemic settings. Finally, the results also highlight that measuring anti-Ascaris IgG4 levels holds promise as a tool to identify individuals at higher risk for continued exposure to this STH.

World-wide large-scale deworming programs are being implemented to control the morbidity attributable to intestinal worms. Our group has recently shown that diagnostic tools that detect anti-parasite antibodies hold promise as an alternative to the current diagnostic standard (detecting worm eggs in stool using microscopy) to monitor and evaluate the progress of these programs towards the set targets. In the present study, we further explored the potential of antibody-based assays by monitoring the exposure of Ethiopian school children during a 17-month period to worm infections. Our results indicated that children in this area are exposed to intestinal worms from an early age onwards and that, based on serological results, more children are exposed to worm infections than measured by the current diagnostic standard. In addition, we demonstrated that test results of the antibody assay at the start of the study were positively associated with mean egg counts averaged over the study period, the rate of egg-appearance and the number of positive stool tests, highlighting that such assay holds promise as a tool to identify individuals at higher high risk for continued exposure to worms, and ultimately improve control programs.

Two trichinellosis outbreaks in Serbia – challenging diagnosis due to a potential co-infection with Toxocara spp

In Serbia, in most cases, small family outbreaks of trichinellosis occur due to the consumption of untested infected meat from domestic pigs that are raised and slaughtered in the backyards of small individual farms. The aim of this study is to present data regarding 24 patients involved in two outbreaks that occurred in two neighbouring districts in Serbia during a closely related period of time in August 2014. The source of infection in the first outbreak was undercooked pork, while raw pork sausages caused the second outbreak. Meat samples and sausages were Trichinella spp. positive by artificial digestion. With the aim to obtain a second opinion and validate the serological findings discovered at the Public Health Institute Nis, all samples were sent to the National Reference Laboratory for Trichinellosis, INEP. Serodiagnosis showed that 21 persons were positive (87.5%) and three (12.5%) were negative for anti-Trichinella antibodies, while 15 patients fulfilled the trichinellosis case definition. Western blot analysis (using an epitope unique for the muscle larvae stage of the Trichinella genus) confirmed the diagnosis of trichinellosis in five patients. Six patients also had specific antibodies against Toxocara canis (T. canis). Due to the fact that in endemic foci in Serbia there is the presence of Trichinella spiralis and T. canis and that these two infections could be asymptomatic, we consider that trichinellosis cases were irrefutably proven. The dilemma about the existence of co-infection with T. canis remained open due to the lack of clinical findings.

Toxocara canis 30-35 kDa excretory-secretory antigen is an important marker in mice challenged by inocula containing different parasite load levels

The Western-blotting technique was applied to identify antigenic fractions of excretory-secretory Toxocara canis antigen recognized by IgG antibodies throughout an experimental infection in mice challenged by different inocula. Mice were inoculated with 5, 50 and 500 embryonated eggs and serum samples were collected 15, 30, 60, 90 and 120 days post-infection. Serum samples were analyzed using an excretory-secretory Toxocara antigen. Antibodies recognized antigenic fractions from 30 to 90 kDa. The protein fraction of 30-35 kDa was the most frequently recognized regardless of the size of inoculum and the stage of infection represented by the different collection times, but the antigenic recognition was more evident in groups infected with 50 and 500 eggs. This study presents an antigenic panel of the excretory-secretory antigen of T. canis and suggests that the 30-35 kDa antigenic fraction is a promising marker of the infection and should be further explored in future studies on experimental toxocariasis.

One Health approach on human seroprevalence of anti-Toxocara antibodies, Toxocara spp. eggs in dogs and sand samples between seashore mainland and island areas of southern Brazil

Toxocariasis, caused by Toxocara spp. nematodes, is among the top 5 neglected parasitic diseases worldwide; however, no comprehensive study to date has serologically compared infections in people and their dogs and environmentally contaminated soil or sand of mainland and island locations. Accordingly, this study aimed to assess the seroprevalence of anti-Toxocara antibodies in traditional human seashore populations, the presence of eggs in dogs' feces and hair, and the presence of eggs in environmental samples from islands compared to the adjacent mainland of southern Brazil. Overall, 212/328 (64.6%) people were positive for Toxocara spp. antibodies, including 125/190 (65.8%) island and 87/138 (63.0%) mainland residents. For dog samples, 12/115 (10.43%) were positive for the presence of Toxocara spp. eggs, all from dogs living in islands, and 22/104 (21.15%) dog hair samples contained eggs of Toxocara spp. Environmental contamination with Toxocara spp. eggs was observed in 50/130 (38.46%) samples from all sampled sites. No significant association was found between risk factors (age, sex, educational level, monthly income, owning dogs or cats, ingestion of treated water, and consumption of raw or uncooked meat) and Toxocara spp. seropositivity. The present study is the first concurrent report on people, their dogs, and environmental contamination of Toxocara spp. The high prevalence we observed in the seashore populations of both in island and mainland areas may be caused by exposure to contaminated sand and climatic factors favoring frequent exposure to Toxocara spp. In conclusion, seashore lifestyle and living conditions of both island and mainland areas may have predisposed higher contact with infected pets and contaminated soil, favoring the high prevalence of toxocariasis.

Toxocariasis as a Rare Parasitic Complication of a Transthoracic Spine Surgery Procedure

Human toxocariasis is a helminthozoonosis caused by the migration of Toxocara species larvae through an organism. The infection in humans is transmitted either by direct ingestion of the eggs of the parasite, or by consuming undercooked meat infested with Toxocara larvae. This parasitosis can be found worldwide, but there are significant differences in seroprevalence in different areas, depending mainly on hot climate conditions and on low social status. However, the literature estimates of seroprevalence are inconsistent. Infected patients commonly present a range of symptoms, e.g., abdominal pain, decreased appetite, restlessness, fever, and coughing. This manuscript presents a case report of a polytraumatic patient who underwent a two-phase spinal procedure for a thoracolumbar fracture. After the second procedure, which was a vertebral body replacement via thoracotomy, the patient developed a pathologic pleural effusion. A microscopic cytology examination of this effusion revealed the presence of Toxocara species larvae. Although the patient presented no specific clinical symptoms, and the serological exams (Enzyme–linked immunosorbent assay (ELISA), Western blot) were negative, the microscopic evaluation enabled a timely diagnosis. The patient was successfully treated with albendazole, with no permanent sequelae of the infection.

Toxocara DNA amplification in serum and tissue samples in BALB/c mice

Toxocariasis is still a neglected parasitic disease worldwide and much about its biology and diagnosis has yet to be understood. The migration of third stage larvae via bloodstream suggests a potential use of molecular tools in diagnosis as well to deepen the knowledge about its migration behaviors. Conventional PCR was applied in serum and tissue samples from BALB/c mice infected with 5 and 500 embryonated eggs. Blood samples were collected at 15, 30, 60, 90 and 120 days post-infection. Organs were excised at 170 days post infection. There was no DNA amplification in serum samples in any group or day post-infection; contrarily, tissue samples showed DNA amplification. These results also support a continuous larval migration after and/or simultaneously with the neurotropic-myotropic phase. Thus, molecular tools might be useful as a differential diagnosis method, but do not replace immunodiagnostics techniques.

Screening of Cystic Echinococcosis and Toxocariasis in Urmia Municipal Workers, Northwest Iran

BACKGROUND

Echinococcus granulosus and Toxocara spp., the causative agents of hydatid cyst and toxocariasis in humans and animals, are zoonotic infections with medical and veterinary significance respectively.

AIM

Herein, we aimed to investigate the seroprevalence of toxocariasis and cystic echinococcosis in Urmia municipal workers (gardeners and sweepers) in 2018 using ELISA assay.

OBJECTIVE

There is no precise report on the seroprevalence of toxocariasis and cystic echinococcosis in Urmia municipal workers using ELISA assay. Therefore, this study found an opportunity to investigate this subject.

METHODS

A total of 220 blood samples were obtained from municipal workers with an average age of 41.31 ± 9.42. Commercial anti-Toxocara canis and hydatid cyst ELISA kits were used to assess the seroprevalence rates.

RESULTS

Approximately, 14.5% and 2.3% of individuals were seropositive for toxocariasis and hydatidosis, respectively. Consuming unboiled milk and/or raw/uncooked meat and rural conditions are risk factors for toxocariasis. Regarding hydatidosis, consuming unwashed vegetables was the only statistically significant risk factor. Toxocara infection (p = 0.01), but not hydatid cyst (p = 0.05), is more prevalent among sweepers than municipal gardeners.

CONCLUSION

Due to the occupational condition of municipal workers, they are exposed to many infectious agents; thus, more researches should be done on these populations.

Toxocara Seroprevalence and Risk Factor Analysis in Four Communities of the Wiwa, an Indigenous Tribe in Colombia

The life of the indigenous Wiwa tribe in northeast Colombia is characterized by lacking access to clean drinking water and sanitary installations. Furthermore, free-roaming domestic animals and use of yucca and/or manioc as a primary food source favor the transmission of soil-transmitted helminths, e.g., Toxocara&nbsp;canis and Toxocara&nbsp;cati, the roundworms of dogs and cats. Infection may result in the clinical picture of toxocarosis, one of the most common zoonotic helminthoses worldwide. To estimate the Toxocara seroprevalence in four different villages of the Wiwa community, serum samples from 483 inhabitants were analyzed for anti-Toxocara-antibodies. Overall, 79.3% (383/483) of analyzed samples were seropositive. Statistically significant differences were observed between the four villages, as well as age groups (adults > adolescents > children), while sex had no effect. The high seropositivity rate demonstrates the risk of zoonotic roundworm infections and potential clinical disease in vulnerable indigenous inhabitants.

Seroprevalence and associated risk factors of toxocariasis among nomads in Boyer-Ahmad County, southwest Iran

BACKGROUND

Human toxocariasis is caused by the larval stage of Toxocara canis and Toxocara cati. This cross-sectional study was conducted to evaluate the seroprevalence and the risk factors associated with Toxocara infection in nomads of Boyer-Ahmad County in the southwest of Iran.

METHODS

A total of 968 blood samples were collected from nomads. A structured questionnaire, containing sociodemographic data, was completed for each participant. Sera were evaluated for anti-Toxocara antibodies, using the T. canis excretory-secretory antigens prepared from the second stage larvae, in an ELISA system.

RESULTS

Among the 968 participants, 220 (22.7%) were males and 748 (77.3%) were females; the mean age was 40.71 y. Anti-Toxocara IgG antibodies were detected in 14 (1.4%) of the 968 nomads. The association between Toxocara infection and gender, age, contact with dogs, residential area and level of education were not statistically significant (p>0.05).

CONCLUSIONS

The findings of the study revealed a low prevalence rate of toxocariasis in nomadic communities in southwest Iran. Geographic location and climatic conditions as well as the lifestyle and sociodemographic features of the participants may contribute to the low prevalence rate of Toxocara infection.

Infectious Causes of Eosinophilic Meningitis in Korean Patients: A Single-Institution Retrospective Chart Review from 2004 to 2018

Eosinophilic meningitis is defined as the presence of more than 10 eosinophils per μl in the cerebrospinal fluid (CSF), or eosinophils accounting for more than 10% of CSF leukocytes in patients with acute meningitis. Parasites are the most common cause of eosinophilic meningitis worldwide, but there is limited research on patients in Korea. Patients diagnosed with eosinophilic meningitis between January 2004 and June 2018 at a tertiary hospital in Seoul, Korea were retrospectively reviewed. The etiology and clinical characteristics of each patient were identified. Of the 22 patients included in the study, 11 (50%) had parasitic causes, of whom 8 (36%) were diagnosed as neurocysticercosis and 3 (14%) as Toxocara meningitis. Four (18%) patients were diagnosed with fungal meningitis, and underlying immunodeficiency was found in 2 of these patients. The etiology of another 4 (18%) patients was suspected to be tuberculosis, which is endemic in Korea. Viral and bacterial meningitis were relatively rare causes of eosinophilic meningitis, accounting for 2 (9%) and 1 (5%) patients, respectively. One patient with neurocysticercosis and 1 patient with fungal meningitis died, and 5 (23%) had neurologic sequelae. Parasite infections, especially neurocysticercosis and toxocariasis, were the most common cause of eosinophilic meningitis in Korean patients. Fungal meningitis, while relatively rare, is often aggressive and must be considered when searching for the cause of eosinophilic meningitis.

Splenic abscess caused by Toxocara spp. in a lung transplant recipient, Marseille, France

Infections represent one of the leading causes of morbidity and mortality in solid organ transplantation (SOT) recipients. Although Toxocara species are prevalent worldwide, toxocariasis is an important neglected human disease that can manifest as visceral or ocular larva migrans, or covert toxocariasis. Herein, we report and discuss the first documented case of a splenic abscess associated with toxocariasis in a 69-year-old lung transplant recipient, in France. This case emphasizes the need to include prevention of toxocariasis in the management of lung transplant patients.

Rational laboratory testing in uveitis: A Bayesian analysis

Uveitis encompasses a heterogeneous group of clinical entities with the common feature of intraocular inflammation. In addition to patient history and examination, a focused set of laboratory investigations is frequently necessary to establish a specific diagnosis. There is limited consensus among uveitis specialists regarding appropriate laboratory evaluation for many distinct patient presentations. The appropriateness of a laboratory test for a given case of uveitis will depend on patient-specific as well as epidemiologic factors. Bayesian analysis is a widely used framework for the interpretation of laboratory testing, but is seldom adhered to in clinical practice. Bayes theorem states that the predictive value of a particular laboratory test depends on the sensitivity and specificity of that test, as well as the prevalence of disease in the population being tested. In this review we will summarize the performance of commonly-utilized laboratory tests for uveitis, as well as the prevalence of uveitic diagnoses in different geographic practice settings. We will propose a logical framework for effective laboratory testing in uveitic disease through rigorous application of Bayesian analysis. Finally, we will demonstrate that while many highly sensitive laboratory tests offer an effective means to rule out associated systemic disease, limited test specificity and low pretest probability often preclude the diagnosis of systemic disease association with any high degree of certainty, even in the face of positive testing.

A new ELISA and western blot technique based on recombinant TES antigen and/or larval antigen for the detection of toxocariasis in humans

Serological antibody detection by enzyme-linked immunosorbent assay (ELISA)- and immunoblot-based methods constitutes the best indicator of human Toxocara infection. Nevertheless, the availability of serological tests, particularly western blots (WB), evaluated for sensitivity and specificity is limited. Therefore, an Anti-Toxocara-ELISA immunoglobulin g (IgG) prototype (Proto-ELISA) and an Anti-Toxocara-Westernblot (IgG) prototype (Proto-WB) were evaluated by testing 541 human sera pre-determined for Toxocara infection by an established in-house Anti-Toxocara-ELISA (IH-ELISA). To evaluate sensitivity and specificity of the newly developed ELISA and WB prototypes, results were compared to IH-ELISA and a commercial WB (Com-WB). Compared to the IH-ELISA, a sensitivity of 93.1% (229/246) and a specificity of 94.6% (279/295) of the Proto-ELISA with a Cohen's κ of 0.88 were obtained. The sensitivity of the Proto-WB was 76.7% (240/313) and specificity was 99.6% (227/228) with a Cohen's κ of 0.73 compared to those of Com-WB. A comparison to the IH-ELISA revealed 91.5% (225/246) sensitivity and 94.6% (279/295) specificity of the Proto-WB with a Cohen's κ of 0.86. Cross-reactivity was observed for some samples positive for Ascaris and Trichinella spp. in the Proto-ELISA, Proto-WB and Com-WB. Overall, the evaluated ELISA and WB prototypes showed high sensitivity and specificity, indicating high reliability of these newly developed tests.

Seroprevalence of Toxocara Infection in Association with Different Risk Factors among Children of 4-12 Years Old Referred to Some Medical Centers in Aras Free Zone, Northwest Iran

Background:

Toxocariosis is a parasitic disease caused by the larval stage of Toxocara species from dog and cat. It has a worldwide distribution with higher prevalence in children. This study aimed to determine seroprevalence of Toxocara infection and its association with some risk factors among children of Aras Free Zone (Jolfa City) in Northwest of Iran.

Methods:

Sera were collected from 514 children aged 4–12 yr old attending to some medical centers in the study area from May 2018 to Feb 2019. Anti-Toxocara IgG antibodies assay was performed using commercial ELISA kit (Nova Tec, Germany). The seropositivity rate was determined and its association with different demographic criteria and risk factors were statistically analyzed.

Results:

The overall seroprevalence was 2.3% (12/514). Risk factors of children’s age group and contact with either pet animals (dog and cat) and/or soil were significantly associated with seropositivity. However, there was not any relationship between Toxocara infection and gender of children, place of residency (urban or rural) and their mothers’ education level.

Conclusion:

Both girls and boys are at risk of Toxocara infection in the study area. Younger age of childhood and contact with sources of infection were important associated factors. More probably, additional criteria are involved in the initiation of infection.

Humoral immune response of pigs infected with Toxocara cati

Toxocara cati is one of the causative agents of human toxocariasis. Serological methods are used for diagnosis in paratenic hosts like humans but the humoral immune response triggered by this parasite is unknown. We characterized the humoral immune response to T. cati excretory-secretory antigens (TES) in pigs as animal model during the acute and chronic stages of infection. ELISA and Western Blot techniques were used to determine antibody response. Pigs were experimentally inoculated with 100,000 infective Toxocara cati eggs. Blood was collected at 7, 14, 21 and 28 days post-inoculation (d.p.i.) to assess the acute stage of infection and 90, 120 and 180 d. p.i. for chronic stage analysis. ELISA showed values higher than the cut-off of specific IgM and IgG at 7 d. p.i. with significant differences at 0 and 7 d. p.i. for IgM and at 14, 21 and 28 d. p.i. for IgG in the acute stage. Higher and stable levels were detected in the chronic stage. Western Blot showed bands from 102 to 38 kDa detected by specific IgM and IgG. More immunogenic bands were identified by specific IgG. In the chronic stage of infection a band near 31 kDa was the only band detected by IgM until 150 d. p.i. Specific IgG recognized bands between 102 and 31 kDa. This study demonstrates how the humoral immune response evolves in the acute and chronic stages of infection and provides evidence on the role of the pig as a paratenic host of T. cati.

An Integrated Study of Toxocara Infection in Honduran Children: Human Seroepidemiology and Environmental Contamination in a Coastal Community

(1) Background: Infections caused by Toxocara canis and T. cati are considered zoonoses of global importance. Reports from North and South America indicate that human infections are widespread in both continents, but epidemiological information from Central America is still lacking. (2) Methodology: In the present cross-sectional multi-year study, we aimed to undertake the first seroepidemiological and environmental study on toxocariasis in Honduras. This included the determination of seroprevalence of anti-Toxocara spp. antibodies in children using a Toxocara spp. purified excretory-secretory antigens enzyme-linked immunosorbent assay (TES-ELISA) and a confirmatory Western blot. As well, through statistical analysis including logistic regression we aimed at identifying relevant biological and epidemiological factors associated with seropositivity. The study also entailed detection of parasites' eggs in the soil samples both through Sheather's concentration method and a nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. (3) Results: The study was undertaken in a coastal community of Honduras in 2 different years, 2015 and 2017. A total of 88 healthy schoolchildren completed the study, with participation of 79% (73/92) and 65% (46/71) of the student body in 2015 and 2017, respectively. Thirty-one children participated in both years (i.e., dual participants). Through both serological tests, seropositivity was confirmed in 88.6% (78/88) of children. Due to the high number of seropositives, logistic regression analysis was not possible for most socio-economic and epidemiological variables. Eosinophilia, on the other hand, was associated with seropositivity, independently of other intestinal helminthic infections. Continued seropositivity was observed in most of the dual participants, while seroconversion was determined in 8 of these children. Microscopic examination of soil samples did not yield any positive results. Through nested PCR-RFLP, 3 of the 50 samples (6%) were positive for Toxocara spp.; two were identified as T. canis and one as T. cati. (4) Conclusions: This work documents for the first time, high levels of human exposure to Toxocara spp. in Honduras. These findings, along with the country's favorable epidemiological conditions for this zoonosis, emphasize the need for more research to determine whether this infection is underreported in the country.

Status of human toxocariasis, a neglected parasitic zoonosis in Iran: a systematic review from past to current

Although human toxocariasis can lead to serious complications including neurological, ocular and visceral complications, there is a lack of comprehensive epidemiological information about the seroprevalence of Toxocara species in humans. In the present study, we analysed and reviewed the overall seroprevalence of human toxocariasis in Iran. The data collection was systematically undertaken on published articles using the PubMed, Google Scholar, ScienceDirect and Scopus databases. A total of 27 studies from the past two decades reporting seroprevalence of human toxocariasis met our eligibility criteria. The pooled proportion of Toxocara infection was estimated as 6.58% (95% confidence interval = 3.98-9.77). A wide variation between different studies was observed (Q statistic = 799.37, df = 26, P < 0.0001, and I² = 96.7%). The seroprevalence rate of toxocariasis in the Iranian population is relatively high; contamination of the environment by eggs from the host as well as from household dogs and cats should be blamed.

Electrochemical detection of Toxocara canis excretory-secretory antigens in children from rural communities in Esmeraldas Province, Ecuador: association between active infection and high eosinophilia

Background

The diagnosis of active Toxocara canis infections in humans is challenging. Larval stages of T. canis do not replicate in human tissues and disease may result from infection with a single T. canis larva. Recently, we developed a nanobody-based electrochemical magnetosensor assay with superior sensitivity to detect T. canis excretory-secretory (TES) antigens. Here, we evaluate the performance of the assay in children from an Ecuadorian birth cohort that followed children to five years of age.

Methods

Samples were selected based on the presence of peripheral blood eosinophilia and relative eosinophil counts. The samples were analyzed by the nanobody-based electrochemical magnetosensor assay, which utilizes a bivalent biotinylated nanobody as capturing agent on the surface of streptavidin pre-coated paramagnetic beads. Detection was performed by a different nanobody chemically labelled with horseradish peroxidase.

Results

Of 87 samples tested, 33 (38%) scored positive for TES antigen recognition by the electrochemical magnetosensor assay. The average concentration of TES antigen in serum was 2.1 ng/ml (SD = 1.1). The positive result in the electrochemical assay was associated with eosinophilia > 19% (P = 0.001). Parasitological data were available for 57 samples. There was no significant association between positivity by the electrochemical assay and the presence of other soil-transmitted helminth infections.

Conclusions

Our nanobody-based electrochemical assay provides highly sensitive quantification of TES antigens in serum and has potential as a valuable tool for the diagnosis of active human toxocariasis.

Global and regional seroprevalence estimates for human toxocariasis: A call for action

Human toxocariasis is a parasitic disease transmitted usually from dogs and/or cats that are infected with Toxocara species, and can be associated with a range of allergic, neurological and/or visual disorders. Recent epidemiological research has estimated that ~1.4 billion people worldwide, particularly in subtropical and tropical regions, are infected with, or exposed to Toxocara species, indicating that human toxocariasis is a neglected tropical disease. Here, we review recent research efforts, consider risk factors, discuss limitations in current seroprevalence estimates, and propose some future research directions towards improved awareness, surveillance, prevention and control of this neglected disease.

Global prevalence of Toxocara infection in cats

Zoonotic parasites, including Toxocara species, of pet and stray cats are of public health importance. Justification for, and the design and implementation of prevention and control of human toxocariasis may benefit from an understanding of the zoonotic potential and prevalence of parasites in this definitive host species. This is the first systematic review and meta-analysis of cross-sectional studies, conducted to estimate the prevalence of Toxocara infection(s) in cats by geographical location, type (rural vs urban and stray vs pet), gender and age. Pooled data were assessed using a random effects-model as well as several meta-regression and stratified analyses conducted. Of 1733 peer-reviewed articles, 143 were included in this review and represented 2,158,069 cats from 51 countries. The global pooled (95% CI) prevalence of Toxocara infection in cats was 17.0% (16.1-17.8%), being highest in African (43.3%, 28.3-58.4%) and lowest in South American (12.6%, 8.2-17.0%) countries. In other WHO regions, prevalence rates of Toxocara were as follows: Eastern Mediterranean (21.6%, 15.1-28.1%), North America (18.3%, 15.4-21.2%), Europe (17.8%, 15.9-19.7%), Western Pacific (17.3%, 14.7-19.9%), and South-East Asia (14.9%, 9.8-20.1%). Prevalence of Toxocara was higher in low-income tropical countries and also in stray (28.6%, 25.1-32.1%) and young (≤12 months of age) (27.7%, 23.4-32.0%) cats than in pet (11.6%, 10.7-12.5%) and older cats (>12 months of age) (23.8%, 14.8-32.7%). This review indicates that ~118-150 million cats worldwide serve as definitive hosts of Toxocara, shedding eggs and thus contributing to the public health risk of human infection. Prevention and control of this zoonosis in cats should receive greater attention by health officials and cat owners, particularly in countries where risk factors and prevalence are highest.

Urticaria and silent parasitism by Ascaridoidea: Component-resolved diagnosis reinforces the significance of this association

Urticaria remains a major problem in terms of aetiology, investigation, and management, and although parasitic diseases are considered potential causes, the absence of a consistent link between parasitic infections and skin allergy symptoms leads to the need for a deeper study of parameters that support this association. The objectives of this study were to analyse a possible relationship between parasitism by Ascarididae (Toxocara canis and Anisakis simplex) and the clinical expression of urticaria and to identify possible parasitic molecular markers for improving the diagnosis of unknown urticaria aetiology. The prevalence of Toxocara and Anisakis infestations was evaluated by measuring the levels of specific IgG (sIgG) and IgE (sIgE) antibodies against crude extracts and isolated components from whole larvae of Anisakis simplex (Ani s 1, Ani s 3 and Ani s 7) and Toxocara canis (TES-120, TES-70, TES-32 and TES-26) using immunologic and molecular diagnostic methods. A cross-sectional study was performed in a group of 400 individuals. The study group consisted of 95 patients diagnosed with urticaria (55 with chronic urticaria and 40 with acute urticaria). A control group consisted of 305 subjects without urticaria (182 diagnosed with respiratory allergy and 123 without allergy). Statistically significant differences were demonstrated in the seroprevalence of specific IgG and IgE antibodies between the urticaria patients and the healthy general population when isolated ascarid antigens were evaluated. The prevalence of IgG antibodies against Ani s 1, IgE antibodies against TES-120 and IgE antibodies against TES-70 were significantly different between the control individuals (healthy general population) and patients with urticaria. Moreover, the urticaria patient group demonstrated a higher seroprevalence of antibodies (sIgE and sIgG) against Anisakis simplex larva whole extract than the control group but just with statistically diferences when sIgE was evaluated. The presence of IgE and/or IgG antibodies against Ani s 3 (tropomyosin) can help to discriminate between patients with and without urticaria. Both ascarids seem to be associated with urticaria, although in our region, Anisakis seems to have greater involvement than Toxocara in this relationship. Molecular diagnostics can be used to associate urticaria with parasite infestations. Tropomyosin and Ani s 1 were the most relevant markers to demonstrate the association between urticaria and the most relevant Ascarididae parasites in our region.

Seroprevalence of Echinococcus spp. and Toxocara spp. in Invasive Non-native American Mink

Invasive non-native species can become reservoirs of zoonotic pathogens and cause their spread during colonization, increasing the risk of zoonoses transmission to both wild hosts and humans. American mink (Neovison vison) are considered an important invasive mammal species responsible for carrying endoparasites. The aim of our study was to evaluate the role of feral American mink as a possible transmission vector of Echinococcus spp. and Toxocara spp. in wildlife. We analysed the frequency of American mink exposure to both parasites, the spatial distribution in Poland, and the variability over time on the basis of specific antibody presence using ELISA and Western blot. Alimentary tract analyses revealed that American mink do not serve as definitive hosts for these parasites. Altogether, 1100 American mink were examined. The average seropositivity for American mink was 14.2% for echinococcosis and 21.7% for toxocarosis; dual-seropositivity was detected in only 6.0%. Seroprevalence of both parasites differed between study sites and significantly increased over time in Toxocara spp. Thus, our study revealed that free-living American mink are exposed to parasites and likely to be involved in the maintenance of both Echinococcus spp. and Toxocara spp. in the wild as paratenic hosts.

Establishment of an Experimental Procedure for Preparing Trial Serum Samples for the Specific Serodiagnosis of Toxocara canis for External Quality Assessment Schemes

Background

External quality assessment (EQA) provides evidence of reliable, accurate, and precise results for customers using the diagnostic test for Toxocara canis. Objective. To establish a procedure for producing standard Toxocara canis serum samples for serodiagnostic testing in EQA.

Methods

The collected serum samples to contain anti-Toxocara canis serum samples for serodiagnostic testing in EQA. F-test and a T-test were applied to evaluate their homogeneity and stability.

Results

Among eleven samples positive by ELISA, ten of them were confirmed via Western blotting by positive reaction with 5 specific Toxocara canis serum samples for serodiagnostic testing in EQA. Toxocara canis serum samples for serodiagnostic testing in EQA. p > 0.05). Samples produced by both methods were stable for 7 days at 30°C (p > 0.05). Samples produced by both methods were stable for 7 days at 30°C (

Conclusion

Specific serodiagnosis samples of anti-Toxocara canis antibodies for EQA could be produced that possessed homogeneity and stability lasting for 3 months and 6 months by the freeze-drying and freezing methods, respectively. At 30°C, the samples produced by both methods were stable for 7 days, suitable for delivery to remote laboratories.Toxocara canis serum samples for serodiagnostic testing in EQA.

Nematode larva migrans caused by Toxocara cati in the North Island brown kiwi (Apteryx mantelli)

Sporadic cases of visceral and neural nematode larva migrans have been diagnosed at necropsy in the endangered New Zealand kiwi (Apteryx spp.), but the causative organisms have not yet been definitively identified. From an initial group of five affected kiwi, PCR was performed on DNA extracted from archival formalin-fixed paraffin-embedded tissue sections in which larval nematodes had been histologically identified. Sequencing of positive results from four out of the five kiwi aligned with sequences from Toxocara cati, a nematode parasite whose definitive host is the domestic cat. PCR was then performed on a second group of 12 kiwi that had histologic inflammatory lesions consistent with larva migrans, but variable larval presence. Repeatable positive PCR results were only achieved in one tissue, in which larval organisms were histologically confirmed. This study supports the use of PCR as an alternative or adjunct to the morphological identification of nematode larvae in formalin-fixed histopathological samples, as well as showing that in investigation of larva migrans, PCR has greatest chance of success from sections where nematode larvae are evident histologically. The identification of Toxocara cati from lesions of larva migrans in kiwi reflects an indirect, parasite-mediated effect of an invasive mammalian species on a native species.

•

Cases of nematode larva migrans have been diagnosed in the New Zealand kiwi.

•

PCR was performed on archival formalin-fixed paraffin-embedded tissue blocks.

•

Results identified Toxocara cati, a parasite of cats, as the causative agent.

•

PCR had greatest success from tissues where larvae were identifiable histologically.

Toxocara seroprevalence in the USA and its impact for individuals and society

Toxocara species are intestinal helminths of dogs and cats, the larval stages of which may infect humans and cause severe neural, ocular and visceral larva migrans disease. Such cases of severe overt disease represent only a small fraction of the of the US population who have been exposed and infected with Toxocara, subsequently developing IgG antibodies to the larvae. The true impact of exposure to Toxocara in this large group of Americans remains uncertain. Toxocara antibody positivity is associated with poverty, but other specific risk factors have been identified, including sex, age, rural residence, region of residence, race and exposure to pets. This seropositive status has also been associated with several childhood diseases, including asthma and epilepsy, increased serum lead levels, and poor neurocognitive function. Three large-scale NHANES studies have provided comprehensive datasets, while several smaller studies have explored specific disease associations. Each seroprevalence study must be interpreted in consideration of the sensitivity and specificity of the individual serological methods employed. This chapter summarizes all historical Toxocara prevalence data from dogs, cats and soil in the United States. It then carefully examines all previous human Toxocara seroprevalence surveys performed in the United States. Data from these surveys is assimilated, compared and discussed to determine the validity of findings and to accurately identify risk factors for Toxocara seropositivity. The validity of associations of exposure to Toxocara larvae and childhood diseases such as asthma and epilepsy and effects neurocognitive function within the American context are also explored.

Toxocara: Protecting pets and improving the lives of people

Toxocara sp. are zoonotic parasitic roundworms that cause infection and morbidity in both developed and developing countries. In humans, infection is thought to be most common in children, particularly those living in poverty, and usually results from consumption of soil contaminated with parasite eggs deposited by dog or cat faeces. Infection in humans results in different clinical manifestations, some more overt like visceral or ocular larva migrans and others more cryptic like neurocognitive delay. Despite its pervasiveness, toxocariasis has become a neglected infection. We review the dynamics of the human-animal interface in the context of this parasite, discuss the challenges in controlling transmission to humans, and cite key areas of research that could enable improved interventions. With political will and proper resource allocation, we propose that effective interventions are possible in the near term.

Serodiagnostic methods for diagnosing larval toxocariasis

Toxocariasis is a human infection primarily caused by larvae of Toxocara canis from dogs, and also by T. cati from cats. Children have a more significant risk of acquiring the infection due to their closer contact with pets, and greater chances of ingesting soil. Diagnosis of toxocariasis is based on clinical, epidemiological, and serological data. Indirect IgG ELISA is a widely used serodiagnostic method for toxocariasis, with native T. canis TES most commonly used as the antigen. Western blots, using the same antigen, can be used to confirm positive ELISA findings to reduce false-positive results. Improvements in Toxocara serodiagnosis include the use of recombinant TES antigens, simpler and more rapid assay formats, and IgG4 subclass detection. Also, incorporation of recombinant T. cati TES protein increases the diagnostic sensitivity. Development of antigen detection tests using polyclonal and monoclonal antibodies, nanobodies, or aptamers can complement the antibody detection assays, and enhance the effectiveness of the serodiagnosis.

Seroepidemiology of human toxocariasis in North Africa

Seroprevalence studies on human toxocariasis help to assess the burden and the morbidity associated with this zoonosis. This review searched the seroprevalence studies and case reports in six North African countries: Algeria, Egypt, Libya, Morocco, Sudan and Tunisia, since 1990. The search also included studies on the environmental factors related to the risk of transmission. Most of the published epidemiological studies were done in Egypt. Cross-sectional and case-control studies in Egypt demonstrated that toxocariasis is a significant zoonosis that could be associated with conditions like bronchial asthma allergies and certain neuropsychiatric disorders. The population at risk of this infection includes all ages, both genders, in contact with dogs, resident in rural areas with poor housing conditions. The publications from Tunisia, Morocco and Algeria are limited to case reports and retrospective analyses of cases, but the disease is probably under-diagnosed in these three countries. There are no published reports on human toxocariasis in Libya and Sudan during the period covered by the review. Animal studies confirm high infection rates of dogs with Toxocara canis in North Africa. There is also evidence of wide-spread contamination of soil and water with Toxocara spp. eggs. Moreover, the use of untreated wastewater for irrigation in parts of North Africa could be a source of contamination of agricultural products with eggs of Toxocara spp. Population-based studies on human toxocariasis are recommended, using standardized diagnostic tests. These surveys should also assess risk factors to guide preventive measures.

Seroprevalence of human toxocarosis in Europe: A review and meta-analysis

Toxocarosis is distributed worldwide and represents the most prevalent zoonotic helminth infection in industrialized countries, thereby posing a substantial risk for public health. Thus, toxocarosis is one of CDC's Neglected Parasitic Infections that has been targeted for public health action. This systematic review and meta-analysis summarizes Toxocara seroprevalence in general populations from Europe, populations suspected of Toxocara infection and defined risk groups. Random-effects meta-analysis of proportions based on 41 publications resulted in an overall seroprevalence of 6.2% (95% CI: 4.7-8.3%) in the general population of Europe. Subgroup analysis according to decades (1970-2010s) revealed a significant increase in seroprevalence, with the highest value (12.4%; 95% CI: 6.5-22.3%) in the 2010s (χ²=17.87, df=4, P=0.001). There were no significant differences between pooled prevalence rates of European sub-regions (χ²=3.01, df=3, P=0.389). Furthermore, meta-analysis of seroprevalence according to age groups, based on data from 22 publications, indicated a significantly higher pooled seroprevalence of 14.9% (95% CI: 8.5-24.8%) in people more than 50 years of age than in younger age cohorts (χ²=8.33, df=2, P=0.016). Occupational groups exposed to contaminated soil and infected animals bear substantial risk for acquiring Toxocara infection. Due to the close link between animal infection and human Toxocara exposure, a "One Health" approach for the prevention of Toxocara infection in both humans and animals is required.

Pathogenesis of cerebral toxocariasis and neurodegenerative diseases

Toxocara canis belongs to one of zoonotic parasites that commonly infects canines worldwide, and its eggs in host faeces may contaminate the food, water, soil and their fur as well as the larvae entrapped in the granuloma can infect paratenic hosts including mice and humans. Survivability of T. canis embryonated eggs under moist, cool conditions may be as long as 2-4 years or more. In paratenic hosts such as mice and humans, T. canis L3 larvae neither moult, grow, nor replicate and will wander through a number of internal organs in humans so as to cause Th2-dominant pathology in various internal organs as leading to neurotoxocariasis (NT), ocular toxocariasis (OT), or visceral larva migrans (VLM). Although the systemic immune response to T. canis has been widely reported, the immune response in the brain has received little attention. Differential cytokine expression and other brain injury-associated biomarkers or neurodegeneration-associated factors have been observed in infected versus uninfected outbred and inbred mice. Preliminary data have also suggested a possible link between significant memory impairment and cytokine production associated with T. canis infection in the hippocampus which has been long recognised as being responsible for learning and memory functions. Notably, it remains an enigma concerning cerebral invasion by T. canis larvae rarely induces a recognisable neurological syndrome or its involvement in neuropathological disorders in humans. Exploration of the relationship between host and parasite in the brain may elucidate the cryptic symptoms of human cerebral toxocariasis, with patients presenting with mental retardation, epilepsy, neurodegeneration and other central nervous system (CNS) disorders.

Toxocara: Seroprevalence in Mexico

In Mexico, toxocariasis, like some other parasitosis in humans, is not a disease of conventional surveillance or immediate notification. Seroprevalence studies are scarce, six dealing with paediatric populations and eight dealing with adults; the reports were only from four states in Mexico. There were 1596 children, and the seroprevalence was 13.8%. In the case of adults, there were 1827 subjects, and seroprevalence was 4.7%. There is a significant positive association between seroprevalence and the paediatric population P<0.0001 (OR, 3.285; 95% CI, 2.541-4.279). It is advisable to perform competitive ELISAs and add another diagnostic test, such as Western blot or the detection of circulating antigens to reduce diagnostic uncertainty. This neglected parasitosis can be confused with retinoblastoma. Therefore, there is a risk of ocular enucleation. It is necessary to sensitise the authorities of the Ministry of Health and decision-makers, to provide economic support for epidemiological surveillance of this zoonotic parasite.

Neurotoxocariasis

Human toxocariasis, caused by larvae of the Toxocara spp., is one of the most prevalent zoonosis with a worldwide distribution. Toxocara larvae can cross the blood-brain barrier, invading the central nervous system (CNS), leading to neurotoxocariasis. The clinical presentation consists of a wide spectrum of neurological manifestations such as meningitis, encephalitis, myelitis and cerebral vasculitis, but asymptomatic CNS infection is common. Despite the high seroprevalence, neurotoxocariasis is thought to be rare, even if in many animal models larvae usually migrate to the brain. Indeed, diagnosis of neurotoxocariasis is rarely considered, and the exact prevalence of CNS involvement is still unknown. Diagnosis of neurotoxocariasis is generally based on the detection of specific antibodies to Toxocara excretory-secretory antigens by ELISA in CSF or serum, and clinical and radiological improvement after anthelmintic therapy, but definitive diagnosis is given by histological confirmation, which is rarely available. Treatment is based on anti-helminthic drugs, commonly albendazole, generally administered with concomitant corticosteroids coverage. At the population level, serological studies suggest an association between Toxocara infections and epilepsy, as well as with other neurodegenerative and psychiatric disorders. Nonetheless the possible role of Toxocara spp. in the pathogenesis of these disorders is still matter of debate.