Toxocara infestations in humans: symptomatic course of toxocarosis correlates significantly with levels of IgE/anti-IgE immune complexes

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.

Infection of Raccoon Dogs (Nyctereutes procyonoides) from Northern Poland with Gastrointestinal Parasites as a Potential Threat to Human Health

The aim of the study was to determinate the prevalence and intensity of infection of raccoon dogs with internal parasites, with a particular emphasis on particular species of helminths known to be dangerous to humans. A total of 96 raccoon dogs were obtained from hunters from September 2018 to October 2021. The digestive tract was taken for examination. The parasitological examination was performed using the dissection methods. The extensity of infection with all internal parasites was 60.3%. The following parasites were found in the tested animals: Echinococcus multilocularis (in 10.42% of animals), Toxocara canis (18.75%), Alaria alata (25.0%), Taenia spp. (19.79%), Uncinaria stenocephala (27.08%), Mesocestoides spp. (54.17%) and Dipylidium caninum (6.25%). The highest mean intensity of infection was demonstrated by A. alata and E. multilocularis then by Mesocestoides spp. This study showed that the raccoon dog from northern Poland is a reservoir host of zoonotic pathogens, such as E. multilocularis, Toxocara canis and Alaria alata. Although the role of the racoon dog as a final host of the life cycle of E. multilocularis is considered of less importance than that of the red fox, this species may increase the risk of echinococcosis in humans, mainly due to its growing population in northern Poland.

Clinical pathology of larval toxocariasis

Human toxocariasis is a worldwide helminth zoonosis caused by roundworms of the genus Toxocara. Toxocariasis is the most common helminth infection in many countries. Disease caused by Toxocara can be classified into five clinical forms: generalised, neurological, ocular, covert, and asymptomatic. The clinical pathology of toxocariasis largely depends on the form of infection, the intensity of the infection, the larvae localisation, and the age of the host. Because histological and molecular examination of toxocariasis is limited by difficulties in obtaining material to analyse, clinical diagnosis is often based on nonspecific tests, such as the detection of eosinophilia and hyperimmunoglobulinemia E (Hyper-IgE). Specific analysis uses an initial ELISA test to detect anti-Toxocara IgG and requires confirmation for all positive results via Western blot. This strategy does not distinguish between actual and recent infections, making the monitoring of disease a challenge for clinicians. Additional research will be required to distinguish active disease from the presence of recent infection.

Diagnosis of ocular toxocariasis by detecting antibodies in the vitreous humor

OBJECTIVES

To demonstrate the production of the local toxocara antibodies in the vitreous of patients with negative serology.

MATERIAL AND METHODS

Retrospective review of the medical records of patients seen in a Tertiary Referral Hospital, and at an Eye Institute, with an ocular diagnosis of toxocariasis who had a negative serology and positive titres in the vitreous.

RESULTS

After reviewing the medical records of 40 patients with a diagnosis of ocular toxocariasis, a total of six cases (15%) were found with a negative serology and a positive vitreous titre for toxocara antibody, both of them performed using an ELISA procedure. The mean age was 18 years, there were no differences observed between males and females. A peripheral granuloma was the most common clinic finding, and all patients underwent vitrectomy either to remove epiretinal membranes or to repair retinal detachments.

CONCLUSION

A negative serology does not rule out a diagnosis of ocular toxocariasis. Vitreous samples may be necessary to confirm a clinical diagnosis.

Clinical course and treatment outcomes of toxocariasis-related eosinophilic disorder

Blood eosinophilia is a common clinical finding. Helminthic infections, including toxocariasis, are a common cause of eosinophilia; however, the clinical course of toxocariasis associated with eosinophilia is not fully understood. Thus, controversies exist regarding treatment indications.To evaluate the clinical features and natural course of various types of eosinophilia, with a particular focus on toxocariasis, we retrospectively reviewed the medical records of 1000 patients with peripheral blood eosinophilia who were referred to the allergy clinic at Asan Medical Center between 2007 and 2012. Clinical parameters and imaging study findings were evaluated. The treatment response to albendazole and resulting changes in eosinophilia and imaging studies were analyzed in patients diagnosed with toxocariasis.Among the 1000 subjects, toxocariasis was the most common cause of eosinophilia (n = 534; 53.4%), followed by allergic disease and adverse drug reactions. The majority of patients with toxocariasis were men, and they were mostly asymptomatic. More than one-third of patients (n = 215; 40.3%) with toxocariasis exhibited organ involvement, particularly hepatic involvement. In most cases of eosinophilia and organ involvement due to toxocariasis, the symptoms normalized regardless of treatment.Most cases of eosinophilia related to toxocariasis displayed a self-remitting course regardless of treatment. With the exception of several clinical situations, including ocular involvement, the clinical need for anti-helminthic therapy in toxocariasis is not that significant.

Evaluation of the prevalence and clinical impact of toxocariasis in patients with eosinophilia of unknown origin

BACKGROUND/AIMS

Eosinophilia has numerous diverse causes, and in many patients, it is not possible to establish the cause of eosinophilia. Recently, toxocariasis was introduced as one cause of eosinophilia. The aims of this study were to evaluate the prevalence of toxocariasis and the clinical impact of albendazole treatment for toxocariasis in patients suspected of eosinophilia of unknown origin.

METHODS

We performed a retrospective chart review. After evaluation of cause of eosinophilia, the patients suspected of eosinophilia of unknown origin performed immunoglobulin G antibody specific assay for the Toxocara canis larval antigen by enzyme-linked immunosorbent assay.

RESULTS

This study evaluated 113 patients, 69 patients (61%) were suspected of eosinophilia of unknown origin. Among these 69 patients, the frequency of T. canis infection was very high (45 patients, 65.2%), and albendazole treatment for 45 eosinophilia with toxocariasis was highly effective for a cure of eosinophilia than no albendazole group regardless of steroid (82.3%, p = 0.007). Furthermore, among the nonsteroid treated small group (19 patients), albendazole treatment for eosinophilia were more effective than no albendazole group, too (83.3% vs. 28.6 %, p = 0.045).

CONCLUSIONS

The prevalence of toxocariasis was high among patients suspected of eosinophilia of unknown origin; therefore, evaluation for T. canis infection is recommended for patients with eosinophilia of unknown origin. Furthermore, for patients suspected of eosinophilia of unknown origin who have positive results for T. canis, albendazole treatment may be considered a valuable treatment option.

Cerebral Toxocariasis: Silent Progression to Neurodegenerative Disorders?

Toxocara canis and T. cati are highly prevalent nematode infections of the intestines of dogs and cats. In paratenic hosts, larvae do not mature in the intestine but instead migrate through the somatic tissues and organs of the body. The presence of these migrating larvae can contribute to pathology. Toxocara larvae can invade the brains of humans, and while case descriptions of cerebral toxocariasis are historically rare, improved diagnosis and greater awareness have contributed to increased detection. Despite this, cerebral or neurological toxocariasis (NT) remains a poorly understood phenomenon. Furthermore, our understanding of cognitive deficits due to toxocariasis in human populations remains particularly deficient. Recent data describe an enhanced expression of biomarkers associated with brain injury, such as GFAP, AβPP, transforming growth factor β1 (TGF-β1), NF-L, S100B, tTG, and p-tau, in mice receiving even low doses of Toxocara ova. Finally, this review outlines a hypothesis to explore the relationship between the presence of T. canis larvae in the brain and the progression of Alzheimer's disease (AD) due to enhanced AD-associated neurodegenerative biomarker expression.

Seropositivity for ascariosis and toxocariosis and cytokine expression among the indigenous people in the Venezuelan Delta region

The present study aimed at measuring seropositivities for infection by Ascaris suum and Toxocara canis using the excretory/secretory (E/S) antigens from Ascaris suum (AES) and Toxocara canis (TES) within an indigenous population. In addition, quantification of cytokine expressions in peripheral blood cells was determined. A total of 50 Warao indigenous were included; of which 43 were adults and seven children. In adults, 44.1% were seropositive for both parasites; whereas children had only seropositivity to one or the other helminth. For ascariosis, the percentage of AES seropositivity in adults and children was high; 23.3% and 57.1%, respectively. While that for toxocariosis, the percentage of TES seropositivity in adults and children was low; 9.3% and 14.3%, respectively. The percentage of seronegativity was comparable for AES and TES antigens in adults (27.9%) and children (28.6%). When positive sera were analyzed by Western blotting technique using AES antigens; three bands of 97.2, 193.6 and 200.2 kDas were mostly recognized. When the TES antigens were used, nine major bands were mostly identified; 47.4, 52.2, 84.9, 98.2, 119.1, 131.3, 175.6, 184.4 and 193.6 kDas. Stool examinations showed that Blastocystis hominis, Hymenolepis nana and Entamoeba coli were the most commonly observed intestinal parasites. Quantification of cytokines IFN-γ, IL-2, IL-6, TGF-β, TNF-α, IL-10 and IL-4 expressions showed that there was only a significant increased expression of IL-4 in indigenous with TES seropositivity (p < 0.002). Ascaris and Toxocara seropositivity was prevalent among Warao indigenous.

Toxocarosis and putative DRESS syndrome in an oncological patient: a case report

Toxocarosis is a parasitic infection caused by Toxocara canis or Toxocara cati. Their definite hosts are the domestic dog and cat, where their adult forms live within the lumen of the small intestine. In humans, infective larvae hatch after ingestion of eggs, but the juvenile stages fail to develop into mature adult worms. Instead, they migrate through the body with the potential to affect virtually every body site. DRESS syndrome (drug reaction with eosinophilia and systemic symptoms) is a serious cutaneous drug reaction, which also involves other organ systems. We report on a 45-year-old man who was admitted with fever up to 40 °C, skin rash and pruritus not responding to amoxicillin/clavulanic acid. Laboratory results showed a slightly elevated white blood cell count, with 62 % eosinophils. History revealed contact to roaming cats. Travel history was unremarkable. Extensive diagnostic workup was performed, and the patient was finally diagnosed with DRESS syndrome, responded to systemic corticosteroid therapy and was discharged. Serology for Toxocara came back positive a few days later. Stool was again sent for microscopy and was found positive for Giardia lamblia, which was treated with a 5-day course of metronidazole. The patient had again developed rash and eosinophilia (62 %). Total immunoglobulin (Ig)E was 1,689 U/l (normal limit: < 100 689 U/l). Follow-up serology showed a marked increase of Toxocara TES ELISA IgG (70 U, normal limit: < 20 U), confirming toxocarosis. Antiparasitic treatment with albendazole 400 mg bid for 5 days was initiated; eosinophilia resolved; and the patient had no further complaints. Although generalized exanthema due to Toxocara has not yet been described in literature, toxocarosis is known to cause a wide spectrum of cutaneous manifestations. Whether our patient had both, a drug reaction with eosinophilia and systemic symptoms and a parasitic infection, or whether a hypersensitivity reaction to Toxocara antigen was mimicking a DRESS syndrome remains unclear.

Toxocara canis: molecular basis of immune recognition and evasion

Toxocara canis has extraordinary abilities to survive for many years in the tissues of diverse vertebrate species, as well as to develop to maturity in the intestinal tract of its definitive canid host. Human disease is caused by larval stages invading musculature, brain and the eye, and immune mechanisms appear to be ineffective at eliminating the infection. Survival of T. canis larvae can be attributed to two molecular strategies evolved by the parasite. Firstly, it releases quantities of 'excretory-secretory' products which include lectins, mucins and enzymes that interact with and modulate host immunity. For example, one lectin (CTL-1) is very similar to mammalian lectins, required for tissue inflammation, suggesting that T. canis may interfere with leucocyte extravasation into infected sites. The second strategy is the elaboration of a specialised mucin-rich surface coat; this is loosely attached to the parasite epicuticle in a fashion that permits rapid escape when host antibodies and cells adhere, resulting in an inflammatory reaction around a newly vacated focus. The mucins have been characterised as bearing multiple glycan side-chains, consisting of a blood-group-like trisaccharide with one or two O-methylation modifications. Both the lectins and these trisaccharides are targeted by host antibodies, with anti-lectin antibodies showing particular diagnostic promise. Antibodies to the mono-methylated trisaccharide appear to be T. canis-specific, as this epitope is not found in the closely related Toxocara cati, but all other antigenic determinants are very similar between the two species. This distinction may be important in designing new and more accurate diagnostic tests. Further tools to control toxocariasis could also arise from understanding the molecular cues and steps involved in larval development. In vitro-cultivated larvae express high levels of four mRNAs that are translationally silenced, as the proteins they encode are not detectable in cultured larvae. However, these appear to be produced once the parasite has entered the mammalian host, as they are recognised by specific antibodies in infected patients. Elucidating the function of these genes, or analysing if micro-RNA translational silencing suppresses production of the proteins, may point towards new drug targets for tissue-phase parasites in humans.

Potential immunological markers for diagnosis and therapeutic assessment of toxocariasis

In human toxocariasis, there are few approaches using immunological markers for diagnosis and therapeutic assessment. An immunoblot (IB) assay using excretory-secretory Toxocara canis antigen was standardized for monitoring IgG, IgE and IgA antibodies in 27 children with toxocariasis (23 visceral, three mixed visceral and ocular, and one ocular form) for 22-116 months after chemotherapy. IB sensitivity was 100% for IgG antibodies to bands of molecular weight 29-38, 48-54, 95-116, 121-162, >205 kDa, 80.8% for IgE to 29-38, 48-54, 95-121, > 205 kDa, and 65.4% for IgA to 29-38, 48-54, 81-93 kDa. Candidates for diagnostic markers should be IgG antibodies to bands of low molecular weight (29-38 and 48-54 kDa). One group of patients presented the same antibody reactivity to all bands throughout the follow-up study; in the other group, antibodies decayed partially or completely to some or all bands, but these changes were not correlated with time after chemotherapy. Candidates for monitoring patients after chemotherapy may be IgG antibodies to > 205 kDa fractions, IgA to 29-38, 48-54, 81-93 kDa and IgE to 95-121 kDa. Further identification of antigen epitopes related to these markers will allow the development of sensitive and specific immunoassays for the diagnosis and therapeutic assessment of toxocariasis.

Regulation and dysregulation of immunoglobulin E: a molecular and clinical perspective

BACKGROUND

Altered levels of Immunoglobulin E (IgE) represent a dysregulation of IgE synthesis and may be seen in a variety of immunological disorders. The object of this review is to summarize the historical and molecular aspects of IgE synthesis and the disorders associated with dysregulation of IgE production.

METHODS

Articles published in Medline/PubMed were searched with the keyword Immunoglobulin E and specific terms such as class switch recombination, deficiency and/or specific disease conditions (atopy, neoplasia, renal disease, myeloma, etc.). The selected papers included reviews, case reports, retrospective reviews and molecular mechanisms. Studies involving both sexes and all ages were included in the analysis.

RESULTS

Both very low and elevated levels of IgE may be seen in clinical practice. Major advancements have been made in our understanding of the molecular basis of IgE class switching including roles for T cells, cytokines and T regulatory (or Treg) cells in this process. Dysregulation of this process may result in either elevated IgE levels or IgE deficiency.

CONCLUSION

Evaluation of a patient with elevated IgE must involve a detailed differential diagnosis and consideration of various immunological and non-immunological disorders. The use of appropriate tests will allow the correct diagnosis to be made. This can often assist in the development of tailored treatments.

Recurrent cerebral larva migrans: A case report and review of literature

Cerebral larva migrans (CLM) is an uncommon and rarely diagnosed entity. We report here a histopathologically proven case of CLM in a 13 year-old girl, who presented with bilateral focal seizures, right hemiparesis, and lapsed into altered sensorium prior to admission. Her CT scan was suggestive of a granulomatous lesion which eventually turned out to be CLM (toxocariasis). Interestingly, the lesion recurred after excision, with a confusing clinical picture. Following the second surgery, the pathology was reconfirmed and cure was provided for the disease. There has been no further intracranial recurrence during the past ten years although she developed cutaneous lesions.

Application of Toxocara canis excretory-secretory antigens and IgG subclass antibodies (IgG1-4) in serodiagnostic assays of human toxocariasis

A major problem in the serodiagnosis of human toxocariasis in tropical countries is cross-reaction with antibodies to other helminthic diseases and a lack of sensitivity. The majority of tests currently available use total IgG and, in this study, the use of peroxidase-conjugated anti-human IgG subclass antibodies (IgG1-4) was compared with total IgG for the diagnosis of human toxocariasis by using Toxocara excretory-secretory (TES) antigens in an enzyme-linked immunosorbent assay (ELISA) format. All four IgG subclass antibodies gave approximately 10-fold increases in optical density (OD) values for 50 toxocariasis patients compared to 29 healthy normals; this was significantly greater than the approximate doubling of OD values seen in the total IgG-ELISA format. IgG2 gave by far the greatest sensitivity (values: IgG, 50%; IgG1, 60%; IgG2, 98%; IgG3, 78%; IgG4, 64%). Significant cross-reactivity using all IgG subclasses in the TES ELISA was seen with 141 serum samples from patients with 10 other helminthic infections. However, IgG3 gave the best specificity (values: IgG, 73%; IgG1, 76%; IgG2, 71%; IgG3, 81%; IgG4, 71%). Thus, of the IgG subclass antibodies, IgG2 appeared best and employing this subclass can improve the serodiagnosis of human toxocariasis since it recognises carbohydrate epitopes of TES antigens.

The effect of an indirect anthelmintic treatment on parasites and breeding success of free-living pheasantsPhasianus colchicus

In Great Britain free-living common pheasantsPhasianus colchicusare often managed at high densities owing to their popularity as a quarry species. They are prone to infection by a range of parasite species includingHeterakis gallinarum,Capillariaspp. andSyngamus trachea. In 1995 the efficacy of an indirect anthelmintic technique for controlling parasitic worm burdens of pheasants was determined in a pilot study on a shooting estate in the south of England. Between 2000 and 2003 a large-scale field experiment was conducted on nine estates in eastern England to determine the effect of the technique on parasite burden and pheasant breeding success. In the absence of anthelmintic treatment worm burdens increased rapidly through March and April, whereas birds given anthelmintic-treated grain had lower worm burdens during the same period. The breeding success of pheasants was significantly higher on plots provided with anthelmintic treatment, although no long-term increases in population densities were observed. The burdens of the most common parasiteH. gallinarumwere significantly lower in pheasants from treatment plots six weeks after the anthelmintic treatment had ceased, but spring treatment did not influence parasite burden in the following winter.

Eosinophil cationic protein, specific IgE and IgG4 in human toxocariasis

Among 67 French patients presenting a toxocaral infection, various demographic, environmental, clinical and laboratory parameters (blood eosinophil count, eosinophil cationic protein (ECP), serum total IgE, specific IgE against common inhalant allergens, specific IgE and IgG4 againstToxocaraexcretory-secretory antigens) were investigated. Correlation studies and logistic regression analyses were conducted, testing elevated levels of ECP, specific anti-ToxocaraIgE or IgG4 as outcome variables An elevated ECP level was significantly associated with both cough and rhinitis, a high level of specific anti-ToxocaraIgE with itchy rashes and possible atopic status, and an increase of specific anti-ToxocaraIgG4 with rural residence.

A serological follow-up of toxocariasis patients after chemotherapy based on the detection of IgG, IgA, and IgE antibodies by enzyme-linked immunosorbent assay

A serological follow-up study was carried out on 27 children (1-12 years old) with visceral and/or ocular toxocariasis, after treatment with thiabendazole. A total of 159 serum samples were collected in a period ranging from 22-116 months. Enzyme-linked immunosorbent assays (IgG, IgA, and IgE ELISA) were standardized, using excretory-secretory antigens obtained from the second-stage larvae of a Toxocara canis culture. The sensitivity found for the IgG, IgA, and IgE ELISA, as determined in visceral toxocariasis patients, was 100%, 47.8%, and 78.3%, respectively. Approximately 84% of the patients presented single or multiple parasitosis, as diagnosed by stool examination, yet such variables did not appear to affect the anti-Toxocara immune response. Titers of specific IgE antibody showed a significant decrease during the first year after treatment, followed by a decrease in the IgA titers in the second year, and in the IgG titers from the fourth year onwards. Sera from all patients presented high avidity IgG antibodies, indicating that they were in the chronic phase of the disease. Moreover, 1 year after treatment, the level of leukocytes, eosinophils, and anti-A isohemagglutinin in patients decreased significantly. The present data suggest that IgE antibodies plus eosinophil counts are helpful parameters for patient follow-up after chemotherapy.

Toxocara canis: effect of inoculum size on pulmonary pathology and cytokine expression in BALB/c mice

Infection of mice with Toxocara canis results in pulmonary inflammation and the induction of a Th2 type of immune response. The aim of this study was to determine whether the effect of infection with this nematode depends on the inoculum size. Results indicate that mice infected with either a high or a low inoculum size showed, in a dose-dependent manner, pulmonary inflammation with eosinophil infiltration, increased levels of total IgE, and Toxocara-specific IgG1 that persisted up to 60 days p.i. Relative quantification of cytokine expression in lungs of mice infected with different doses showed proportional increased expression of the IL-4, IL-5, and IL-10 transcripts, whereas the expression of the IFN-gamma transcript was not different from that of uninfected controls. These results indicate that infection of BALB/c mice with T. canis results in chronic pulmonary inflammation and a dominant Th2 type of immune response, independent of the inoculum size.

The prevalence and diagnostic value of toxocariasis in unknown eosinophilia

Toxocariasis is one of the causes of eosinophilia in peripheral blood and provokes eosinophilic infiltration in internal organs. Extended studies on the prevalence and clinical characteristics of toxocariasis have been rare. The aim of this study is to evaluate the prevalence of toxocariasis in unknown eosinophilia and to analyze the efficacy of toxocara enzyme-linked immunosorbent assay (ELISA). We evaluated patients presenting with peripheral blood eosinophilia (>500 cells/microl or > or =10% of white blood cell count). After checking drug histories and the presence of allergic diseases and parasitic infections, specific serum IgG antibody to Toxocara canis larval antigen was measured by ELISA. Liver and lung involvement was also evaluated. One-hundred and three patients were evaluated, and the mean age was 50.9 years old. Seventy patients (68.0%) were diagnosed as having toxocariasis. The patients who had a history of raw liver eating had a higher incidence, and the patients with liver involvement had higher serum eosinophil cationic protein values. The eosinophil count was normalized in 7 of 16 treated patients and in 25 of 54 untreated patients. The mean improvement duration was 12 months. We concluded that the prevalence of toxocariasis was high in patients with unknown eosinophilia, and the toxocara ELISA was essential for evaluation of the causes of unknown eosinophilia.

[Systemic vasculitis during parasitosis]

A RARE EVENTUALITY: Although parasite infections are frequent, observations of vasculitis related to parasitosis are, however, very rare. REGARDING THE MECHANISM: The simultaneous occurrence of a parasitosis and vasculitis may be the consequence of either the direct implication of a parasite observed in the histological lesions in the onset of alteration in the vascular wall, or of immunopathological phenomena occuring during the anti-parasite immune response, or a fortuitous association. THE HUMAN PARASITOSIS IMPLIED: In most cases, vasculitis associated with parasitosis is an isolated event with varied clinical aspects. Such cases have been reported in toxoplasmosis, trichinosis, strongyliasis, ascaridiosis, sarcocystosis, amibiasis, leishmaniosis and toxocarosis.

Association of autoantibodies against small nuclear ribonucleoproteins (snRNPs) with symptomatic Toxocara canis infestation

Several studies have demonstrated the occurrence of autoantibodies in the course of infestations with helminth parasites and a number of target proteins have been identified. Sera from patients suffering from toxocarosis, a disease caused by the parasitic roundworm Toxocara canis, and from healthy individuals were tested for autoantibodies by immunofluorescence and immunoblot assays using HEp-2 cells as antigen. A considerable proportion of the sera from patients with toxocarosis-associated symptoms were autoantibody-positive, with a speckled staining pattern in the immunofluorescence test (62%) and with anti-snRNP reactivity in the immunoblot assay (98%). In contrast, significantly fewer sera from asymptomatic individuals scored positive in these assays (18% in the immunofluorescence test, P < 0.005; 24% in the immunoblot, P < 0.005). Although the causative link between Toxocara infestation and the occurrence of autoantibodies is still unclear, our results show that increased amounts of autoantibodies are associated with clinical symptoms of inflammation. Thus a serum test for autoantibodies in toxocarosis patients might be a valuable gatekeeper assay for the decision for or against anti-inflammatory treatment.

Toxocariasis: clinical aspects, epidemiology, medical ecology, and molecular aspects

Toxocariasis is caused by a series of related nematode species (ascarids) that routinely infect dogs and cats throughout the world. The eggs from these ascarids are common environmental contaminants of human habitation, due largely to the fact that many kinds of dogs and cats serve as pets, while countless others run wild throughout the streets of most urban centers. The eggs, present in dog and cat feces, become infectious within weeks after they are deposited in the local environment (e.g., sandboxes, city parks, and public beaches, etc.). Humans, particularly children, frequently ingest these eggs by accident and become infected. Infection in humans, in contrast to their definitive hosts, remains occult, often resulting in disease caused by the migrating larval stages. Visceral larva migrans (VLM) and ocular larva migrans (OLM) are two clinical manifestations that result in definable syndromes and present as serious health problems wherever they occur. Diagnosis and treatment of VLM and OLM are difficult. These issues are summarized in this review, with emphasis on the ecology of transmission and control of spread to both humans and animals through public health initiatives employing treatment of pets and environmental intervention strategies that limit the areas that dogs and cats are allowed within the confines of urban centers.

Toxocariasis in humans: clinical expression and treatment dilemma

A new scheme of clarifying clinical forms of toxocariasis is proposed to include: (i) systemic forms: classical VLM and incomplete VLM; (ii) compartmentalized forms: ocular and neurological toxocariasis; (iii) covert toxocariasis; and (iv) asymptomatic toxocariasis. The following markers are helpful in defining clinical forms namely, patient characteristics and history, clinical symptoms and signs, positive serology, eosinophilia and increased levels of IgE. Amongst the available drugs albendazole is the most commonly used, although other benzimidazole compounds have a similar efficacy. The recommended dose of albendazole is 15 mg kg(-1) body weight daily for 5 days and in some cases with VLM syndrome the treatment needs to be repeated. An evaluation of treatment efficacy can be made by observing a rise in eosinophilia within a week followed by any improvement in clinical symptoms and signs, lower eosinophilia and serological tests taken over a period of at least 4 weeks. In addition to clinical rationales for the specific treatment of VLM and OLM, preventive treatment needs to be considered bearing in mind the increasing risk of larvae localizing in the brain during the course of an infection. To reduce migration of Toxocara larvae a single course of albendazole is suggested in cases where eosinophilia and serology are at least moderately positive.

Helminthic infestations in the Tyrol, Austria

At the federal public health laboratory, Innsbruck, 142 426 samples were examined for intestinal helminthosis from 1990 until 2000. Enterobius vermicularis accounted for half (49.7%) of the cases diagnosed, followed by Taenia saginata (28.3%), Ascaris lumbricoides (12.8%), and Trichuris trichiura (3.9%). Of all specimens tested for helminths, 26% had been positive in 1945, and 0.98% in 1985. The proportion of positive findings with respect to the total number of specimens tested was 0.24% in the time span 1990-2000. It appears to us that these numbers fairly reflect the real prevalence of helminthosis in Austria.

Severe hepatic involvement in visceral larva migrans

Because of its anatomical position, the liver may be involved in many protozoan and helminthic gastrointestinal infections. Visceral larva migrans caused by Toxocara canis is rarely taken into account in adult patients with cholestatic syndrome, especially when liver disease is not associated with hypereosinophilic reaction. We report on a 74-year-old immunocompetent woman who presented with fever, bronchospasm, erythema nodosum, weight loss and progressive jaundice. A liver biopsy showed caseating granulomatous hepatitis with secondary portal fibrosis and paucity of interlobular bile ducts. A step-by-step search for aetiological factors led us to a diagnosis of toxocariasis (positive enzyme-linked immunosorbent assay IgG test). An excellent clinical response to combined treatment with steroid and diethylcarbamazine, and a reduction in the antibody level against T. canis supported the diagnosis. Computed tomography and laparoscopy demonstrated multiple small mass lesions and fibrous perihepatitis. This report shows that visceral larva migrans may be a cause of prostrating chronic liver disease and should be suspected in every febrile patient with cryptogenic cholestatic hepatitis.

Allogeneic bone marrow transplantation-mediated transfer of specific immunity against Toxocara canis associated with excessive IgE

A girl with myelodysplastic syndrome (RAEB-T) received HLA-identical bone marrow from her younger brother after myeloablative treatment with busulfan and cyclophosphamide. After bone marrow transplantation, fever, exanthema, pruritus, and a pulmonary infiltrate were treated symptomatically. Bacterial cultures remained negative. Leukocyte engraftment began on day 10, and all blood cell populations proved to be of donor origin on FISH analysis. Increasing IgE levels (21 000 U/ml) on day 14 after BMT, positive RAST, specific IgG-antibodies, and missing Toxocara (T.) canis antigens in the recipient indicated donor-derived seroconversion. Before BMT, the recipient had been negative for T. canis in routine parasitological screening, and the donor proved to be positive for T. canis antibody by ELISA. This report suggests that the transfer of IgE immunity in the absence of detectable antigens may be responsible for IgE-mediated symptoms consistent with toxocara infection and confirms the need for parasite screening in donor medical examinations.

Treatment of ocular toxocariasis with albendazole

The purpose of this study was to evaluate the efficacy of combined albendazole and steroid treatment for uveitis caused by Toxocara canis in immunocompetent patients. Five patients (7 eyes) with ocular larva migrans syndrome (OLM) were used in this study. Toxocariasis was suspected based on clinical manifestations and confirmed by anti-toxocara IgG and Western blot analysis. Systemic albendazole (adults: 800 mg b.i.d.; children: 400 mg b.i.d.) was given in conjunction with steroids. Visual acuity before and after therapy, inflammatory response, side effects and toxicity were evaluated. Treatment resulted in an improved visual acuity in all patients. Mean initial Snellen visual acuity was 20/40, and mean final acuity was 20/20. There were no recurrences of uveitis throughout the observation period (average: 13.8 months; range: 3 days to 24 months). These findings suggest that albendazole, in combination with systemic steroids, is a useful regimen to treat ocular larva migrans syndrome.

Toxocarosis as zoonosis. A review of literature and the prevalence of Toxocara canis antibodies in 511 serum samples

A total of 511 serum samples from children aged between 6 months to 15 years old, with different clinical signs-living in the region of Northern Greece - were tested by ELISA (enzyme links immunosorbent assay) technique, for the detection of specific IgG and IgM antibodies against T. canis antigen. The reason IgM was detected was because IgM levels are elevated in the acute phase of toxocara infection, in spite of their notorious non-specificity. In this seroepidemiologic survey of children, a remarkably high percentage (12.5&#x0025;) reacted positively to this method. Sixteen (3.1&#x0025;) out of 511 sera showed IgG antibodies, 43 (8.4&#x0025;) showed IgM, while 5 (1&#x0025;) showed both IgG and IgM antibodies against T. canis E/S (excretory - secretory) antigen. Females were significantly more infected than males. Seropositivity rate was highest in children over the age of 10.