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PubMed2000

Comparison of the sensitive screening kit with two ELISA sets for detection of anti-Toxocara antibodies.

Three serological tests (ELISA NOVUM, ELISA PU and ToxocaraCHEK) were compared using excretory-secretory (ES) antigen of second stage larvae of Toxocara canis on two sets of sera from patients aged 1-15 years, living in town and in the country, suspected of having larval toxocarosis. Of 60 serum samples examined for the presence of anti-Toxocara IgM and IgG antibodies 35 (58.3%) were positive with ELISA NOVUM, 30 (50.0%) with ELISA PU and 37 (61.6%) with ToxocaraCHEK. A significantly higher seropositivity with all the tests was detected in group of patients from the village (test chi2, p < 0.005) when compared with patients from the town. The highest sensitivity (100%) was detected for a rapid qualitative ToxocaraCHEK. Compared with this screening test, both ELISA sets showed higher specificity but a lower sensitivity. Consistent findings (+;-) with ELISA NOVUM and ELISA PU were 88.3%; ELISA NOVUM and ToxocaraCHEK 96.7% and ELISA PU and ToxocaraCHEK 86.7%. This comparison indicates the suitability of ToxocaraCHEK set for screening for its simplicity and rapidity in detecting anti-Toxocara antibodies.

Adolescent↗
PubMed1984

Toxocara canis infection of the eye. Correlation of clinical observations with developing pathology in the primate model.

A primate model for the study of Toxocara canis infection was created by intravitreal, periocular, systemic, and intracarotid injection of viable larvae in cynomolgus monkeys. The results were as follows: (1) Intravitreal larvae caused retinal hemorrhages, perivasculitis, mild vitritis, and retinal nodules. (2) Apparently viable larvae without inflammatory reaction were found in the vitreous, retina, and optic nerves up to nine months after intravitreal inoculation. (3) Other larvae were surrounded by an acute inflammatory granuloma or a chronic fibrotic granuloma, but they did not appear to be necrotic. (4) Toxocara canis larvae apparently had the ability to move through ocular tissue, to leave the site of tissue reaction, and to exit via the optic nerve. Viable larvae were found in the retina up to 15 months after inoculation. (5) Culture fluid containing Toxocara proteins stimulated a severe retinal vasculitis. Dead larvae caused little reaction. (6) Positive aqueous and vitreous enzyme-linked immunosorbent assay titers were found in the most severely inflamed eyes, which often harbored live larvae.

Animals↗
PubMedDate not supplied

Toxocara antibodies in patients with visceral or ocular disorder in Slovenia.

The incidence of Toxocara antibodies was determined in 319 sera from patients suspected of having Toxocara infection. Serological responses were compared with clinical manifestations and age of the patients. A seropositive reaction was found in 24% of the patients. Highly positive results (OD 0.510-1.000 and OD > 1.000) by ELISA were obtained significantly more frequently in younger patients than in older ones (p < 0.005). The percentage of seropositive patients with visceral disorder was found to decrease with age, whereas the proportion of seropositive patients with ocular disorder increased with age. Serologically confirmed Toxocara infection in Slovenia alerted us to the fact that this health issue should be given due attention in the future.

Adolescent↗
PubMed2005

Toxocara-infestations in Austria: a study on the risk of infection of farmers, slaughterhouse staff, hunters and veterinarians.

A total of 585 persons from several occupational groups (farmers, slaughterhouse staff, hunters, veterinarians) exposed to Toxocara infestations and 50 persons of a control group were tested for the presence of specific antibodies to the Toxocara canis antigen using an enzyme-linked immunosorbent assay and a western blot. Farmers showed the highest seroprevalence (44%), followed by veterinarians (27%), slaughterhouse staff (25%) and hunters (17%), whereas only 2% of the individuals of the control group were seropositive. Thus, the risk to Toxocara infestation is 39, 18, 16 and 9 times higher for farmers, veterinarians, slaughterhouse staff (some workers were part-time farmers) and for hunters, respectively, when compared to the control group. The main source of infection in rural areas seems to be (roaming) farm cats and dogs that have not been dewormed. The results are discussed with a view to potential risk factors and preventive measures, in terms of veterinary and human medicine.

Abattoirs↗
PubMedDate not supplied

Following the migration of a Toxocara larva in the retina by optical coherence tomography and fluorescein angiography.

BACKGROUND: The Toxocara larva is known to migrate across the retina, but the layer in which it migrates and its effect on the retina has been unknown. CASE: An ocular Toxocara infection was diagnosed by an immunological test on a vitreous sample from a patient with a retinal lesion that had migrated. Optical coherence tomography (OCT) and fluorescein angiography (FA) were used in this investigation. OBSERVATIONS: Many small lesions were first detected in the peripheral retina, and vitrectomy was performed because of vitreous haze. Two peripapillary lesions were found during the vitrectomy. OCT of one lesion demonstrated a highly reflective mass located in the nerve fiber layer, and FA showed dye leakage from the lesion as well as hyperfluorescence of the disc. Three weeks later, another lesion was found in the macular area, and OCT and FA findings were the same as for the first lesions. Fluorescein leakage was also observed along the presumed path of the migrating larva. CONCLUSIONS: The movement of the lesion from the peripapillary area to the macular area suggested that a Toxocara larva had migrated across the retina. OCT images indicated that the larva moved in the nerve fiber layer, and FA showed that it caused severe inflammation along its pathway.

Animals↗
PubMed1992

Toxocara canis: monoclonal antibodies to carbohydrate epitopes of secreted (TES) antigens localize to different secretion-related structures in infective larvae.

The major secreted glycoproteins of Toxocara canis larvae appear to be derived from two specialized organs within the nematode organism. Using immunogold electron microscopy, we have analyzed the binding patterns of a panel of monoclonal antibodies (Tcn-1 to Tcn-8) reactive with Toxocara excretory-secretory (TES) antigens. We find, first, that the esophageal gland and lumen are strongly reactive with monoclonals Tcn-4, Tcn-5, and Tcn-8, and because the posterior portion of the gut is closed, we hypothesize that products of this gland are released through the oral aperture. Second, a distinct anti-TES antibody (Tcn-2) localizes solely to the midbody secretory column, which opens onto the cuticle at a secretory pore. Thus, the secretory apparatus is probably functional in this stage of parasite as an important source of TES products. Only one monoclonal, Tcn-7, can bind to both esophageal and secretory structures. In addition, another antibody, Tcn-3, binds both to the epicuticle and to a TES antigen, but our data do not directly determine whether antigens located in the cuticle are subsequently released. Thus there are at least two, and possibly three, independent sources of TES antigens within Toxocara larvae.

Animals↗
PubMed1988

Environmental contamination by eggs of Toxocara species.

A study was conducted to determine the level of contamination with Toxocara spp. eggs in parks and playgrounds in several central Illinois communities. A total of 135 composite 50-g soil samples were collected from 23 parks and public places in three cities in central Illinois. Of these soil samples, 22 (16.3%) contained from one to thirteen Toxocara spp. eggs. A total of 40 fecal samples were collected from the same parks. Toxocara spp. eggs were found in two (5%) of the samples.

Animals↗
PubMed2006

Toxocara seroprevalence in adults with bronchial asthma.

The aim of this study was to determine the seroprevalence of toxocariasis in adult asthmatics and to assess its relationship with risk factors. A total of 124 asthmatic and 60 control group subjects were included in the study. Of the asthmatic patients, 61 (49.2%) were atopic and 63 non-atopic (50.8%). The anti-Toxocara IgG (Toxocara IgG CELISA Cellabs, Australia) positivity rate for all asthmatic cases was 9.7%. There was no significant difference between the asthmatic cases and the control group regarding anti-Toxocara IgG positivity (P>0.05). When risk factors were analyzed, there was a statistically significant difference between the control group subjects and patients with non-atopic asthma and also between the atopic asthmatic patients and the patients with non-atopic asthma regarding pets being under veterinary control (P<0.05). The percentages of those who had their pets defecate indoors were 0, 15 and 8.6%, respectively, for the control subjects, patients with non-atopic asthma and those with atopic asthma. There was a statistically significant difference when the control group subjects were compared to the patients with atopic asthma (P<0.05).

Adult↗
PubMed2006

Comparative effects of milbemycin oxime-based and febantel-pyrantel embonate-based anthelmintic tablets on Toxocara canis egg shedding in naturally infected pups.

The effect of two treatment programmes on egg shedding in dogs naturally infected with Toxocara canis, one based on a milbemycin oxime-praziquantel-lufenuron combination (SENTINEL) Spectrum; Group 1) and the other based on a febantel-pyrantel embonate-praziquantel combination (DRONTAL) Plus; Group 2), was compared in a study involving 104 suckling pups from three different kennels. The animals in Group 1 were treated at a minimum milbemycin oxime dose of 0.5 mg/kg bw starting at 2 weeks of age and subsequently every 4 weeks until reaching 26 weeks of age. The animals in Group 2 were treated every 2 weeks from week 2 until week 12 of age and then once at week 26 at a minimum febantel and pyrantel embonate dose of 15.0 and 14.4 mg/kg bw, respectively. Toxocara egg counts were determined fortnightly starting at 2 weeks of age and continuing until 26 weeks of age for every pup. Any adverse drug event was recorded during the trial. Both treatment programmes significantly reduced the zoonotic Toxocara egg shedding and were well tolerated by the pups. The pups in Group 1 showed lower average faecal egg counts and were found more frequently shedding no eggs than the pups in Group 2.

Animals↗
PubMed1998

Tests on the centrifugal flotation technique and its use in estimating the prevalence of Toxocara in soil samples from urban and suburban areas of Malaysia.

The influence of soil texture (silt, sand and laterite) and flotation solutions (saturated NaCl, sucrose, NaNO3, and ZnSO4) upon the recovery of Toxocara ova from seeded soil samples with the centrifugal flotation technique was investigated. Soil samples of different texture were artificially seeded with Toxocara spp. ova and subjected to a centrifugal flotation technique which used various flotation solutions. The results showed significant (P < 0.001) interactions between the soil types and the flotation solutions. The highest percentage of ova recovery was obtained with silty soil (34.9-100.8%) with saturated NaCl as the flotation solution (45.3-100.8%). A combination of washing of soil samples with 0.1% Tween 80, and flotation using saturated NaCl and a 30 min coverslip recovery period was used to study the prevalence of contamination of soil samples. Forty-six soil samples were collected from up to 24 public parks/playgrounds in urban areas of Petaling Jaya and suburban areas of Serdang. The prevalence of Toxocara species in the urban and suburban areas was 54.5% and 45.8% respectively.

Animals↗
PubMed2006

Influence of Toxocara canis infection during pregnancy on offspring resistance towards re-infection.

The impact of Toxocara canis infection of Balb/c mice mothers on the future immune response of their offspring towards reinfection with the same parasite was studied. Two groups of offspring, the first originating from the mothers infected with a single dose of 1000 Toxocara canis eggs and the second from non-infected mothers, were both challenged with 500 T. canis eggs per animal at 6 weeks of age. The proportions of spleen CD4+ and CD8+ T lymphocytes, the level of serum cytokines IFN-gamma and IL-5, eosinophilia in peripheral blood, the production of specific antibodies and the number of migrating larvae were monitored. In both groups of offspring, the challenge infection resulted in an increase in CD4+ T-cell subtype in comparison with the non-infected healthy control, although after an initial decline a subsequent increase in CD8+ was observed. The immunoregulation index (CD4+/CD8+) was lower in the group of mice originating from infected mothers throughout the whole experiment compared to the offspring of non-infected mothers as well as in healthy control mice of the same age. In the offspring of infected mothers mainly, a reduced production of IFN-gamma and of IL-5, suppressed eosinophilia and a higher level of protective antibodies was detected, compared to the control second group, in which the INF-gamma concentration significantly increased after day 42 p.i. In the first group of offspring before challenge, 12.7 +/- 2.5 larvae in the brains and 32 +/- 2.1 larvae in the muscles transmitted from the infected mothers were detected. There was a significant reduction in larval recovery from brain on days 42 and 49 p.i. (56.7 and 56.8%, respectively), while from muscles in the same time there was a reduction of 46.7 and 39%, respectively, compared to the offspring of non-infected mothers. These results indicate a significant protective memory of immune mechanisms against T. canis induced in offspring of Toxocara-infected mother mice.

Animals↗
PubMed2001

Eosinophil cationic protein as a possible marker of active human Toxocara infection.

BACKGROUND: Human toxocariasis is a common, worldwide helminthozoonosis that may elicit syndromes including various allergy symptoms. The diagnosis relies upon specific serology. However, this parasitosis is often self-limiting, and many subjects have residual antibodies, thus making differential diagnosis quite difficult when blood eosinophilia, a commonly accepted criterion of active helminthiasis due to tissue-dwelling parasites, is lacking. METHODS AND RESULTS: We present a patient with chronic irritant cough displaying negative allergologic screening, normal blood eosinophilia, but positive toxocariasis immunodiagnosis. Therefore, this case presented the fortuitous association of an unexplained allergic picture with residual anti-Toxocara antibodies. In an attempt to distinguish between active and past toxocaral infection, the subject's level of eosinophil cationic protein (ECP) was assessed and then compared to those of four control groups, namely, healthy volunteers, subjects presenting anti-Toxocara residual antibodies, patients with various helminthiases, and patients with active toxocaral disease. Since the patient's ECP level was found to be sharply elevated, we hypothesized that viable Toxocara larvae were still present in the tissues, and the patient was given anthelmintic therapy. At the control checkup, the cough had waned and the ECP level had decreased to below the mean value observed in both healthy subjects and in subjects with past toxocaral infections. CONCLUSIONS: These data suggest, first, that patients presenting unexplained allergic syndromes should be checked for helminthiases, even if blood eosinophilia is lacking, and, second, in such subjects displaying positive toxocariasis immunodiagnosis, ECP assessment would be a useful marker to distinguish between active and past toxocaral disease.

Animals↗
PubMed1998

Eosinophilia, IgE production, and cytokine production by lung T cells in surface CD4-deficient mutant mice infected with Toxocara canis.

Mutant mice deficient in CD4+ T cells and their normal and heterozygous littermates were infected with Toxocara canis, and compared for eosinophilia, total and Toxocara-specific immunoglobulin E (IgE) production, and in vitro cytokine production by lung cells. The numbers of eosinophils in the peripheral blood of normal and heterozygous mice peaked on days 10 and 21, although mutant mice showed eosinophilia with a peak on day 10. This indicates that the first peak on day 10 is CD4 independent and the second peak is CD4 dependent. Before infection, the levels of total IgE had no significant difference among the three groups of mice. Total and Toxocara-specific IgE in all genotypes of mice increased after infection, and was the highest in normal mice and the lowest in mutant mice. In vitro production of interleukin (IL)-5 and IL-4 by total lung cells was the highest in normal mice and the lowest in mutant mice. CD4+ and CD4- CD8- T lymphocytes, but not CD8+ T lymphocytes produced IL-5 and IL-4 when incubated with anti-CD3 monoclonal antibody (mAb) and lung-adherent cells. These results indicated that IL-5 and IL-4 were produced mainly by CD4+ cells and partly by CD4- CD8- cells, but not by CD8+ cells. In addition, cytokine production by CD4+ cells was affected by the number of CD4 molecules on their surface.

Animals↗
PubMed1998

Incidence of patent Toxocara canis infection in bitches during the oestrous cycle.

The incidence of patent Toxocara canis infection as result of reactivation of somatic larvae with subsequent tracheal migration was investigated by faecal examination during 23 oestrous cycles of 15 bitches. Blood samples were collected for determination of total and differential leukocyte counts, prolactin concentration, and Toxocara titre. Five pregnant dogs were used as controls. In the cyclic dogs there were no alterations in white blood cell counts or prolactin concentration, in contrast with the pregnant dogs, in which both variables increased, starting 10 days after onset of the luteal phase. The difference was significant at day 40 and day 60 (both p < 0.005). No significant differences were observed in the number of eosinophils or in the Toxocara antibody titre. T. canis eggs were only found in the faeces of three 1-year-old, cyclic dogs at 1, 60, and 140 days, respectively, after the onset of the luteal phase. It is concluded that cyclic beagle bitches, in which prolactin levels increase in the second half of the luteal phase, are unlikely to be at higher risk for patent T. canis infection than in other phases.

Animals↗
PubMed2007

Bottle feeding and exposure to Toxocara as risk factors for wheezing illness among under-five Amazonian children: a population-based cross-sectional study.

We investigated the prevalence and risk factors for wheezing and asthma in young Amazonian children. A population-based cross-sectional survey of 606 children aged 6-59 months was performed in two small towns in Acre State, Northwestern Brazil. Information on outcome variables (recent wheezing and medical diagnosis of asthma) and demographic, socioeconomic, environmental, maternal and nutritional variables was obtained by interviewing children's mothers or guardians. Infections with intestinal parasites and antibodies to the zoonotic nematode Toxocara were diagnosed using standard laboratory techniques. Multiple unconditional logistic regression models were used to describe associations between independent variables and outcomes. The prevalence of recent wheezing (one or more reported episodes in the past 12 months) was 42.6%, but only 19.8% of wheezing children were also reported to have a medical diagnosis of asthma (prevalence, 8.5%); 21.5% of the children examined had antibodies to Toxocara. Increased risk of asthma was independently associated with early introduction of bottle feeding, defined as <4 months of exclusive breastfeeding [adjusted odds ratio (aOR) = 2.21, 95% confidence interval (95% CI), 1.07-4.59, P = 0.033], and seropositivity to Toxocara (aOR = 2.37, 95% CI 1.17-4.77, P = 0.016), suggesting two potential targets for public health interventions.

Animals↗
PubMed2005

Persistent airway hyper-responsiveness and inflammation in Toxocara canis-infected BALB/c mice.

BACKGROUND: Infection with Toxocara canis, the roundworm of dogs, has been associated with asthmatic manifestations. Clinical symptoms such as wheezing, coughing and episodic airflow obstruction have been described for patients infected with this helminth. OBJECTIVE: In order to characterize the effect of T. canis infection on the lungs, we monitored immune responses, pulmonary pathology and lung function over a period of 60 days in BALB/c mice. METHODS: Infection was performed by a single oral administration of 1000 T. canis embryonated eggs. Airway responsiveness was measured in conscious, unrestrained mice at 7, 14, 30 and 60 days post-infection (p.i.). RESULTS: Infection of mice resulted in airway hyper-responsiveness (AHR) that persisted up to 30 days p.i. Pulmonary inflammation as well as increased levels of IgE and eosinophils in bronchoalveolar lavage (BAL) persisted up to 60 days p.i. Cytokine analysis in BAL indicated increased levels of IL-5 at day 7 and 14 p.i., whereas the levels of IL-2, IFN-gamma, IL-4 and IL-10 did not differ from those of uninfected controls. Toxocara-specific stimulation of spleen cells using recombinant TES-70 protein resulted in the induction of IL-5 at day 7 and 14 p.i. and IL-10 at day 14 p.i. Production of all other cytokines did not differ from that of uninfected controls. Evaluation of larval burden revealed that T. canis was still present in the lungs of infected mice at 60 days p.i. CONCLUSION: The presence of Toxocara larva in the lungs at 60 days p.i. following a single infection could explain the persistent pulmonary inflammation, airway hyper-reactivity, eosinophilia and increased IgE production observed in T. canis-infected BALB/c mice.

Animals↗
PubMed1988

Specificity of Toxocara ELISA in tropical populations.

The diagnosis of human infection by Toxocara canis relies heavily upon serological tests, the specificity of which can be inadequate in regions of endemic helminthiasis. When different population groups of tropical Venezuela were evaluated using ELISA based upon Toxocara excretory-secretory antigen (TcESA), solid-phase adsorption of the sera with extracts of a wide variety of non-homologous parasites revealed the existence of significant cross-reactivity. This was effectively and conveniently overcome when the test sera were incubated in the presence of the soluble parasite extracts in a competitive inhibition ELISA. The mean reduction of ELISA values caused by pre-adsorption of the sera tested was 32.2%, and that caused by competitive inhibition was 42.3%, the effects of these two procedures being strongly correlated (r = 0.83). The magnitude of the reduction was inversely proportional to the actual ELISA value (r = -0.55), and ranged from a mean of 68.0% in sera from apparently healthy individuals of medium-high socio-economic level, down to 28.1% in heavily parasitized Amazon indians. Ascaris showed the greatest degree of cross-reactivity in these tests, although under conditions of competitive inhibition even sera with high levels of antibody against this parasite could be negative in Toxocara ELISA. Western blotting revealed a major 81,400 D component that was shared between Ascaris and TcESA. Our results indicate that the competitive inhibition of cross-reactivity by soluble non-homologous parasite extracts provides a convenient and economical means of increasing the specificity of ELISA for the determination of the seroprevalence of toxocariasis in tropical populations.

Adsorption↗
PubMed1989

[Behavior and pathogenicity of larva of Toxocara canis Werner 1782 (Anisakidae) in the mouse].

To evaluate the interdependence between pathological changes and the level of infection the behaviour of Toxocara canis larvae in the host, the course of the disease as well as quality and quantity of histological changes were investigated after experimental infection with 1,000, 500, 250, and 125 larvae respectively. The main places where the larvae of Toxocara canis were found at any time after infection were musculature and brain. Regardless of the level of infection the absolute and relative number of larvae in the brain increased linearly, and parallel decreased in musculature. After the 60th day post infection the mice infected with 1,000 larvae showed compulsive movements, disturbance of equilibrium and paralysis of the hindlegs. The mice infected with 500 larvae showed similar symptoms 30 to 40 days later. Mice with weaker infections only showed slight disturbances of the general condition at the end of the trials. In the brain of all animals infected with larvae of Toxocara canis inflammatory reactions were found. Severe destructive changes in the nervous substance together with clinical symptoms were seen only in higher infected mice.

Animals↗