Toxocara Antigens Research Articles

A retrospective study of ocular toxocariasis in Japan: correlation with antibody prevalence and ophthalmological findings of patients with uveitis.

To classify the clinical characteristic of ocular toxocariasis in Japan, the prevalence of antibodies to Toxocara antigens was examined in patients with uveitis of unknown aetiology. From 1982 to 1993, serum specimens of 383 cases and intraocular fluid samples of 22 cases were serologically screened for Toxocara infection with five immunodiagnostic tests. Fifty-five sera and 11 intravitreous fluid samples were estimated to have significantly high antibody levels against larval excretory-secretory (ES) antigens of T. canis. Eight cases were positive in both serum and vitreous fluid, and three were positive only in the vitreous fluid. Among the 58 antibody positive samples, 20 cases were omitted due to a lack of detailed description of ocular findings. The remaining 38 cases are described in this study. Of these 38 cases, 34 (89%) were older than 20 years of age. Ocular lesions were located in the posterior fundus in 11 cases, in the peripheral fundus in 18 cases, and in both areas in seven cases. Of the eight cases in which papillary oedema or redness was observed, chorioretinal lesions were also present in seven of them. Tractional retinal detachment was present in five cases. These observations suggest that ocular toxocariasis in Japan has a different clinical profile compared with those in the other countries, and indicate a need for revised classification of ocular toxocariasis.

A retrospective study of ocular toxocariasis in Japan: correlation with antibody prevalence and ophthalmological findings of patients with uveitis

To classify the clinical characteristics of ocular toxocariasis in Japan, the prevalence of antibodies to Toxocara antigens was examined in patients with uveitis of unknown aetiology. From 1982 to 1993, serum specimens of 383 cases and intraocular fluid samples of 22 cases were serologically screened for Toxocara infection with five immunodiagnostic tests. Fifty-five sera and 11 intravitreous fluid samples were estimated to have significantly high antibody levels against larval excretory–secretory (ES) antigens of T. canis. Eight cases were positive in both serum and vitreous fluid, and three were positive only in the vitreous fluid. Among the 58 antibody positive samples, 20 cases were omitted due to a lack of detailed description of ocular findings. The remaining 38 cases are described in this study. Of these 38 cases, 34 (89%) were older than 20 years of age. Ocular lesions were located in the posterior fundus in 11 cases, in the peripheral fundus in 18 cases, and in both areas in seven cases. Of the eight cases in which papillary oedema or redness was observed, chorioretinal lesions were also present in seven of them. Tractional retinal detachment was present in five cases. These observations suggest that ocular toxocariasis in Japan has a different clinical profile compared with those in the other countries, and indicate a need for revised classification of ocular toxocariasis.

Epidemiologic approach to human toxocariasis in western France.

Toxocara canis is a common parasite in puppies. The danger to human health has not been properly established. We estimated the current incidence of this pathogen in two western districts of France, Loire-Atlantique and Maine et Loire. Blood samples from 1836 eosino-philic patients were collected and tested by an enzyme-linked immunosorbent assay (ELISA) excretory-secretory Toxocara antigen test. We obtained positive results in 22% of the cases and highly positive results in 7%. The ELISA data seemed to be age-dependent, with older patients having more positive results (P < 0.0001). The interlaboratory distribution of positive test results was statistically significantly different (P < 0.0001), suggesting regional sources. The main clinical expressions of toxocariasis were: asthenia, gastric pain, and pulmonary disease. Individual and collective surveys of this zoonotic disease need to be carried out.

Human toxocariasis in a rural community.

A questionnaire and serologic survey of a Pennsylvania community revealed that 23 (54%) of 43 study participants had antibody titers to Toxocara canis (enzyme-linked immunosorbent assay test [ELISA]) in the range defined as positive (greater than or equal to 1:32). Age-specific seropositivity rates were highest among adults (greater than or equal to 18 years). Positive titers ranged from 1:32 to 1:512. Seropositivity did not cluster by family, and seropositivity rates were significantly higher than those of a control group. Physical examination and laboratory tests designed to detect clinical signs of toxocariasis were performed on individuals with positive ELISA titers. Nine of 23 had a history of pica, seizures, or chronic pulmonary symptoms; however, physical examination revealed no abnormalities. Although medical examination and laboratory tests revealed a few abnormalities, neither the visceral larva migrans syndrome nor the ocular lesions characteristic of those produced by Toxocara sp were observed in any individual. We conclude that although certain populations may have high seropositivity rates to Toxocara antigens, indicating previous infection, clinical diseases may be uncommon.

Toxocara and ascaris infection in British pigs: a serological survey.

A serological survey of growing pigs from farms throughout Great Britain revealed that antibodies to toxocara and ascaris larval antigens were present in 4.5 per cent and 39.3 per cent respectively. Heavy infection with toxocara occurred only rarely and it is considered that this parasite is unlikely to be an important cause of chronic focal interstitial hepatitis. Antibodies to both nematodes were detected more frequently in heavy hogs than in pigs of lighter weight. Reginal differences in the prevalence of antibodies were also observed.

DISTRIBUTION AND DIAGNOSIS OF DIROFILARIASIS AND TOXOCARIASIS IN AUSTRALIA

SUMMARY: The prevalence of Dirofilaria immitis infection in dogs continues to increase in the temperate east coast zone of Australia (and is extending further south into New South Wales and Victoria). However, the infection rate has not changed in the tropics over the past 10 years where it would appear that a maximum infection rate of 90% occurs in a given Australian dog population. Twelve percent of Brisbane dogs had occult dirofilariasis and it is suggested that the proportion of occult infections was probably higher in the tropics. Dogs of all breeds appear equally susceptible to D. immitis with infection being more common in older male dogs. The level of microfilaraemia was, occasionally, proportional to the number of heartwprms per dog. Toxocara canis was present in about 75% of dogs from all areas studied except in Central Australia where the level of infection was much lower.Immunodiagnosis of D. immitis and T. canis with high specificity and sensitivity was achieved by cyanogen bromide indirect fluorescent antibody and cell‐mediated immunity tests using parasite antigens purified by affinity chromatography. These tests enabled occult dirofilariasis to be differentiated from unrelated canine cardiac and pulmonary failure. Such immunodiagnosis can aid in the early diagnosis of dirofilariasis particularly in situations where no circulating microfilariae can be detected.The prevalence of serum antibody in man to purified Dirofilaria and Toxocara antigens was proportional to the incidence of respective canine infections at each location.

DISTRIBUTION AND DIAGNOSIS OF DIROFILARIASIS AND TOXOCARIASIS IN AUSTRALIA.

The prevalence of Dirofilaria immitis infection in dogs continues to increase in the temperate east coast zone of Australia (and is extending further south into New South Wales and Victoria). However, the infection rate has not changed in the tropics over the past 10 years where it would appear that a maximum infection rate of 90% occurs in a given Australian dog population. Twelve percent of Brisbane dogs had occult dirofilariasis and it is suggested that the proportion of occult infections was probably higher in the tropics. Dogs of all breeds appear equally susceptible to D. immitis with infection being more common in older male dogs. The level of microfilaraemia was, occasionally, proportional to the number of heartwprms per dog. Toxocara canis was present in about 75% of dogs from all areas studied except in Central Australia where the level of infection was much lower. Immunodiagnosis of D. immitis and T. canis with high specificity and sensitivity was achieved by cyanogen bromide indirect fluorescent antibody and cell-mediated immunity tests using parasite antigens purified by affinity chromatography. These tests enabled occult dirofilariasis to be differentiated from unrelated canine cardiac and pulmonary failure. Such immunodiagnosis can aid in the early diagnosis of dirofilariasis particularly in situations where no circulating microfilariae can be detected. The prevalence of serum antibody in man to purified Dirofilaria and Toxocara antigens was proportional to the incidence of respective canine infections at each location.

Larva-specific antibodies in patients with visceral larva migrans.

Seven of 10 patients with visceral larva migrans (VLM) had serum precipitating antibodies specific for larval antigens of Toxocara canis as determined by double diffusion in agar. Such antibodies were absent in 114 normal adults and 25 patients with collagen disease. Precipitation of ascarid components by C-reactive protein resulted in false-positive reactions, but this precipitation was readily prevented by appropriate absorption of sera before testing. A more sensitive assay, the enzyme-linked immunosorbent assay, revealed high titers of antibodies to larvae of Toxocara in all patients with VLM; the log2 titer ranged from 9 to 14. Five of eight household relatives of these patients and four children who had had VLM two to four years before testing had titers of 6-12. Of the 114 normal adults, 105 had titers of 0-2; nine had titers of 3-8. Of the 25 patients with collagen disease, 23 had titers of 0, and two had titers of 4 and 6, respectively. Additional studies of those patients indicated that infection with Toxocara can be distinguished serologically from ascariasis, filariasis, and trichinellosis.

Hemagglutination test for the detection of antibodies specific for Ascaris and Toxocara antigens in patients with suspected visceral larva migrans.

"Hemagglutination Test for the Detection of Antibodies Specific for Ascaris and Toxocara Antigens in Patients with Suspected Visceral Larva Migrans" published on May 1974 by The American Society of Tropical Medicine and Hygiene.

Precipitin reactions in monkeys ( Macaca sinica) experimentally infected with Toxocara canis and in children with visceral larva migrans syndrome

Six monkeys ( Macaca sinica) were experimentally infected with Toxocara canis ova and their humoral antibody response was studied by immuno-diffusion precipitin tests using as antigens saline extracts of embryonated eggs and adult worms of T. canis and Ascaris lumbricoides respectively. In addition, saline extracts of adult worms of Ascaridia galli and Ancylostoma caninum were used to elucidate the comparative serological cross-reactivity among T. canis, A. lumbricoides, A. galli and A. caninum. The monkey sera revealed a minimum of 4 to 5 species specific antibodies and at least one group antibody specific to a common antigen component shared by T. canis and the related ascaroids, A. lumbricoides and A. galli. The specific antigens were present mainly in Toxocara embryonated egg extracts while the ascaroid group specific component was present in the Toxocara adult worm extracts. Both types of antigens differed in their electrophoretic mobilities. Fifty-three serum samples from children with larva migrans syndromes were examined for precipitins to adult and embryonated egg extracts of Ascaris lumbricoides and of Toxocara canis. A specific precipitin reaction consisting of a minimum of two overlapping bands against Toxocara egg antigen was observed in the sera of 10 children. These sera also showed an ascaroid group specific precipitin reaction consisting of a minimum of one band with the antigens of Toxocara and Ascaris. The sera of seven children showed a reaction consisting of at least one with the A. lumbricoides antigens only. Six sera showed an ascaroid group specific reaction consisting of one common band with the adult worm and egg extracts of A. lumbricoides and T. canis antigens.

Visceral larva migrans. A discussion based on review of the literature.

Visceral Larva Migrans (VLM), a syn drome occurring mainly in young children, is characterized not only by chronic eosino philia, hepatomegaly, hyperglobulinemia, but at times by involvements of lung, eye, central nervous system, heart, skin or other organs as a consequence of local larval mi grations. That Toxocaral infection is the most usual cause is now well established.As a rule the course is benign but pro longed, though a few affected children have died.Diagnosis is essentially clinical. Definite proof can be established only by demon stration of the presence of larvae in the tissue. Recent work on serologic diagnostic technics and intradermal tests with Toxocara antigen are suggestive of future use fulness.No specific treatment is yet available. Di ethylcarbamazide has been tried without ap preciable effect on the eosinophilia. Recent studies indicate that thiabendazole may be of benefit.Preventive measures are of the utmost importance.

Toxocara skin sensitivity tests and other observations in animals experimentally infected with Toxocara canis

10 white mice and 3 rhesus monkeys were used in an experiment to demonstrate the specificity of Toxocara skin sensitivity tests in the presence of infection with T. canis. 4 of the mice were used as controls, being either infected and tested with normal saline, or uninfected and tested with antigen; one of the monkeys remained uninfected but was tested with antigen. Injection of saline was used as a control throughout the experiment with the monkeys. The results show that negative skin reactions were obtained in all animals before infection with eggs of T. canis, but positive reactions occurred after variable periods in the animals infected, though not in the controls. The time of conversion of the skin test did not appear to depend on dosage. We conclude that the intradermal test with Toxocara antigen is specific for infection with T. canis and is therefore a valuable diagnostic test. The total white cell counts and eosinophil levels were recorded at intervals in the monkeys, and an increase in both was noted, reaching a peak the 3rd post-infection week and declining thereafter. No changes were observed in the total plasma proteins or in the albumin/globulin ratio. Inconclusive results were obtained with the filarial complement fixation test performed on the sera of the infected monkeys.

An evaluation of passive cutaneous anaphylactic reactions with Trichinella and Toxocara antibody-antigen systems.

SummaryThe test for passive cutaneous anaphylaxis (PCA) proved relatively simple and easy to perform. Within limits, the minimal amount of challenge Trichinella antigen was dependent on the amount of antibody used for sensitization. The optimal concentrations of Trichinella and Toxocara antigens to use in PCA tests with these experimental infections were determined. Studies with rabbit and guinea pig antisera indicate that antibodies involved in PCA reactions may differ from those involved in bentonite flocculation or hemagglutination tests. PCA reactions with heterologous antigens are common. The simplicity of the procedure is considered of distinct value and advantageous, but the amount of antigen required for a reaction and the possibility of cross-reactions are drawbacks.

Hemagglutination Tests with Ascaris Antigens

Summary Antisera against Ascaris lumbricoides var suum, Ascaris lumbricoides, Toxocara canis, and Toxocara cati were prepared in rabbits by injection of lyophilized antigen and infection with viable eggs. These antisera cross-reacted with Ascaris and Toxocara antigens in hemagglutination tests. Absorption with heterologous antigen removed cross-reacting antibodies and produced generic specific antisera. Serum obtained by injection of antigen, showed higher titers than sera obtained by infection with viable eggs. Antisera prepared against polysaccharide whole-worm antigen obtained from human and pig ascarid worms, cross-reacted with antigen prepared from these 2 worms. Absorption of these sera with both homologous and heterologous antigens reduced the titers to 0. From the data, we concluded that crude polysaccharide antigen does not exhibit species specificity. Antigens prepared from saline extracts of whole worm or tissues of pig ascarids are effective antigens in the hemagglutination test, and without preliminary absorption, antigens of Toxocara or Ascaris worms cross-react with antisera prepared against these species.