Toxocara Antibody Research Articles

Serodiagnosis of Toxocaral Larval Migrans in Monkeys by Enzyme-Linked Immunosorbent Assay (ELISA) with Somatic Adult and Secretory Larval Antigens

With the introduction of an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of toxocaral larva migrans syndrome in human and experimental animals (Cypes et al., 1977, J. Inf. Dis. 135: 633-640; Ruitenberg and Knapen, 1977, J. Inf. Dis. 136 (suppl.): 267-273) one of the problems in the serodiagnosis of this infection was solved, namely the lack of a sensitive method. The use of a wide variety of antigens of somatic origin of different stages of the parasite's life cycle resolved the problem of specificity. The demonstration by de Savigny (1975, J. Parasitol. 61: 781-782) that excretory/secretory (ES) antigens obtained from in vitro-maintained L2 larvae were very specific for toxocara antibody contributed to better serodiagnosis of toxocariasis. This prompted us to reexamine sera of monkeys experimentally infected and subsequently immunized with Toxocara canis with ELISA using ES antigen. Monkeys (Macaca fasciolaris) were infected orally with 2 x 104 embryonated T. canis eggs and were later immunized by three injections of 1.5 mg adult T. canis antigen intramuscularly as was described in detail by Ruitenberg and Knapen (1977, loc. cit.). The ES antigens were obtained by in vitro maintenance of L2 larvae as described by de Savigny (1975, loc. cit.) and de Savigny and Tizard (1977, Trans. Roy. Soc. Trop. Med. Hyg. 71: 501-507). ELISA was carried out as a micro assay. For the somatic antigens the procedure was described earlier by Ruitenberg and Knapen (1977, loc. cit.), whereas for the ES antigen the following modifications were applied. The ES antigen concentration used was empirical. In our system a 1:1,000 dilution in carbonate

Serum and Vitreous Toxocara Antibody in Nematode Endophthalmitis

Five patients had a clinical diagnosis of nematode endophthalmitis and had both a serum and vitreous titer for Toxocara antibody. All five patients had a vitreous titer that was equal to or greater than the serum titer. Serum and vitreous obtained from ten other patients who had no evidence of endophthalmitis did not show this correlation. This study provides the clinician with a further understanding of the meaning of a positive enzyme-linked immunosorbent assay titer as well as an additional area for analysis in selected patients with ocular inflammation.

Clinical, Serologic, and Epidemiologic Characteristics of Ocular Toxocariasis

The clinical, serologic, and epidemiologic characteristics of 17 cases of ocular toxocariasis (OT) were studied and compared with those of a control group of 15 cases of other ocular diseases whose differential diagnosis included retinoblastoma. The prevalence and mean titers of Toxocara antibody detected by enzyme-linked immunosorbent assay were greater (P less than 0.005) for patients with OT than for the control group, but not all clinically diagnosed OT cases had detectable antibody. The prevalence of pica was significantly greater in cases than in controls (P less than 0.05). Almost all case and control patients had a history of exposure to pet dogs and cats, but recent exposure to puppies (less than 3 months old) was significantly associated with Toxocara infection in this study group.

Toxocaral larva migrans: the use of larval secretory antigens in haemagglutination and soluble antigen fluorescent antibody tests

Toxocara larval excretions and secretions collected from in vitro culture were used as antigen in passive haemagglutination and soluble antigen fluorescent antibody tests for the diagnosis of visceral larva migrans in experimental animals and man. Antibody to toxocaral secretions was detected in rabbits within 13 days of light Toxocara infection (ten larvae per kg) and within four days of heavy infection (10 4 larvae). Antibody was not detected following infection with 10 4 Ascaris suum larvae. In human sera, antibody was detected at low titre in 1 % of 100 healthy adults and in 2 % of 50 children. High titres were observed in one third of 170 patients with suspected visceral larva migrans and in 23 of 27 such patients presenting with an eosinophilia greater than 20 %. In 25 patients with ocular lesions of an undiagnosed nature, four showed significant levels of anti- Toxocara antibody.