In a transversal study on a sample of 386 children and adolescents from an outpatient clinic for filariasis in Recife, Northeast Brazil, the frequency of anti-Toxocara antibodies and its relation to age, gender, number of peripheral eosinophils, Wuchereria bancrofti microfilariae and intestinal helminths was determined. The total anti-Toxocara IgG antibody frequency was 39.4%, by ELISA technique. The difference in frequency between males (40.1%) and females (37.6%) was not statistically significant. The 6 to 10-year-old subset presented the highest frequency of anti-Toxocara antibodies (60%), and within this age group there was a statistically significant male bias. There was also a significant association between the number of eosinophils and the presence of anti-Toxocara antibodies. Intestinal parasite frequency was 52.1%, but no association was found between this data and the presence of anti-Toxocara antibodies. In the present sample, 42.2% of the patients were Wuchereria bancrofti carriers, however, again this was not associated with the presence of anti-Toxocara antibodies. In conclusion, anti-Toxocara antibodies were highly prevalent in this sample. The present data show that there is no cross correlation between anti-Toxocara IgG antibody and the presence of intestinal helminths and filariasis.

To evaluate the prevalence of toxocariasis in children in Jaboatão dos Guararapes, Pernambuco in northeastern Brazil, 215 serum samples were examined by an enzyme-linked immunosorbent assay (ELISA) using a recombinant Toxocara canis antigen. In the ELISA, 26 (12.1%) of 215 subjects were positive. In a dot-blot assay using 53 of 215 serum samples, the diagnostic results correlated with those obtained by the ELISA. Moreover, it has been confirmed that the recombinant T. canis antigen was highly specific for toxocariasis by ELISA using serum samples positive for antibody to Ascaris lumbricoides. Considering the specificity of the recombinant antigen to toxocariasis, the ELISA or dot-blot assay using the recombinant T. canis antigen is recommended in tropical and sub-tropical regions where various parasitic infections are commonly endemic.

A group of youngsters (4-18 years old) in northeast Brazil

Immunodetection of human IgG anti-Toxocara canis was developed based on ELISA and on the use of polysiloxane/polyvinyl alcohol (POS/PVA) beads. A recombinant antigen was covalently immobilized, via glutaraldehyde, onto this hybrid inorganic-organic composite, which was prepared by the sol-gel technique. Using only 31.2 ng antigen per bead, a peroxidase conjugate dilution of 1:10,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates. However, the difference between positive and negative sera mean absorbances was larger for this new glass based assay. In addition to the performance of the POS/PVA bead as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application

We conducted a survey of the prevalence of Toxoplasma gondii infection in children living in Jaboatdo dos Guararapes, Pernambuco, Brazil from 1998 to 1999. This city is situated adjacent to Recife, capital of the state of Pernambuco. We determined the prevalence of specific anti-T gondii IgG antibodies in 196 individuals from 2 to 16 years of age. Individuals who were IgG antibody negative also underwent specific anti-T gondii IgM testing to detect recent infection with the parasite. Seroprevalence was 79.1%, and high titers of IgG antibody were observed in 49% of positive subjects. The prevalens of antibodies to T gondii increased with age, with a multiple correlation coefficient (R) of 0.709; however, there was no significant differencein antibody status by sex. Out of 47 children who did not have specific anti-T gondii IgG antibody, 4 were determined by specific anti-T gondii IgM antibody analysis to have been recently infected. Stool was examined for soil-transmitted helminth eggs to assess the frequency of soil contact in the entire study population. Stool examination in the population revealed that soil-transmitted helminthiases was highly endemic, with an infection rate of 85.2%in this area. These results suggest that the primary mode of T gondii transmission to humans is through contact with soil.