Persistence of specific antibody response in different experimental infections of mice with Toxocara canis larvae.

Anti-Toxocara antibody production and persistence were studied in experimental infections of BALB/c mice, according to three different schedules: Group I (GI)-25 mice infected with 200 T. canis eggs in a single dose; Group II (GII) 25 mice infected with 150 T. canis eggs given in three occasions, 50 in the 1st, 50 in the 5th and 50 in the 8th days; Group III (GIII)-25 mice also infected with 150 T. canis eggs, in three 50 eggs portions given in the 1st, 14th and 28th days. A 15 mice control group (GIV) was maintained without infection. In the 30th, 50th, 60th, 75th, 105th and 180th post-infection days three mice of the GI, GII and GIII groups and two mice of the control group had been sacrificed and exsanguinated for sera obtention. In the 360th day the remainder mice of the four groups were, in the same way, killed and processed. The obtained sera were searched for the presence of anti-Toxocara antibodies by an ELISA technique, using T. canis larvae excretion-secretion antigen. In the GI and GII, but not in the GIII, anti-Toxocara antibodies had been found, at least, up to the 180th post-infection day. The GIII only showed anti-Toxocara antibodies, at significant level, in the 30th post-infection day.

Clinical and laboratorial features of visceral toxocariasis in infancy.

Forty children with a diagnosis of Visceral Toxocariasis were evaluated prospectively from February 1982 to June 1989. Diagnosis was established by clinical, laboratory and serological (ELISA - ES Toxocara canis antigen) evaluations. A great clinical polymorphism was found in our patients, ranging from unspecific or absent manifestations to an exuberant symptomatology. The laboratory findings were: leukocytosis, eosinophilia and elevation of serum gammaglobulin and isohemagglutinin levels. No significant relationship between clinical findings and laboratory parameters was found. Serology (ELISA) was a method of great diagnostic support but did not show a correlation with clinical and laboratory findings in this study. There was a significant relationship between pulmonary manifestations and the presence of signs and/or symptoms, when the patients were sent to us. Our findings, especially the high incidence of pulmonary manifestations, suggest that Visceral Toxocariasis has to be included in the differential diagnostic of children with pulmonary manifestations, characteristic epidemiological data and associated eosinophilia.