Interação e associação dos fatores de risco entre Toxocara sp. e Giardia duodenalis e alergia em crianças atendidas no Hospital de Clínicas da Universidade Federal de Uberlândia (HC-UFU), Uberlândia-MG

Abstract

Epidemiological studies conducted around the world suggest that infection by Toxocara sp. and Giardia duodenalis may contribute to the development or exacerbation of atopic diseases, especially in children. This study analyzed the seroprevalence of toxocariasis and the prevalence of G. duodenalis in atopic and non-atopic children treated at the pediatric clinic of the Clinical Hospital of the Federal University of Uberlândia, to identify possible correlations with epidemiological factors. Blood samples were collected from 122 atopic children and 51 non-atopic children between 6 and 15 years old who underwent previous skin-prick testing to confirm atopy, as well as clinical examinations. Risk or protective factors for toxocariasis and giardiasis were analyzed by means of a questionnaire. Serum samples were tested for the presence of antibodies of anti-Toxocara IgG, anti-Giardia IgG, serum anti-Giardia IgA, and Dermatophagoides pteronyssinus-specific IgE, using ELISA. The avidity index of anti- Toxocara IgG antibodies was determined to check whether the infection was recent or delayed. Stool samples were also collected to check for the presence of cysts and/or trophozoites of G. duodenalis. Fecal extracts were produced to perform the ELISA for fecal anti-Giardia IgA. The seroprevalence of Toxocara sp. in atopic children was 19.7%. No significant association was found between the infection and possible factors in atopic children. Most of the samples showed a high avidity index, indicating long-standing infection. The prevalence of G. duodenalis in atopic children was 5.7%. The only variable that was significantly associated with giardiasis in atopic children was having first-degree relatives with allergy. A comparison of the levels of D. pteronyssinus-specific IgE among individuals serologically positive and negative for Toxocara sp. and positive and negative for G. duodenalis showed no statistically significant difference. The Kappa correlation between serum anti-Giardia IgA, fecal anti-Giardia IgA and anti-Giardia IgG was low, denoting poor reproducibility. Although no statistical association was found a between human toxocariasis and atopic disease, this study revealed a high seroprevalence of Toxocara sp in children, which may indicate environmental contamination with the parasite s eggs in the environment where these children live. As for giardiasis, the only statistically related variable was the fact that atopic children have first-degree relatives also with atopy. It is speculated that in this study, atopy and parasitism may not have a relation; however, further studies are needed.