RESUMO
The role of serum IL-4, IgE and IgA in protective immunity had been determined in 88- S. haematobium infected-individuals before and 3, 6, 9 and 12 months after treatment with a single dose of praziquantel. Before treatment, IL-4 level was found to be highly significant in all stages of infection, there was a positive correlation between IL-4 levels and egg count. Whereas serum IgE and IgA levels were significantly high in late infected group showing a negative correlation with egg count. After praziquantel treatment, IL-4 levels decreased gradually while IgE and IgA levels were significantly increased in all patients. At 9 and 12 months, viable ova were detected in 11 cases (12.5%), they were re-infected after treatment showing an increase in IL-4 levels, and a decrease in both serum IgE and IgA. These results indicate that IL-4 plays an important role in suppression of severe inflammatory responses associate with persistence of the parasitic stages. Also, serum IgE and IgA participate in protective immunity against S. haematobium infection. It may be essential to administer a second dose of praziquantel to all persons living in endemic areas who are likely to be in contact with infested water.