[An unusual case of systemic toxocariasis].

Systemic toxocariasis generally causes fever, liver enlargement and lymph node swelling. This is an unusual case report which was initially confused with juvenile rheumatoid arthritis due to the presence of fever, arthralgias, arthritis of the smaller joints, important leukocytosis and hypergammaglobulinemia, besides testing positive for rheumatoid factor type IgM. After finding severe eosinophilia in both the patient's blood as well as in the bone marrow, systemic toxocariasis was diagnosed also finding very high levels of antibodies against Toxocara canis using the ELISA technique. Briefly discussed are the clinical and laboratory data, and the management of systemic toxocariasis and the possible origin of the rheumatoid factor in this disease.