Sir.—I read with interest the report by Hamrick and Moore1 on giardiasis causing urticaria in a child. The incidence of parasitic infections is high among Brazilian children. Ascaris lumbricoides and Trichuris trichiura eggs are frequently found in stool specimens. Giardia lamblia infection is also endemic in our area.
Patients with chronic or acute urticaria are routinely screened for the presence of ova or cysts in their stool specimens. It is not uncommon to implicate the parasite as cause of urticaria. I have seen G lamblia, Entamoeba histolytica, and A lumbricoides causing urticaria.
An observation that has puzzled me was that a patient with urticaria and ascariasis had had an exacerbation of the urticaria with angioedema soon after treatment of the helminthiasis. The reaction was severe but not systemic and subsided with subcutaneous epinephrine.
I agree with Hamrick and Moore that urticaria may occur with a massive absorption of