Parasitic helminth infections may protect against allergic airway inflammation and have been associated with a reduced risk of atopy.
The helminth Trichuris suis (pig whipworm) has demonstrated efficacy in treatment of inflammatory bowel disease.
The authors conducted a double-blind, placebo-controlled trial in which 100 subjects age 18 to 65 years with grass pollen-induced allergic rhinitis were assigned to ingest 8 doses with 2500 live T suis ova or placebo.
Treatment with T. suis ova caused transient diarrhea peaking at day 41 in 33% of participants and increased eosinophil counts and T. suis-specific IgE, IgG(4) and IgA.
There was no significant change in symptom scores and wheal reaction on skin prick testing with grass or other allergens.
The authors concluded that treatment with the helminth T. suis induced a clinical and immunologic response as an infection, but had no therapeutic effect on allergic rhinitis.
Trichuris suis ova therapy for allergic rhinitis: A randomized, double-blind, placebo-controlled clinical trial. Bager P, Arnved J, Rønborg S, Wohlfahrt J, Poulsen LK, Westergaard T, Petersen HW, Kristensen B, Thamsborg S, Roepstorff A, Kapel C, Melbye M. J Allergy Clin Immunol. 2009 Oct 2.
Image source: Trichuris egg in stool sample (40x). Wikipedia, GNU Free Documentation License, Version 1.2.