Effect of ivermectin on allergy-type manifestations in occult strongyloidiasis.

BACKGROUND: The immunomodulatory effects of helminths have been well described. However, there is a relative lack of literature regarding the link between parasites and allergic diseases. A number of patients with allergic symptoms have positive serologic test results for Strongyloides stercoralis. OBJECTIVE: To identify patients with allergy-type symptoms and coexisting Strongyloides infection and to analyze the effect of Strongyloides eradication therapy with ivermectin on these symptoms. METHODS: The medical records of our allergy clinic sites were reviewed for Strongyloides test results between January 2011 and October 2014. Each allergy-type symptom was assessed separately with regard to improvement after ivermectin therapy. RESULTS: Among the 1,446 patients who had Strongyloides serologic tests ordered, 127 (8.8%) had positive test results. Eighty-four patients had follow-up data regarding allergy-type symptoms after ivermectin treatment. Among these, 52 patients (61.9%) reported skin-related problems (pruritus, urticaria, angioedema, and/or rash). Forty-nine patients (58.3%) had asthma, and 73.8% had allergic rhinoconjunctivitis. Although respiratory symptoms typically did not respond to ivermectin treatment, 24 of 48 patients (50%) with skin symptoms reported a significant subjective improvement of symptoms after ivermectin treatment. Peripheral eosinophil counts significantly decreased after ivermectin treatment from 450 to 200/µL (P < .001). CONCLUSION: Serologic testing for strongyloides may be indicated for patients with allergy-type symptoms and a suggestive exposure history. Patients with strongyloidiasis and primarily cutaneous symptoms experienced significant symptomatic improvement after ivermectin therapy.