Onchocerciasis in a nonendemic population: Clinical and immunologic assessment before treatment and at the time of presumed cure

Although suppressive therapy for onchocerciasis with intermittent ivermecti n prevents the development of pathology in endemic populations, the clinica l and immunologic effects of therapy in the absence of continued exposure a re unknown. To address this question, 14 patients treated with ivermectin f or onchocerciasis acquired >10 years ago during temporary residence in Afri ca were reevaluated. None had evidence of continued infection or pathology at follow-up. Although eosinophilia, serum IgE, and antifilarial antibody l evels decreased after ivermectin therapy, none of these parameters was usef ul in predicting the resolution of symptoms in infected patients. Periphera l blood mononuclear cells isolated from patients at follow-up were more res ponsive to parasite antigen in vitro, which is as assessed by proliferation and production of interferon-gamma and interleukin (IL)-5. In contrast, an tigen-induced levels of IL-10 were significantly decreased at follow-up, co nsistent with diminished down-regulatory factors rather than a switch from type 2 to type 1 immune responses.