Eosinophil sequestration and activation are associated with the onset and severity of systemic adverse reactions following the treatment of onchocerciasis with ivermectin

To investigate the role of eosinophil activation and sequestration in the d evelopment and severity of adverse reactions after the treatment of Onchoce rca volvulus infection, 40 O. volvulus-infected Ghanaians were randomized t o receive placebo or standard- or high-dose ivermectin, Subjects were exami ned for typical physiologic and clinical events before and up to 48 h after treatment, Plasma samples were tested for interleukin (IL)-5 and eosinophi l degranulation products (e.g., eosinophil-derived neurotoxin, EDN). After treatment, peripheral eosinophil counts declined in ivermectin-treated grou ps (P < .001), whereas circulating levels of IL-5 (P < .01) and EDN (P < .0 5) increased. Cumulative levels of IL-5 and EDN correlated with reaction sc ores (P < .01), High-dose ivermectin was associated with more-severe reacti ons, more-profound eosinopenia, and higher circulating levels of IL-5 and E DN, compared with the standard dose. These results suggest that eosinophil sequestration and activation/degranulation are associated with the initiati on and severity of ivermectin-associated adverse reactions.