SIDE REACTIONS FOLLOWING IVERMECTIN THERAPY IN HIGH-DENSITY BANCROFTIAN MICROFILARAEMICS

Side reactions following ivermectin treatment were evaluated in sixty males with high density bancroftian microfilaremia (GM 1388/ml). Follo wing a single oral dose of ivermectin of different strengths (20, 50, 100 or 200 mug/kg), microfilariae clearance and side reactions were mo nitored in a double blind fashion. Microfilaria levels fell rapidly af ter ivermectin administration in all dosage groups and 98% of pretreat ment microfilariae was cleared after 12 h of treatment. The rate of mi crofilaria (mf) clearance was slower with 20 mug/kg than with the high est dose (200 mug/kg) administered. Forty-six patients (77%) became am icrofilaraemic within 2 weeks of treatment. Side reactions were noted in 97% of cases. The most common reactions were fever, headache, weakn ess, myalgia and cough which appeared by 12 h and subsided by 72 h fol lowing treatment. The frequency and intensity of side reactions were r elated to pretreatment mf densities and were independent of the dose a dministered. Unusual side reactions were noted in a few patients with high density microfilaraemia. These included intense cough, shortness of breath, blood tinged mucoid expectoration associated with patchy pn eumonitis of the lung. Itchy rashes, lymphatic nodules and raised alka line phosphatase level were also observed in some patients. These side reactions were transient, self limiting and were not serious enough t o warrant any treatment. These exaggerated unusual reactions were poss ibly due to allergic response of the susceptible host to rapid killing of large number of microfilarae.