CONCURRENT PARASITIC INFECTIONS IN ONCHOCERCIASIS AND THE OCCURRENCE OF ADVERSE REACTIONS AFTER IVERMECTIN TREATMENT

Ivermectin is a safe, effective, and relatively well-tolerated drug fo r the treatment of human onchocerciasis. However, due to side effects of the drug, large-scale ivermectin distribution without medical super vision is not recommended. The mechanisms involved in the pathogenesis of ivermectin-induced adverse reactions are not yet known. Since onch ocerciasis patients are likely to have concurrent parasitic infections , we investigated whether side effects that occur after ivermectin tre atment could be related to the presence of parasite eggs and cysts in stool samples prior to treatment. One hundred twenty-nine onchocercias is patients were treated with a single dose of ivermectin (150 mug/kg) and side effects were graded according to the classification of Green e and others. Stool samples were collected before and three days after treatment. A high percentage (80.5%) of the patients reported adverse effects (57% mild, 14.1% moderate, and 9.4% severe reactions). Most ( 95.1%) of the patients had one or more concurrent parasitic infections . No relationship could be found between the occurrence and extent of side effects and the severity of concurrent intestinal parasitic infec tions. However, side effects were significantly correlated with pretre atment microfilarial counts. Ivermectin treatment did not induce signi ficant short-term changes in Trichuris trichiura or Schistosoma manson i egg counts. However, a significant reduction in Ascaris lumbricoides egg counts and Entamoeba coli cyst loads was observed; a cure rate of 46% for cysts was reached. In contrast, hookworm egg production incre ased after ivermectin treatment. Further studies are required to verif y ivermectin-induced changes in cyst and hookworm loads as well as the significance of these findings.