[Changes in the peripheral leukocytes of onchocerciasis patients treated with consecutive doses of ivermectin]

The purpose of this investigation, which utilized a single-blind study with placebo, was to evaluate the peripheral leukocyte count in onchocerciasis patients treated with ivermectin. Eighty-three male patients between the ages of 12 and 60, all with moderate or severe onchocerciasis infections (but otherwise in general good health), were selected from three villages from the southern onchocerciasis endemic area of Chiapas, Mexico. All onchocerciasis patients were randomly assigned to either the ivermectin group or a placebo group in a three to one ratio, respectively. Sixty-two patients from the ivermectin group received five single oral doses of ivermectin between 150 and 220 mcg/kg (one every six months), and placebo pills of identical appearance were given to 21 patients from the placebo group. Physical, ophthalmological, and laboratory exams were performed on all patients in this study. Skin and ocular microfilaria were stimulated in all patients. Results have indicated that ivermectin induced a decrease in the total number of peripheral leukocytes to the extent of about 300 to 500 cells after each drug intake. In the majority of the cases, the reduction was due to a decrease in the total number of eosinophils; the number of neutrophils, lymphocytes, and monocytes remained at the same level after treatment. These results strongly suggest that the eosinophilia observed in the prestudy of those individuals with onchocerciasis could have induced leukocytosis (the eosinophilia decreasing significantly after administering ivermectin).