The Use of Ivermectin to Kill Ixodes Scapularis Ticks Feeding on Humans

• Published in: Wilderness & environmental medicine Vol. 25; no. 1; pp. 29 - 34
• Main Authors: Sheele, Johnathan M., Ford, Lucie R., Tse, Adele, Chidester, Benjamin, Byers, Peter A., Sonenshine, Daniel E.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA Elsevier Inc 01.03.2014; SAGE Publications
• Subjects: Administration, Oral; Adult; Animals; Emergency; Female; Humans; ivermectin; Ivermectin - administration & dosage; Ivermectin - pharmacology; Ixodes - drug effects; Ixodes scapularis; Lyme disease; Male; Mortality; Nymph - drug effects; prevention; tick; tick-borne disease; Young Adult; Lyme disease; tick-borne disease; tick; ivermectin; Ixodes scapularis; prevention
• ISSN: 1080-6032; 1545-1534; 1545-1534
• DOI: 10.1016/j.wem.2013.09.008

The purpose of this study was to determine whether 400 µg/kg oral ivermectin is able to kill Ixodes scapularis nymphs and adult female ticks feeding on humans. Ten study subjects each wore 2 ostomy bags, the one containing 24 I scapularis nymphs, and the other containing 24 I scapularis adult females. Twenty-four hours after the ostomy bags were attached, study subjects received either 400 µg/kg ivermectin or placebo. Thirty hours after the ivermectin or placebo was consumed, the ticks were removed, and mortality determined in a double-blinded manner. Eleven percent of the I scapularis nymphs attached in the ivermectin group compared with 17% in the placebo. Mortality for the I scapularis nymphs that attached at the time of removal was 55% in the ivermectin group and 47% in the placebo group. Mortality for the I scapularis nymphs 5 days after removal was 92% in the ivermectin group and 88% for the placebo. Three percent of the I scapularis adults attached in the ivermectin group compared with 9% in the placebo group. Mortality for I scapularis adults was 0% on day 3 and 33% on day 8 for both the ivermectin and placebo groups. There were statistically insignificant differences in the mortality rates between I scapularis nymphs and adults exposed to ivermectin or placebo. There were a high number of ticks that died in both groups but the data do not support our hypothesis that ivermectin can kill I scapularis. The study was not designed to determine whether it could prevent the transmission of tick-borne illness.