2010 Volume 120 Issue 6 Pages 1179-1186
The gypsy moth (Lymantria dispar) is a member of the family Lymantriidae, which is found not only in Japan but also throughout the northern hemisphere. Infestations of this moth sometimes erupt into large numbers, and it is a well-known forest pest. First instar larvae of gypsy moths have poisonous hairs that cause dermatitis, although there are only a few reports of the problem. Moreover, community-wide outbreaks of dermatitis have not been previously reported in Japan. Between May and June 2008, we treated 58 caterpillar dermatitis patients caused by gypsy moth caterpillars that had significantly increased in number in Kuzumaki Town in Iwate Prefecture. The patients had pruritic, erythematous, papular, and occasionally vesicular lesions on exposed areas of the body such as the neck and arms. A questionnaire survey given to the residents of Kuzumaki Town revealed that 926 people had dermatitis thought to be caused by gypsy moth caterpillars. The fact that first instar larvae of gypsy moths cause dermatitis should be more widely recognized.