Abstract
Caterpillars and Moths
(Dermatologic Therapy. 2009;22:353–366) EW Hossler
Prepared by Anil Menon, MD, Stanford Wilderness Medicine Fellow, Stanford, CA, USA
The United States poison control centers reported an average of 2094 yearly calls about caterpillar stings between 2001 and 2005. Most stings involved one individual and symptoms were self-limited, but some stings have caused death and, also, infestations have created epidemics and resulted in school closures. This review article discussed medically important Lepidopterans (moths, butterflies, and caterpillars) in an effort to aid in diagnosis, identification, and treatment.
A significant portion of this article addressed each species and described its effects after exposure. Notable manifestations include cutaneous reactions and rashes termed erucism, and, when associated with systemic findings such as fever or malaise, lepidopterism. Other presentations include ocular inflammation following eye exposure to spines or hairs (ophthalmia nodosa), coagulopathy from South American Lonomia caterpillars (lonomism), ataxia from ingestion of Anaphe venata (seasonal ataxia), and arthralgias and joint degeneration termed dendrolimiasis or pararamose.
The author rightly advises that prevention is of paramount importance. This can be done by avoiding Lepidopterans, avoiding contact with caterpillars and fragmented spines that may contaminate clothing, reducing artificial lighting during epidemics, and using pesticides such as diflubenzuron to kill larvae. N,N-Diethyl-meta-toluamide has been shown to be less useful in prevention. After dermal exposure cellophane tape, duct tape, and irrigation help to remove spines.
Symptomatic treatment includes topical antipuritics, aspirin, and steroids for mild erucism while systemic antihistamines and steroids may be needed for more severe cases. In lonomism, it is important to correctly identify the caterpillar as L. obliqua or L. achelous because coagulopathy due to the latter has been successfully treated with cryoprecipitate, amicar, and fibrinogen while envenomation by the former has been exacerbated by such treatments. A horse serum antivenom has been developed and successfully used to treat L obliqua stings. Seasonal ataxia has been successfully treated by thiamine (100 mg orally every 8 hours) in a placebo-controlled study. Ophthalmia nodosa requires specialized long term care by an ophthalmologist. Similarly, dendrolimiasis with joint involvement requires specialized care and joint washouts.