Background: Lepidopterism refers to moth- or butterfly-associated illness, including contact dermatitis, urticaria, and occasional systemic reactions. Lepidopterism outbreaks are rare.
Objective: To investigate a lepidopterism outbreak associated with caterpillars of the Douglas-fir tussock moth (DFTM; Orgyia pseudotsugata) among Boy Scouts attending summer camp in New Mexico.
Methods: Retrospective cohort analysis; environmental investigation.
Results: Attendees were primarily male (100/107; 94%) and less than 18 years old (82/107; 77%). Itch, rash, or hives were reported by 56 of 102 (55%) of campers. Patients were more likely to report direct caterpillar contact (relative risk [RR]: 2.7; 95% confidence interval [CI], 1.3-5.5); playing a caterpillar-flicking game (RR: 1.9; 95% CI, 1.1-3.4); and sleeping at campsite 6, where caterpillars were most numerous (RR: 1.7; 95% CI, 1.3-2.4). All patients recovered.
Limitations: Data on disease status and risk factors were collected retrospectively.
Conclusion: Modifying behaviors associated with lepidopterism and avoiding areas of heavy infestation can reduce illness risk.