Harmonia axyridis ladybug hypersensitivity in clinical allergy practice.

The imported Harmonia axyridis ladybug infests homes in northern West Virginia from fall through spring, causing allergic disease. Retrospective single-practice chart reviews were performed: (1) all skin prick tests (1400 included ladybug) in a community allergy practice over 4 years and (2) clinical analysis of 400 randomly chosen patients. The usual adult aeroallergen skin test panel included ladybug and 57 other allergens. Statistics used were contingency table analyses and the kappa-statistic for concordance. Home infestation with ladybugs was most common in rural areas but did not predict ladybug sensitization (kappa = -0.02). Ladybug sensitization and allergy occurred at all ages. Ladybug sensitization occurred with 21% frequency compared with cat at 24% frequency, cockroach at 27% frequency, and dust mites at 40% frequency. Only ladybug showed a significant (p < 0.0001) skin test sensitization decreasing from rural (30%), mixed (21%), to urban (16%) home demographics. Isolated single-positive skin tests constituted 10% of dust mites, 6% of cockroach, 6% of ladybug, and 4% of cat-positive skin tests. Skin test concordance was strongest between the pairs: ladybug-cockroach (kappa = 0.36), cockroach-dust mite (kappa = 0.29), and dust mite-cat (kappa = 0.25). Ladybug is a major allergen in endemic areas, causing rhinoconjunctivitis (8% prevalence), asthma (2% prevalence), and urticaria (1% prevalence). Ladybug skin test sensitization is more common in rural areas and is comparable in frequency and age distribution with cat and cockroach. Cockroach and ladybug have a high degree of skin test concordance. A quality commercial ladybug allergen extract and increased ladybug allergen research are needed.