Dermanyssus gallinae infestation: an unusual cause of scalp pruritus treated with permethrin shampoo.

Dermanyssus gallinae is a blood parasite of wild birds, but it is also a pest in the poultry industry. It occasionally bites mammals and thus rarely creates skin problems such as itching, papules, vesicles, and dermatitis. A 92-year-old man presented with severe itch on his head, particularly at night. He had been misdiagnosed with senile pruritus and treated with antihistamines and topical corticosteroids with temporary relief of the symptoms. On the basis of clinical and parasitological findings, D. gallinae dermatitis was diagnosed. Decontamination of the patient's immediate environment was not helpful. The patient was successfully treated using a 1% permethrin shampoo once a week for 2 weeks. During 3 months of follow-up he was free of symptoms. The case is of significance because most dermatologists have difficulty identifying ectoparasitoses, such as those that arise within new or atypical conditions.