Acute urticaria caused by pigeon ticks (Argas reflexus)

A 28-year-old man was admitted to our institute because of acute urticaria appearing a few hours earlier. The patient stated that during sleep he had been bitten by a large number of "insects," which had dropped from wooden ceiling beams under the roof of his room. The patient was living in the center of Milan in a very old house, where numerous pigeons had built their nests under the rooftop. The patient brought along with him some examples of these "insects," which were later classified as pigeon ticks (Argas reflexus) (Figs. 1,2). Dermatologic examination revealed the presence of numerous wheals and erythemato-papular lesions on the neck and trunk. These lesions were of different shapes and sizes, bright red in color, and with a small central ulceration corresponding to the tick bite. In addition, there were numerous excoriated lesions due to scratching; the patient in fact complained of very intense pruritus. The general physical examination was within normal limits. Laboratory examinations revealed only slight leukocytosis (9300 WBC/mm3). All other laboratory tests were negative; in particular, the assay for anti-Borrelia burgdorferi IgG and IgM was within normal ranges (< 1:256 and < 1:64, respectively). These results were confirmed on subsequent blood samples. Positive radioallergosorbent tests (RAST) to a somatic extract and to the saliva of the tick were observed. A diagnosis of acute urticaria caused by A. reflexus was made. The patient was treated with betamethasone (4 mg intravenously) and chlorpheniramine (10 mg intramuscularly), with resolution of the clinical picture within 3 days.