Pigeon tick bite: A neglected cause of idiopathic nocturnal anaphylaxis.

Anaphylaxis is a serious systemic allergic reaction with rapid onset and potentially life-threatening. We report in detail a case of severe nocturnal anaphylaxis due to pigeon tick bite showing the diagnostic value of the extract and the recombinant allergen in the diagnostic procedures (basophil activation test, IgE immunoblot, and experimental ImmunoCAP). Apart from the presented case, we describe that during the last 10 years, we have collected 28 cases of allergy to Argas reflexus from several European countries. We suspect that this allergy is underdiagnosed because of the lack of diagnostic reagents. Because of the growing number of pigeons in Middle and Southern Europe cities, some cases of idiopathic anaphylaxis could potentially be caused by A. reflexus in those countries. The identification of pigeon ticks as a trigger of anaphylaxis would greatly improve medical care and advice for these patients as the parasite can be exterminated by eradication measures to avoid further incidents.

Basophil activation can predict clinical sensitivity in patients after venom immunotherapy.

OBJECTIVE: At present, no reliable in vitro test is available to monitor the success of specific venom immunotherapy (VIT) in preventing insect venom anaphylaxis. We investigated usefulness of the basophil activation test (BAT) in predicting the outcome of sting challenge in bee venom-allergic patients after VIT. PATIENTS AND METHODS: Twenty-one patients with bee venom anaphylaxis at the end of VIT and 6 control participants were enrolled. BAT (flow-cytometric evaluation of allergen-induced expression of CD63), skin testing, and specific immunoglobulin (Ig) E determination were performed prior to sting challenge. RESULTS: Five of the 21 patients (23.8%) reacted to sting challenge. At a bee venom concentration of 100 ng/mL, the mean proportion of basophils expressing CD63 was 56% in reactors and 13.2% in nonreactors (P = .0321). Four of the 5 reactors had positive results and 14 of the 16 nonreactors had negative results. Thus, using 18.4% and 21.6% (receiver operating characteristic curve analysis) as the cutoff for expression of the CD63 marker, the positive and the negative predictive values were 67% and 93%, respectively, and specificity and sensitivity for BAT were 80% and 83%, respectively. However, at a concentration of 1000 ng/mL, no significant differences in basophil activation were observed between reactors and nonreactors. CONCLUSION: We found BAT to be a helpful tool in predicting the clinical sensitivity of bee venom-allergic patients after VIT (correlation between BAT at submaximal venom concentration and sting challenge).