[Argas reflexus, the pigeon tick. A case report]

The importance of this case, an episode of anaphylactic reaction for Argas reflexus, the pigeon tick, is due to the ever-increasing presence in urban areas of the pigeon. The knowledge of existence of this parasite and of his biological characteristics is essential to make a correct and timely diagnosis, to avoid the frequent relapse of symptoms, to take the necessary therapeutical and preventive measures.

Allergy to pigeon tick (Argas reflexus) in Upper Silesia, Poland

The pigeon tick Argas reflexus is avian ectoparasite that typically feeds on pigeons. When devoid of a natural host, the ticks can also attack humans. In Upper Silesia, southern Poland, people living in the vicinity of the birds' nesting sites are frequently bitten by A. reflexus. The bites can provoke serious allergic reactions, including fatal anaphylactic shock. In the present study, residents of 9 apartments invaded by pigeon ticks were invited to undergo medical examination, skin prick tests (SPT) and determination of specific IgE to A. reflexus. The test allergens were prepared of ticks collected on-site. Out of 18 residents living in the infested apartments, 15 accepted the invitation. In this group, 8 persons complained of tick-related health problems, positive SPT to A. reflexus were found in all of them, and specific IgE was detectable in 3 persons (range: 0.38-0.84 kUA/l; CAP class 1-2). Final clinical diagnoses were established of generalised urticaria with asthma in 1 person, generalised urticaria in another 1, and local allergic reactions to tick bites in the remaining 6. Among 7 symptom-free residents, all test results were negative. Besides the study group, the paper also describes the case of a person who developed hypersensitivity to A. reflexus as a child, after a few visits to an abandoned dovecote. 30 years later, positive SPT (++) and specific IgE (0.78 kUA/l; CAP class 2) were still present despite no further re-exposures. The article also discusses available pest control measures against A. reflexus.

Bites of the European pigeon tick (Argas reflexus): Risk of IgE-mediated sensitizations and anaphylactic reactions

BACKGROUND

Local and systemic reactions can occur after bites of Argas reflexus (Argas), a soft tick parasitizing pigeons.

OBJECTIVE

Risk assessment of IgE-mediated sensitizations and systemic reactions after Argas bites.

METHODS

Case histories, skin prick tests (SPTs) with a whole-body extract of Argas containing major allergen Arg r 1, and common inhalants and specific IgE measurements were obtained from 148 subjects who had had Argas bites and 20 volunteers as a control group.

RESULTS

Systemic reactions (urticaria, angioedema, dyspnea, cardiovascular dysregulation, unconsciousness) were reported in 12 of 148 (8%); 146 of 148 (99%) had local reactions. Atopy was found in 37 of 146 (25%) with local reactions and 3 of 12 (25%) with systemic reactions. SPT to Argas was positive in 24 of 148 (16%) with a high proportion of atopics 10 of 24 (42%); specific IgE to Argas was detectable in 12 of 135 (8% of 148) with moderate concordance to systemic reactions. No positive SPT or specific IgE results to Argas were obtained in the control group. Immunoblotting of 23 sera revealed an IgE-binding protein in 19 of 23 sera (82%) at 22 kd, indicating a major allergen of Argas.

CONCLUSION

Severe anaphylactic reactions were infrequently (approximately 8%) found after bites of the soft tick Argas reflexus. Atopy is a risk factor for skin sensitizations to Argas, but not for systemic reactions after bites by Argas. Using a whole-body extract of Argas, diagnosis through SPT and specific IgE is hampered by false-negative and irrelevant positive results, particularly in atopy.

IgE-mediated anaphylaxis caused by bites of the pigeon tick Argas reflexus: cloning and expression of the major allergen Arg r 1

BACKGROUND

Anaphylactic reactions caused by bites of the European pigeon tick Argas reflexus are repeatedly reported. This soft-backed tick is a parasite of wild pigeons colonizing urban buildings and houses. Occasionally the ticks can bite human beings, inducing anaphylactic reactions in sensitized patients.

OBJECTIVE

Our aim was to characterize the major allergen implicated in a series of anaphylactic reactions caused by Argas bites and to produce the allergen as recombinant protein for diagnostic purposes.

METHODS

Protein extracts were prepared from whole A reflexus bodies, and IgE immunoblots were performed with sera from 13 patients who had an anaphylactic reaction with pigeon tick bites. A cDNA expression library was constructed from whole ticks and screened with a polyclonal rabbit antiserum raised against the major allergen.

RESULTS

The cDNA coding for the dominant allergen Arg r 1 could be isolated. It encodes a protein belonging to the lipocalin family. Allergenicity of the recombinant Arg r 1 was confirmed by immunoblot, ELISA, and intradermal skin tests.

CONCLUSION

The dominant allergen of A reflexus has been isolated and the corresponding cDNA cloned. The recombinant protein, a lipocalin, was expressed in Escherichia coli and was shown to be immunoreactive in vitro and in vivo. Recombinant Arg r 1 was used as a diagnostic tool in a series of anaphylactic reactions caused by pigeon tick bites.

Anaphylactic shock to Argas reflexus bite

Anaphylaxis is a severe, life-threatening allergic reaction, affecting both children and adults. The occurrence of anaphylaxis is not as rare as generally believed (1.21% to 15.04% of the US population). Often the cause of this reaction remain unknown, mainly due to the difficulty in defining the outbreaking causes. Herein, we describe an interesting case of a patient, who developed an anaphylactic reaction after the bite of a pigeon tick. During the last 2 years, in wintertime, the patient often came to the emergency room for general rash and swelling, hypotension and tachycardia preceded by itching and general distress. Notably, the symptoms manifested themselves as night fell. In two particular occasions the patient reached the hospital in a state of shock. After another episode of general swelling, the patient was invited to examine her domestic environment. She brought us some parasites, collected at home, particularly on the bed. A morphological examination by entomologists proved these parasites to belong to Argas reflexus (Arg.r.), one of the 31 species of soft ticks. The presence of specific IgE to a protein secreted by the Arg.r. salivary glands was in favour of immediate-type systemic reaction, as supposed by the clinical history.

Allergy to Pigeon Tick (Argas reflexus): Demonstration of Specific IgE-Binding Components

BACKGROUND

The European tick, Argas reflexus, is an urban pest parasitizing urban pigeons and may cause a wide range of allergic reactions.

METHODS

Specific IgE to A. reflexus, SDS-PAGE and IgE immunoblotting, performed with tick extract, were carried out in the sera of 6 patients who reported allergic reactions after tick bite.

RESULTS

Specific IgE to A. reflexus (RAST class ranging from 1 to 3) were detected in the sera of 6 patients who reported allergic reactions (urticaria and angioedema in 2 and anaphylaxis in the other 4 patients) after tick bite. IgE reactivity to two bands of 22 and 40 kDa were identified in the patient sera.

CONCLUSIONS

Allergy to A. reflexus has to be considered in allergic patients living in buildings where pigeons have their nests. The powerful sensitizing property of tick allergen is underlined by the observation that none of our patients was atopic.