ALLERGIC REACTIONS FROM INSECT BITES To the Editor:—A 54-year-old woman with no past medical history was sleeping outdoors and had a witnessed Triatoma envenomation on her left calf. She reported a mild hypersensitivity reaction to a previous Triatoma bite. She felt pruritus at the site and shortness of breath immediately. Bug identification was con- firmed by the emergency department (ED) staff. On presentation to the ED (30 minutes after envenomation), she was comatose. Her systolic blood pressure was 60 mm/Hg, heart rate was 89 beats/ min, respiratory rate was less than 6 breaths/min, and rectal tem- perature was 99.1°F. Her pupils were 6 millimeters and unreactive. Pulmonary examination revealed wheezing and rales throughout all fields. Diffuse urticaria was noted. No movement or response to stimuli was noted. Her neck, cardiovascular, abdominal examina- tion was unremarkable. Cranial computerized tomography of the brain was normal. Electrocardiogram revealed 1 mm ST depressions in lead V6 and I. A urine EMIT (Beckman Coulter) drug screen for amphet- amine, barbiturates, cocaine, ethanol, opiate, propoxyphene, tricy- clic, and cannabinoids was negative. Despite intubation and ACLS protocols, she was prounced dead 3 hours after envenomation. The Triatoma species, also known as the kissing bug or the cone-nosed bug, are known for being the vectors of Trypanosoma cruzi, the cause of Chagas’ disease. While Chagas’ disease is rare in the United States, the vectors are endemic from New Jersey and on southwards towards California. There are at least 10 Triatoma species, with T protracta and T rubida being the most commonly reported causes of allergic reactions. The Western/Southwestern United States report the most common allergic reactions. 1,2 Triatoma bugs often live near the nests or caves of their hosts, which include the wood rats, bats, and other small to medium- sized mammals. The bugs are attracted to human dwellings by the light at night. Thus, nearly all Triatoma bites occur nocturnally while the human host is asleep. The bites usually take place on the exposed areas of human skin, such as the arms, face, shoulders, and neck. The bugs feed on the blood of their hosts, and the feedings often last approximately 15 minutes. As the bite itself is painless, the host usually does not awaken during the feedings. Most humans experience no reactions to the Triatoma bite. Allergic reactions are rare, but have been reported since 1894. 3 Typically, as the bite itself is painless, the host will often awaken at night with severe pruritus secondary to the bite. The most common reaction after an envenomation is an erythematous, urti- carial placque that measures 2 to 3 centimeters. The plaque itself can extend up to fifteen centimeters if there were multiple bites in the same area. Scratching at the site worsens the urticaria. The lesions may also consist of small vesicles, hemorrhagic bullae, cellultitis, and/or edema. 1,2 Anaphylaxis reactions to the Triatoma bite, such as described in our patient, are rare. Cutaneous lesions include urticaria, angio- edema, flushing, and pruritus. Gastointestinal symptoms include nausea, vomiting, diarrhea, and abdominal cramps. Genitourinary symptoms include vaginal bleeding. Respiratory symptoms in- clude dypsnea, wheezing, and laryngeal edema. Syncope, hypo- tension, and coma have also been reported. 1-3 To our knowledge, we are reporting the first death from a Triatoma bite despite appropriate recussitative measures. ED management of Triatoma reactions depends on the severity. Topical steroids may be used for localized reactions, especially if itching is severe. Treatment of anaphylaxis includes quick and close management of the patient’s airway, breathing, and circula- tion. Decompensation may be very rapid as shown in our patient. Antihistamines and epinephrine should be administered immedi- ately. There is no “antivenom” for Triatoma bites in an emergent setting. Immunotherapy has been successful in preventing future anaphylaxis though it is not yet widely available. 3 Physicians need to be aware and suspicious of Triatoma bites in order to appropriately advise their patients. Prevention is key in management of Triatoma allergy and anaphylaxis. FRANK LO VECCHIO, DO, MPH Banner-Good Samaritan Regional Poison Center Maricopa Medical Center Department of Emergency Medicine THANH VAN TRAN, MD Maricopa Medical Center Department of Emergency Medicine Phoenix, AZ References 1. Lynch P, Pinnas J: “Kissing Bug” bites: Triatoma species as an important cause of insect bites in the Southwest. Cutis 1978;22(5): 585-591 2. Moffitt J, Venarkse D, Goddard J, et al: Allergic reactions to Triatoma bites. Ann Allergy, Asthma, Immunol 2003;91(2):122-128 3. Rohr A, Marshall N, Saxon A. Successful immunotherapy for Triatoma protracta-induced anaphylaxis. J Allergy Clinical Immunol 1984;73(3):369-375 4. Wolf A: Sensitivity to Triatoma bite. Ann Allergy 1969;27(6): 271-273 © 2004 Elsevier Inc. All rights reserved. 0735-6757/04/2207-0035$30.00/0 doi:10.1016/j.ajem.2004.09.020 631 CORRESPONDENCE