Q:

7/22/2013
I have a patient who has had 2 systemic reactions to the bite of a kissing bug (Triatoma Protracta). Is anyone doing research on this insect as I do not know of an extract to test with, rast test, or treatment option other than an Epipen. If there is research ongoing and this person could participate in some way, I would be glad to be of assistance as we do research in this office. Thanks.

A:

Thank you for your inquiry.

There is, to my knowledge, no commercially available test for IgE anti-triatoma. However, both Mayo Clinic Laboratory and Quest Laboratory offer an IgG ELISA to detect an immune response to triatoma. Although, of course, this test would not be useful to detect any “allergic” sensitization, it would be helpful to document that your patient has at least been bitten and developed an immune response to the bug.

At this time, I am not aware of any treatment other than epinephrine for the acute episode and attempts to rid the home environment of the bug. There have been successful reports (see abstract copied below by Rohr, Saxon, et al.) of desensitization to triatoma venom, but since, at least to my knowledge and based upon a search, no venom is available for testing or treatment (1), the issue remains moot at this time.

Parenthetically, there is an excellent fairly recent review of triatoma allergy which is available to you at no charge online. The abstract is also copied below (Klotz, et al.).

However, since I was unable to find any ongoing research protocol for venom available for testing or treatment, I am going to ask Dr. Jacob Pinnas, who has published extensively in this area, to respond to your inquiry as well. When I hear from Dr. Pinnas, I will forward his response to you.

Thank you again for your inquiry.

J Allergy Clin Immunol. 1984 Mar;73(3):369-75.
Successful immunotherapy for Triatoma protracta-induced anaphylaxis.
Rohr AS, Marshall NA, Saxon A.
Abstract
A successful program of immunotherapy for Triatoma protracta-induced anaphylaxis was developed. This program included a new passive extract-antigen preparation standardized by RAST inhibition. This antigen facilitated the development of a reliable skin test protocol for in vivo diagnosis of Triatoma protracta allergy. Five patients with T. protracta-induced anaphylaxis underwent a rapidly increasing dosage schedule of immunotherapy. The IgE- and IgG-antibody responses during immunotherapy were followed with solid-phase RIA. Protection against anaphylaxis was confirmed in all patients with a "bite challenge" by T. protracta. This is the first report of completely successful T. protracta immunotherapy.

Clin Infect Dis. 2010 Jun 15;50(12):1629-34. doi: 10.1086/652769.
"Kissing bugs": potential disease vectors and cause of anaphylaxis.
Klotz JH, Dorn PL, Logan JL, Stevens L, Pinnas JL, Schmidt JO, Klotz SA.
Source
Department of Entomology, University of California, Riverside, CA, USA.
Abstract
Physicians in the United States should familiarize themselves with "kissing bugs" endemic to their area of practice and appreciate the medical implications of their bites. Bite victims often seek advice from physicians about allergic reactions as well as the risk of contracting Chagas disease. Physicians are generally knowledgeable about the role of kissing bugs in the transmission of Trypanosoma cruzi in Latin America. However, they may be unaware of (1) severe allergic reactions to kissing bug salivary antigens, (2) the widespread occurrence of T. cruzi amongst vertebrate hosts of kissing bugs, and (3) the incidence of T. cruzi among kissing bugs (T. cruzi may infect >50% of sampled bugs). Despite the potential for Chagas disease transmission, the major concern regarding kissing bugs in the United States is anaphylactic reactions to their bites resulting in frequent emergency department visits, especially in areas of endemicity in the Southwest.

Reference:
1. Ann Allergy Asthma Immunol. 2003;91:122–128.

Sincerely,
Phil Lieberman, M.D.

We received a response from Dr. Jacob Pinnas. Thank you again for your inquiry and we hope this response is helpful to you.

Sincerely,
Phil Lieberman, M.D.

Response from Dr. Jacob Pinnas:
I do not believe there is any antigen available at this time for treatment.

The predominant species in our area is Triatoma rubida, whereas in California it is Triatoma protracta, and these did not cross react. Do we know the area and species involved in this case?

The “venom” we used was saliva or salivary gland extract, but at UCLA it was suspended in hemolymph which can be sensitizing. I am no longer rearing the insects or preparing extracts for treatment. However, there is a group in Tucson studying the insect but it has not been involved in treatment. They are working on an ELISA that may be available for research purposes. I may be able to facilitate arrangements for in vitro testing if interested.

EpiPen is usually prescribed but may not prevent death in someone at high risk.

It is sometimes advisable for such patients to move to a lower risk area, such as an urban part of town rather than foothills, or another city or state where the insect is not found.

Best regards,
Jacob Pinnas, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology