Thank you for your inquiry.
Unfortunately, I am not going to be able to give you a definitive answer. As you have implied in your inquiry, the only way to determine if your patient’s allergic episodes are due to storage mite would be to obtain the flour, investigate it for the presence of mites, and demonstrate IgE-mediated sensitivity to storage mite extract. Without the flour, of course, you will not be able to determine if mite was present.
Although the degree of cross-reactivity between storage mite and house dust mite can be highly variable, with some studies showing little cross-reactivity (1) and other studies showing cross-reactivity not uncommon (2) it would at least be of interest to test with house dust mite.
ImmunoCAPS are available for numerous storage mites. A detailed discussion of each of these mites and their potential cross-reactivity with house dust mite is available on the Thermo/Phadia website. For your convenience, I have copied below the link to this website which lists each storage mite available for ImmunoCAP testing and the potential cross-reactivity between each mite and house dust mite. In addition, it discusses the reported clinical reactions to each variety. You can order ImmunoCAPS to each one of these which would be salient to your case.
In the meantime, I would of course consider working him up for other possible causes of anaphylaxis, remembering that in adults, in as many as 60% of patients no etiology can be found (3).
In summary, unfortunately, there is no definitive way at this point to determine whether your patient had an anaphylactic reaction to storage mite. However, in vitro tests are available to detect specific IgE against many storage mites at the website mentioned above. You should at least pursue these tests, and also explore other causes as well.
Reference Number 2 mentioned above is a well-written review of this topic which may help give you a better perspective on the evaluation of your patient.
Thank you again for your inquiry and we hope this response is helpful to you.
1. Arlian LG, et al. Cross-reactivity between storage and dust mites and between mites and shrimp. Exp Appl Acarol 2009; 47(2):159-72.
2. Sanchez-Borges M, et al. An update on oral anaphylaxis from mite ingestion. Ann Allergy Asthma Immunol 2005; 94(2):216-221.
3. Webb L and Lieberman P. Anaphylaxis: A Review of 601 Cases. Annals of Allergy, Asthma, and Immunology, July 2006; 97(1):39-43.
Phil Lieberman, M.D.