The story starts as any other we might cover: A 43 year-old woman in Japan is busy cooking a traditional okonomiyaki pancake for her family. She takes a few bites and breaks out in a rash, develops abdominal pain, starts wheezing, and struggles to breathe.
You would think this was a case of anaphylaxis triggered by a food allergy. You would be wrong.
She is rushed to the hospital where she tells doctors she made the pancake with flour stored for a year in an open bag in an ‘underground storage unit’.
Allergy tests confirmed the woman was not allergic to any of the ingredients in the pancake which included egg, yam, pork, prawns and squid, and her relatives that ate the same meal were fine.
The case write-up, submitted by Dr Katsunori Masaki of the department of internal medicine at Saiseikai Utsunomiya Hospital, reveals the cause: Upon analysis of a sample of the flour, it was determined there were up to 4,500 dust mites of the Dermatophagoides farinae variety and 11 of the microscopic mite species Chelacaropsis moorei per gram. There are 28 grams in an ounce.
In rare cases, consuming large quantities of the microscopic bugs can cause oral mite anaphylaxis, sometimes a hidden cause of severe reactions that is often overlooked. The woman, who suffered from hay fever, was also confirmed to have an allergy to dust mites.
Here is a closeup view of the flour under a microscope provided by Dr Masaki. WARNING: Not for the faint of heart!
Dust mites are more likely to contaminate flour in tropical and subtropical areas due to high temperatures and humidity, and contaminated flour may look normal: white and dry. Beware how you store your cooking ingredients!