I knew my middle child was allergic to egg since she was 6 months. She was chewing on my sandwich in a café, and developed a rash round her mouth. I thought at first it was the roughness of the bread, but quickly realised it was the mayonnaise she was reacting to.
I didn’t worry too much about it, but over the course of the next few months the reaction got worse when she ate food containing egg. So off we went to the immunologist who did skin prick testing, and we found out she was allergic to eggs and dairy also. She was breastfed, and had never been exposed to dairy at this point in time, so I hadn’t realised. Luckily she grew out of the dairy allergy at 15 months.
After our trip to the immunologist, she was on a strictly no egg diet, based on the severity of her reaction to the skin prick test. Unfortunately, when she was 21 months, she was accidently given food containing egg. The amount she ingested would have been much less than 1g, but this was enough to send her into anaphylactic shock. In little children, anaphylaxis looks very different to with older kids. In her case, there was no puffiness or swelling. She merely fell to the floor, semi-conscious, pale and floppy, and struggling to breathe. She fully recovered, after an afternoon in emergency, but after that, we were given an epi-pen. This went everywhere she went for the next four years.
So what is a skin prick test? A skin prick test is the first port of call in diagnosing a Type 1 (IgE-mediated) allergic reaction. A grid is draw on the arm, and each box of the grid in given a number. Small amounts of the allergen are put on the skin, one allergen to each box, and the skin is scratched with a blade. This allows the allergen to enter the skin. When the person is allergic, histamine and other chemicals are released by the body, and a wheal develops over the course of the next 15 minutes. The wheal is measured, and the result is considered positive (i.e the person is allergic) if the wheal is over a certain size (3mm diameter).
Children will often grow out of allergies, especially egg. When the child is anaphylactic however, the chance of them growing out of it reduces. Over the next few years, I gave my daughter lots of fermented foods (especially kefir) and probiotics to help her develop a healthy microbiome. Due to congenital heart disease, she had several open heart surgeries as an infant, followed by megadoses of antibiotics. This would have destroyed the healthy flora of her gut, making her more susceptible to allergies.
When she as nearly four she had a “food challenge” as the children’s hospital. They fed her 0.6g of egg. She got hives and vomited.
Then came a breakthrough. A month later we went back for a baked egg challenge, where she had to eat half a muffin over the course of the day, and she passed! Over the next 12 months, we had to give her baked egg at least once a week to desensitize her. Baked egg means there are 2 eggs in about 500g, which is cooked for 20 minutes at 180˚C. As we don’t eat cakes or baked treats, I had to get a bit creative in how I got this baked egg into her!
So what is a food challenge? A food challenge is how to positively confirm a food allergy. It happens in a hospital setting, in case the child has a serious adverse reaction. It is useful if it is suspected that a child may have outgrown an allergy, for instance if a skin prick test reaction has reduced over time. A very small amount of the allergenic food is given to the child, and the amount is increased over time. About every 20-30 minutes more of the food is given. This in itself can be quite challenging – if you have spent years telling your child to not eat a food, and then all of a sudden, you are begging them to eat it! If the child makes it all the way to the maximum dose without a reaction, they have passed the challenge!
This week, we went back and repeated the food challenge for egg, and she passed! Early indications were good, when they did the skin prick test there was a negligible reaction. Now she needs to eat ¼ of a well cooked egg every day for a week, and then ½ well cooked egg once or twice a week for 6 months. All being well after that, we can start to have the egg a little well cooked, until ultimately she will be able to eat mayonnaise. What an egg-cellent result!