What Does FPIES Stand For?
FPIES is Food Protein-Induced Enterocolitis Syndrome. It is commonly pronounced "F-Pies", as in "apple pies", though some physicians may refer to it as FIES (pronounced "fees", considering food-protein as one word). Enterocolitis is inflammation involving both the small intestine and the colon (large intestine).
What is FPIES?
FPIES is a non-IgE mediated immune reaction in the gastrointestinal system to one or more specific foods, commonly characterized by profuse vomiting and diarrhea. FPIES is presumed to be cell mediated. Poor growth may occur with continual ingestion. Upon removing the problem food(s), all FPIES symptoms subside. (Note: Having FPIES does not preclude one from having other allergies/intolerances with the food.) The most common FPIES triggers are cow's milk (dairy) and soy. However, any food can cause an FPIES reaction, even those not commonly considered allergens, such as rice, oat and barley.
A child with FPIES may experience what appears to be a severe stomach bug, but the "bug" only starts a couple hours after the offending food is given. Many FPIES parents have rushed their children to the ER, limp from extreme, repeated projectile vomiting, only to be told, "It's the stomach flu." However, the next time they feed their children the same solids, the dramatic symptoms return.
What Does IgE vs Cell Mediated Mean?
IgE stands for Immunoglobulin E. It is a type of antibody, formed to protect the body from infection, that functions in allergic reactions. IgE-mediated reactions are considered immediate hypersensitivity immune system reactions, while cell mediated reactions are considered delayed hypersensitivity. Antibodies are not involved in cell mediated reactions. For the purpose of understanding FPIES, you can disregard all you know about IgE-mediated reactions.
When Do FPIES Reactions Occur?
FPIES reactions often show up in the first weeks or months of life, or at an older age for the exclusively breastfed child. Reactions usually occur upon introducing first solid foods, such as infant cereals or formulas, which are typically made with dairy or soy. (Infant formulas are considered solids for FPIES purposes.) While a child may have allergies and intolerances to food proteins they are exposed to through breastmilk, FPIES reactions usually don't occur from breastmilk, regardless of the mother's diet. An FPIES reaction typically takes place when the child has directly ingested the trigger food(s).
What is a Typical FPIES Reaction?
As with all things, each child is different, and the range, severity and duration of symptoms may vary from reaction to reaction. Unlike traditional IgE-mediated allergies, FPIES reactions do not manifest with itching, hives, swelling, coughing or wheezing, etc. Symptoms typically only involve the gastrointestinal system, and other body organs are not involved. FPIES reactions almost always begin with delayed onset vomiting (usually two hours after ingestion, sometimes as late as eight hours after). Symptoms can range from mild (an increase in reflux and several days of runny stools) to life threatening (shock).
In severe cases, after repeatedly vomiting, children often begin vomiting bile. Commonly, diarrhea follows and can last up to several days. In the worst reactions (about 20% of the time), the child has such severe vomiting and diarrhea that s/he rapidly becomes seriously dehydrated and may go into shock.