Yes, parasites. Just the word makes most of us shiver. Some people will even refuse to discuss or think about them. While we are more comfortable with parasites existing in animals, such as tapeworms dogs and cats, the fact is that most people probably have parasites too--even in the United States, Europe and other developed areas of the world. Doctors such as the well known TV personality Dr. Oz; Dr. Ross Anderson, a parasitic infection specialist and author; Dr. Peter Wina, Chief of Patho-Biology in the Walter Reed Army Institute of Research; and Dr. Frank Nova, Chief of the Laboratory for Parasitic Diseases of the National Institute of Health have all been quoted making statements that generally indicate as many as 85% to 95% of adults probably have parasites.
According to the USDA, “Young children, pregnant women, older adults, and persons with weakened immune systems,” are highly susceptible to parasites for several reasons. First, because the immune systems are weaker than most adults the parasite isn’t eliminated easily. Second, children are often on the ground and putting things into their mouths that may not be clean, specifically things that may have come into contact with animal or human feces. Third, children may accidentally swallow pool water that is contaminated since many parasites can live for several days in chlorinated water. Fourth, young children in day care can easily contract parasites from other children through shared diaper changing facilities. Fifth, eating raw, unwashed fruits and vegetables or eating undercooked meats can deliver parasites directly into human bodies. 
But how can parasites play a part in allergies, especially food allergies? According to Dr. Leo Galland, “One of the most common effects of intestinal parasites is food allergy. I looked at the effects of parasitic infection among patients in my medical practice. For people with multiple food allergies who were found to have intestinal parasites, treatment of the parasitic infection produced a dramatic reduction in food allergy in about half the cases. It's my belief that anyone with food intolerance or allergy should be tested for intestinal parasites…Parasites may cause allergic or autoimmune disorders in two ways. First, the inflammation caused by an intestinal infection can cause an increase in the permeability of the small intestine, a phenomenon known colloquially as ‘leaky gut’…Second, over two-thirds of your body's immune system is located in the wall of the small intestine. The immune cells (called lymphocytes) leave the intestine and travel all over your body. When activated by a parasitic infection, they can carry the inflammatory message to your joints, your skin, your eyes, and your lungs.” 
In summary, parasites can weaken the immune system and cause overreactions to otherwise harmless substances such as food allergens of soy, wheat, egg, dairy, peanuts, tree nuts, fish and shell fish. If a parent thinks that parasites might be a contributing factor to their child’s food allergies, then that parent could locate a doctor who understands and can treat a child for parasites. It may take several phone calls or visits to find a doctor that is educated in this area by being able to explain the appropriate tests and medications to rid the child’s body of parasites.
 USDA’s Foodborne Illness & Diseaser, “Parasites and Foodborne Illness,” May, 24 2011 http://www.fsis.usda.gov/factsheets/parasites_and_foodborne_illness/index.asp
 Galland, M.D., Leo, “What’s Living in Your Digestive System?”, Huffington Post, March 2, 2011 http://www.huffingtonpost.com/leo-galland-md/stomach-parasites_b_828565.html