TORONTO - Researchers in Chicago who work on mice have come up with a new way to mimic the symptoms of a person having a reaction to peanuts.

It means they have a new tool to help them better understand causes of food allergies and find new ways to treat and prevent them, said experts at the U.S. National Institute of Allergy and Infectious Diseases, which funded the research.

"The most significant obstacle to developing an animal model of food allergy is that animals are not normally allergic to food," said a news release issued Monday.

"Scientists must add a strong immune stimulant to foods to elicit a reaction in animals that resembles food allergy in humans."

Useful animal models have been developed only in the last few years, the statement said, and such animal models have until now used cholera toxin as the immune stimulant.

The research team, led by Paul Bryce of the Feinberg School of Medicine at Northwestern University, instead fed mice a mixture of whole peanut extract and a toxin from the bacteria Staphylococcus aureus, called staphylococcal enterotoxin B to simulate the human anaphylactic reaction to peanuts in mice.

"Persistent S. aureus colonization is commonly found on the skin of people with eczema and in the nasal cavities of people with sinusitis," Bryce said.

"The history between S. aureus and allergic diseases led us to use staphylococcal toxins to stimulate food allergy in animals."

The mixture caused symptoms in mice that closely resemble those found in human anaphylaxis, including swelling around the eyes and mouth, reduced movement and significant problems breathing.

The findings appear in the January issue of the Journal of Allergy and Clinical Immunology.

Peanut allergy is one of the food allergies most often associated with life-threatening reactions, and results in up to 100 deaths in the United States each year.

On its website, Anaphylaxis Canada says a conservative estimate is that two per cent of the Canadian population -- approximately 600,000 Canadians -- may be affected by potentially life-threatening allergies.

Allergic reactions to food can range from mild hives to vomiting to difficulty breathing to anaphylaxis, the most severe reaction.