Anaphylaxis to sheep's milk cheese in a child unaffected by cow's milk protein allergy

A 5-year-old atopic boy unaffected by cow's milk protein allergy experienced several anaphylactic reactions after eating food containing "pecorino" cheese made from sheep's milk. Prick-prick tests were strongly positive to sheep's buttermilk curd and 'pecorino' sheep's cheese, Skin prick tests to fresh sheep's milk and to goat's milk were also positive, whereas they were negative to all cow's milk proteins, to whole pasteurized cow's milk and to cheese made from cow's milk. Specific IgE antibodies were negative to all cow's milk proteins. Conclusion Sheep's milk and cheese derived from sheep's milk may cause severe allergic reactions in children affected and, as we report, in children not affected by cow's milk protein allergy.