Allergic reaction. Lice infected skin with heterogeneous proteins into the skin, resulting in localized allergic reactions, clinical manifestations of severe itching of the skin, patients often scratching can lead to localized skin. Shrimp lice, also known as the crow shrimp or fog shrimp, body length is only a few millimeters in size, this low price, even the name of the lowly shrimp lice.