Insect Bite Diagnostic Aid: S-C-R-A-T-C-H

(The above image is a linked image from the article by Hernandez and Cohen)

Hernandez and Cohen developed a diagnostic guidelines when they found that a majority of children with a final diagnosis of an insect-bite hypersensitivity reaction had undergone costly, unnecessary and extensive lab tests and skin biopsies before they were referred to Johns Hopkins Children's Center.

This set of principles (termed "SCRATCH") are intended to aid clinicians in making an early and accurate clinical diagnosis of insect bite:

S = Symmetry — Most patients with insect-bite hypersensitivity reactions present with symmetrical eruptions on the face, neck, arms, and legs, with sparing of the diaper area, palms, and soles of the feet.

C = Clusters — Lesions usually appear in a 'meal cluster,' sometimes described as 'breakfast, lunch, and dinner.

R = Rover Not Required — The diagnosis is not dependent on the presence of household pets. Exposure could come from periodic visits to a relative's house, for example.

A = Age-specific — The condition is most prevalent in children between the ages of two and 10.

T = Target Lesions/Time — Bull's-eye-rashes are typical of insect-bite reactions. The time refers to the chronic nature of the eruption and the need for patience and watchful waiting. Parents are advised to prevent secondary infections with appropriate use of nail and hand hygiene and moisturizers.

C = Confusion — Parents are often confused by the conflicting information they have been given, and the referring practitioner may find it hard to accept the diagnosis of an admittedly confusing condition.

H = Household — Unlike scabies or dermatitis, insect-bite reactions may affect only one household members who are hypersensitive

The FULL TEXT of the article by Hernandez and Cohen can be downloaded FREE in pdf format here.