‘SCRATCH’ The Confusion Away: New Tool to Sort Out Insect Bites in Children

Children afflicted with insect-bite rashes are often misdiagnosed or referred for extensive and costly tests, but a new, easy-to-remember set of guidelines developed at the Johns Hopkins Children’s Centre should help.

Called SCRATCH, the letters form a memorable acronym for symmetry, cluster, rover, age, target/time, confused, household). It is a guide to the symptoms and features that help paediatricians and others to recognise the source of a rash.Insect-bite skin rashes mimic the symptoms of a variety of conditions, ranging from fungal infections, scabies, allergies and environmental contacts, to HIV-associated dermatoses. Reactions to a bite are often delayed, making it difficult to trace exposure.”SCRATCH could spare many children and their parents from going through invasive-not to mention expensive-procedures if paediatricians recognise the problem early on,” says Raquel Hernandez, M.D., a third-year resident at the Children’s Centre and lead author of the article, published in the July online edition of Paediatrics.Hernandez and co-author Bernard Cohen, M.D., head of dermatology at the Children’s Centre, developed SCRATCH by examining a month’s worth of patient records from visits to the Children’s Centre dermatology clinic. They found that the majority of children who were eventually diagnosed with an insect-bite rash had undergone extensive lab tests and skin biopsies before they were referred to Hopkins.The most common misdiagnosis was scabies, a skin infection caused by a parasite that produces red, itchy lesions. Many of the children were treated repeatedly for scabies.”These guidelines are really intended to make paediatricians consider insect-bite hypersensitivity as a diagnosis and think twice before referring a child for a skin biopsy or another invasive procedure,” Cohen says. Using the tool is straightforward, Cohen adds. If the rash fits the SCRATCH criteria, it’s likely bug-borne.S for SymmetryErruptions are usually symmetric and appear on exposed parts of the body, such as face, neck, arms, legs. Younger children may have rashes on their scalps. Diaper areas, palms and soles are not affected. The trunk is rarely affected. By contrast, scabies causes rashes on palms, soles and between toes and fingers.C for ClustersLesions appear in “meal clusters”, described as breakfast, lunch and dinner. The linear or triangular clusters are typical of bedbug bites, but also appear in bites caused by fleas.R for Rover Not RequiredPresence of pets in the household is not a criterion for diagnosis because a bite might occur outside of the home.A for Age SpecificThe condition is most prevalent in children between the ages of 2 and 10.T for Target Lesions and TimeTarget-shaped lesions – named so for their resemblance to the bull’s eye on a target – are typical of insect-bite hypersensitivity. Time indicates the chronic/recurrent nature of the eruptions. Many patients may have delayed reactions and may not experience flareups until months or years after the intial exposure. Most children develop full immunity by age 10 and no longer have recurrent rashes.C for ConfusionParents often express confusion and disbelief at the suggestion that there might be fleas or bedbugs in their homes. “One of the primary criteria is that if the parents don’t believe me, I am probably right,” Cohen says.H for Household with Single Family Member AffectedUnlike conditions that have similar symptoms, such as scabies and atopic dermatitis, insect-bite rashes often appear in a single member in a family.”Common sense might tell us that fleas and mosquitoes would affect other members of the family, but we must keep in mind that these rashes develop in children who have hypersensitivity that others do not have,” Hernandez said.(Source: Paediatrics: Johns Hopkins Medicine: June 2006).