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2006

'Scratch' the Confusion Away: Hopkins Researchers Develop New Quick Tool to Sort Out Insect Bites in Children

MEDIA CONTACT: Ekaterina Pesheva
EMAIL: epeshev1@jhmi.edu
PHONE: (410) 502-9433

June 27, 2006


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 Center 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 pediatricians and others to recognize 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 pediatricians recognize the problem early on,” says Raquel Hernandez, M.D., a third-year resident at the Children’s Center and lead author of the article, published in the July online edition of Pediatrics.  

Hernandez and co-author Bernard Cohen, M.D., head of dermatology at the Children’s Center, developed SCRATCH by examining a month’s worth of patient records from visits to the Children’s Center 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 pediatricians 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.BR>

S for Symmetry  

Erruptions 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 Clusters  

Lesions 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 Required  

Presence of pets in the household is not a criterion for diagnosis because a bite might occur outside of the home.

A for Age Specific  

The condition is most prevalent in children between the ages of 2 and 10. 

T for Target Lesions and Time  

Target-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 Confusion
 

Parents 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 Affected  

Unlike 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.



Founded in 1912 as the children's hospital of the Johns Hopkins Medicine, the Johns Hopkins Children's Center offers one of the most comprehensive pediatric medical programs in the country, with more than 92,000 patient visits and nearly 9,000 admissions each year. Johns Hopkins Children Center is consistently ranked among the top children's hospitals in the nation by U.S. News & World Report. It is Maryland's largest children’s hospital and the only state-designated Trauma Service and Burn Unit for pediatric patients. It has recognized Centers of Excellence in dozens of pediatric subspecialties, including allergy, cardiology, cystic fibrosis, gastroenterology, nephrology, neurology, neurosurgery, oncology, pulmonary, and transplant. For more information, visit www.hopkinschildrens.org.