Examine other medical specialties for dermatologic answers

February 1, 2005

North Adelaide, Australia — In some selected Aboriginal communities in Australia's Northern Territory, up to 25 percent of adults and 50 percent of children may have scabies today — more than 100 years after the medical community claimed to master its diagnosis and cure, says Lachlan Warren, M.D., a dermatologist at Women's & Children's Hospital here.

North Adelaide, Australia - In some selected Aboriginal communities in Australia's Northern Territory, up to 25 percent of adults and 50 percent of children may have scabies today - more than 100 years after the medical community claimed to master its diagnosis and cure, says Lachlan Warren, M.D., a dermatologist at Women's & Children's Hospital here.

Noting the inadequacy of current treatments not only for scabies but for other common skin conditions such as seborrhoeic keratoses and atopic eczema, Dr. Warren encourages dermatologists to examine how new findings in other medical specialties may impact diagnostic and treatment paradigms for skin.

Underlying factors Scabies underlies up to 50 percent to 70 percent of aboriginal streptococcal skin infection and is associated with acute post-streptococcal glomerulonephritis and rheumatic heart disease, says Dr. Warren. In cases of crusted scabies, there are as many as 4,700 mites per gram of skin shed and harvested. Linked to immunodeficiency including trisomy 21 (Down syndrome), HIV (human immunodeficiency virus) and HTLV-1 (human t-cell leukemia virus-1), Dr. Warren says researchers are examining whether the high incidence of crusted scabies in some communities is due to reinfestation or recrudescence.

Dr. Warren is part of a team that last fall launched an experimental treatment and tracking program.

"We're attempting to treat entire communities and regions in Northern Australia," he explains. Initiated by the aboriginal communities, Dr. Warren says entire communities will receive topical or oral treatments, while at the same time researchers collect mite samples for analysis and DNA fingerprinting.

"Our goal is to reduce the high incidence of crusted scabies and to reduce the secondary problems such as bacterial skin infections," he says. "At the same time we will use DNA fingerprinting to follow the cycles and work out the epidemiology. We'll subsequently monitor these communities for scabies infections and measure the consequences of reducing the scabies population."

According to Dr. Warren, the Australian Department of Health is funding the three-year project. "This model has had some success in Central America, but there is the potential problem of mite resistance, so correct treatment needs to be clarified."

Defying tradition Nor do dermatologists need to look as far as Northern Australia for skin disorders that defy traditional treatments. Dr. Warren points to atopic eczema, which is on the rise worldwide. In Melbourne, studies report 30 percent of 1-year-olds suffering from the condition; in infants of Asian-born mothers, incidence jumps to 40 percent.

"In the 1980s, the assumptions were to promote a clean environment, avoid pets, use synthetic bedding and prolong breastfeeding - much of which has not been proved correct," says Dr. Warren.

For example, a "clean environment" in early life promotes, rather than inhibits, allergy and eczema.

Breastfeeding exclusively beyond the age of 4 months, on the other hand, does reduce early eczema - but may also increase the likelihood of adult asthma and adult allergen sensitization.

"For some families, infant atopic eczema is a severe burden that leads to the adoption of questionable, yet costly, practices," Dr. Warren says. "As dermatologists recognize the potential role of food allergies and environmental manipulations, we're seeing improvement both in the patients' symptoms and in the families' emotional health."

Specific advancements in DNA fingerprinting and immune system research aside, the overriding message to dermatologists is to constantly re-examine assumptions on the basis of old and new evidence.

"Our existing assumptions aren't necessarily incorrect," he says, "but we need to constantly assess new evidence and keep assumptions in perspective with current knowledge.