In patients infected with scabies, clinical examination limited to the hands, feet and thighs may be sufficient, if there is no itching elsewhere.
Scabies is a very contagious skin infection that gives very severe itching and some skin lesions. It is caused by a microscopic skin parasite Sarcoptes scabiei hominis. For years, the diagnosis of scabies has relied on a tedious and intrusive whole-body clinical examination.
Researchers from the London School of Hygiene & Tropical Medicine have just demonstrated that simple examination of the hands, feet and lower legs can detect more than 90% of cases of scabies, regardless of their severity. This study is published in PLOS Neglected Tropical Diseases.
A clinical diagnosis
The diagnosis of scabies is primarily clinical. The doctor will look for signs and dermatological lesions characteristic of the disease. He usually does not need additional examinations.
Scabies should be mentioned in the face of any persistent itching (pruritus), most often located on the wrists, and more intense at night (“nocturnal recrudescence”), especially in the event of multiple infections (family, sexual partner, community). ). The diagnosis of scabies in “clean people” is often difficult because of the rarity of skin lesions and it must be considered in the face of persistent diffuse pruritus.
For certain atypical forms where the diagnosis is not easy, it is possible to take a skin sample in search of the parasite. Using a curette, the doctor will scrape the pearly blisters to collect as many scales as possible. These skin fragments will then be examined under a microscope by the biologist in order to directly visualize the parasite or its eggs.
An analysis of 3 surveys
In the new work, Michael Marks from the London School of Hygiene & Tropical Medicine and colleagues analyzed data from three recent large population-based scabies surveys in the Solomon Islands and Fiji. The scabies examinations in the patients examined included nine regions of the body. If patients reported itching elsewhere in the groin, buttocks, or breasts, those areas were also examined.
Examination of exposed skin is sufficient
The team concluded that examining exposed areas of the body (hands, feet and lower legs) has a scabies detection sensitivity of nearly 90% compared to a full body examination. More restrictive examinations, limited to the hands for example, reduce the sensitivity too much, which is then only 51.2%.
This study is of course interesting for large screening studies for the disease in developing countries, but it also provides valuable data for the simplified diagnosis of scabies which can be applied in outpatient clinics, because these 3 areas are already not always examined. If patients report itching elsewhere, the examination will of course have to be extended.
.
