Scabies Infestation on Darker Skin: Diagnosis and Management

00:00 We spoke about complications of scabies.

00:02 Now we're going to talk about the diagnosis.

00:04 How do we diagnose scabies? So it's a clinical diagnosis.

00:09 However use of dermoscopy is quite useful.

00:13 And it's easy to diagnose scabies using dermoscopy.

00:17 And this is what one sees on Dermoscopy.

00:19 You can see the nice linear line of the white patch.

00:23 And that shows the burrow where the female mite gets, creates and gets under.

00:30 And right at the end of the white serpiginous line, you can actually see the mite at the end of the burrow.

00:39 So we can also use skin scrapes.

00:42 Scrapes. And this involves direct visualization of mites, which may be seen on preparation as well as the eggs or feces on microscopy.

00:53 And this picture shows a lovely preparation showing the larva stages of mites within the skin. We can also use the burrow ink test, where you get the classical zig-zag lines in the areas where the ink is chased into the burrow of the scabetic mite .

01:15 An adhesive tape test can also be used.

01:18 So here strips of tape are applied to areas suspected of being burrows and then rapidly pulled off. These are then applied to a microscope slide and examined under the microscope. Skin biopsy is rarely required or needed in patients with scabies because it's usually a clinical diagnosis.

01:39 However, if you have to do a skin biopsy, you may see the mites in the epidermis, as you can see on that histology slide.

01:52 The differential diagnosis of scabies includes atopic dermatitis, contact dermatitis, psoriasis, and this is how we treat patients with scabies. There's general measures, including bedding and clothing which should be washed. This also needs to be dried in direct sunlight because direct sunlight kills the mite. Some of the items that can not be washed should be sealed in a plastic bag for ten days, because that will suffocate the mite.

02:27 Soft furnishings should also be vacuumed and nails should be clipped and subungual debris cleared because when you scratch, you may get the mite remaining under your nail plate. Topical therapy includes 5% permethrin, which can be in a cream or lotion base.

02:47 This has to be applied overnight to the entire body surface from head to toe.

02:52 All family members and close contacts have to be treated simultaneously, even if they do not have clinical signs.

03:01 If you do not do this, your treatment of scabies is not going to be adequate, so the treatment can be repeated after 7 to 10 days.

03:12 The alternatives are the use of benzyl benzoate or sulfur 5% compounded .

03:21 Systemic therapy includes the use of ivermectin, and this is an option in cases of topical failure or inability to comply with topical therapy, and this is used as 200mg/kg and repeated in a week to two weeks.

03:39 It's good for treating large-scale outbreaks, particularly in nursing homes.

03:45 It's not a first-line treatment for pregnant individuals and children weighing less than 15kg. So, if there is unbearable pruritis, systemic antihistamines can be recommended. Please warn patients that pruritis may persist long after the treatment. So if a patient has pruritis, it doesn't mean that the disease is still active.