A Tissue Digestion Protocol for Measuring Sarcoptes scabiei (Astigmata: Sarcoptidae) Density in Skin Biopsies.

Sarcoptic mange is a parasitic skin disease caused by the burrowing mite Sarcoptes scabiei that affects a diversity of mammals, including humans, worldwide. In North America, the most commonly affected wildlife includes wild canids, such as coyotes and red foxes, and more recently American black bears in the Mid-Atlantic and Northeast United States. Currently, surveillance for sarcoptic mange in wildlife is syndromic, relying on detection of clinical signs and lesions, such as alopecia and crusting of skin. When possible, skin scrapes are used to identify the causative mite. While skin scrapes are a valuable diagnostic tool to identify mites, this approach has significant limitations when used for quantification of mite burden. To further investigate mite burden in cases of sarcoptic mange, 6-mm punch biopsies were collected from affected skin of red foxes (Vulpes vulpes Linnaeus [Carnivora: Canidae]), a species historically affected by sarcoptic mange, frequently with high mite burdens and severe skin disease, and validated on skin tissue from mange-affected American black bears (Ursus americanus Pallas [Carnivora: Ursidae]) and coyotes (Canis latrans Say [Carnivora: Canidae]). Biopsies were digested by incubating the tissue in potassium hydroxide (KOH) at 55°C. The greatest tissue clearance and lowest mite degradation resulted after 12 h of tissue digestion. The purpose of this manuscript is to describe a methodology for host tissue digestion and mite quantification in cases of sarcoptic mange. This method will provide a valuable surveillance and research tool to better understand sarcoptic mange in wild and domestic animals, with applications to a diversity of other ectoparasitic diseases.

Diagnosis and treatment of scabies: a practical guide.

Scabies is a common, highly pruritic infestation of the skin caused by Sarcoptes scabiei var. Hominis. It is a very contagious parasitosis with specific lesions, such as burrows, and nonspecific lesions, such as papules, vesicles and excoriations. The typical areas of the body it affects are finger webs, wrists, axillary folds, abdomen, buttocks, inframammary folds and, in men, the genitalia. It is characterized by intense nocturnal pruritus. Scabies is spread through close personal contact (relatives, sexual partners, schoolchildren, chronically ill patients and crowded communities). Definitive diagnosis is made when the scabies mites or their eggs or fecal pellets can be identified on a light microscope. New techniques for diagnosis include the use of the epiluminiscence microscopy. The most common topical treatments for scabies include lindane and permethrin. Permethrin provides a greater margin of tolerability because of its low inherent toxicity and low percutaneous absorption. Oral ivermectin is the most recently developed treatment for scabies. A single oral dose of ivermectin 200 microg/kg of bodyweight is a well-tolerated and very effective treatment. It is especially indicated in crusted scabies, scabies in immunocompromised hosts and infestations in crowded communities. It is also useful as a simple treatment in the prophylaxis of close contacts.

Ectoparasites as sexually transmitted diseases.

Although Sarcoptes scabii and Phthirus pubis infestations in humans are not always associated with the presence of other sexually transmitted diseases, usually they are. Therefore, patients presenting with scabies or P. pubis should be routinely tested for various sexually transmitted diseases. These very uncomfortable infestations are easily curable with proper therapy. Lindane 1% preparations effectively exterminate both vermin. We have not seen any resistant strains. Especially with P. pubis, all household contacts should be treated to avoid reinfestation.