Acne Picture Rosacea
Scabies, also known as the itch, is a contagious ectoparasite skin infection characterized by superficial burrows and intense pruritus (itching). It is caused by the mite Sarcoptes scabiei. The word scabies itself is derived from the Latin word for "scratch" (scabere). Other names for the condition include Mite, Itch Mite, Mange, Crusted Scabies, Norwegian Scabies, Sarcoptes scabiei, or The Seven-Year Itch.
Signs and Symptoms
The characteristic symptoms of scabies infection include superficial burrows, intense pruritus (itching), a generalized rash and secondary infection. Acropustulosis, or blisters and pustules on the palms and soles of the feet, are characteristic symptoms of scabies in infants.
S-shaped tracks in the skin, and are often accompanied by small, insect-type bites called nodules that may look like pimples . These burrows and nodules are often located in the crevasses of the body, such as between fingers, toes, buttocks, elbows, waist area, genital area, and under the breasts in women .
The intense itching and rash characteristic of scabies infection is caused by an allergic reaction of the body to the burrowing of the microscopic scabies mites. The rash can be found over much of the body; the associated itching is often most prevalent at night .
Secondary infection is often due to impetigo, a type of bacterial skin infection, after scratching. Cellulitis may also occur, resulting in localized swelling, redness and fever (DermNet).
In immuno-compromised, malnourished, elderly or institutionalized individuals, infestation can cause a more severe form of scabies known as crusted scabies or Norwegian scabies. This syndrome is characterized by a scaly rash, slight itching and thickened crusts of skin containing thousands of mites. Norwegian scabies is the form of scabies that is hardest to treat.
In individuals never before exposed to scabies, the onset of clinical signs and symptoms is 4-6 weeks after infestation, some people may not realize that they have it for years; in previously exposed individuals, onset can be as soon as 1-4 days after infestation.
Compromised immune systems
People with compromised immune systems, such as HIV, cancer or transplant patients may be susceptible to crusted or Norwegian scabies. In this case the scabies go unregulated by cytotoxic cells and spread over the whole body, except the face. These cases require additional treatment options for resolution. Ivermectin is a single oral treatment of choice in these patients combined with any other topical treatment.
Gallery of scabies infections
Evolution of infection
Cause
Main article: Sarcoptes scabieiScabies is highly contagious and can be spread by scratching, picking up the mites under the fingernails and simply touching another person's skin. They can also be spread onto other objects like keyboards, toilets, clothing, towels, bedding, furniture, and anything else that the mite may be rubbed off onto, especially if a person is heavily infested. However, the parasite tends to die if outside a human body for more than 72 hours. Scabies is caused by the mite Sarcoptes scabiei, variety hominis, as shown by the Italian biologist Diacinto Cestoni in the 18th century. It produces intense, itchy skin rashes when the impregnated female tunnels into the stratum corneum of the skin and deposits eggs in the burrow. The larvae, which hatch in 3β10 days, move about on the skin, molt into a "nymphal" stage, and then mature into adult mites. The adult mites live 3β4 weeks in the host's skin.
The action of the mites moving within the skin and on the skin itself produces an intense itch which may resemble an allergic reaction in appearance. The presence of the eggs produces a massive allergic response which, in turn, produces more itching.
Scabies can be transmitted readily throughout an entire household, by skin-to-skin contact with an infected person (e.g. bed partners, schoolmates, daycare). It can be spread by clothing, bedding, or towels. Washing clothing in very hot water and dry on high heat will help prevent the transmission. Alternatively, permethrin sprays can be used for items that cannot be laundered.
The symptoms of itching and rash are caused by an allergic reaction that the human body develops over time to the mites and their by-products under the skin. As such, there is usually a 2-6 week incubation period between infestation and presentation of symptoms. However, in individuals with prior exposure to scabies, the incubation period is much shorter: as little as 1β4 days.
There are usually relatively few mites on a normal, healthy person (who is infested with scabies) β about 11 females in burrows. Scabies are microscopic although sometimes they are visible as a pinpoint of white. The females burrow into the skin and lay eggs there. Males roam on top of the skin, although can also occasionally burrow.
Diagnosis
Signs and symptoms of early scabies infestation mirror other skin diseases, including dermatitis, syphilis, allergic reactions, and other ectoparasites such as lice and fleas.
Generally diagnosis is made by finding burrows - which often may be difficult because they are scarce, and because they are obscured by scratch marks. If burrows are not found in the primary areas known to be affected, the entire skin surface of the body should be examined.
The suspicious area can be rubbed with ink from a fountain pen or alternately a topical tetracycline solution which will glow under a special light. The surface is then wiped off with an alcohol pad; if the person is infected with scabies, the characteristic zigzag or S pattern of the burrow across the skin will appear.
When a suspected burrow is found, diagnosis may be confirmed by microscopy of surface scrapings, which are placed on a slide in glycerol, mineral oil or immersion in oil and covered with a coverslip. Avoiding potassium hydroxide is necessary because it may dissolve fecal pellets. Positive diagnosis is made when the mite, ova, or fecal pellets are found. Although this sounds simple in practice, actual detection of scabies sites is very difficult - requiring the scraping of dozens of suspicious lesions down to the superficial dermis. This will result in minor bleeding in spots. Even a negative (not finding any mites) scraping will not completely rule out scabies. Sometime, the best diagnosis is by the history, physical findings and noticing response to effective topical treatment.
Management
Medications
Topical
- Permethrin 5% is topical medication of choice. Toxicity may resemble allergic reactions. It is applied to the skin before bedtime and left on for about 8 to 14 hours, then showered off in the morning. This is repeated until tube is finished or until rashes disappear (regardless of physician's instructions, it must be applied from the top of the head to the bottom of the feet).
- Eurax (USP Crotamiton) This is not a cure but helps to relieve itch(pruritis)
- Malathion Applied for 24 hours; effective in killing both adults and eggs.
- Lindane (Kwellada): For use with patients where permethrin has failed or is contraindicated.
- There is some evidence that a 10% sulfur ointment in petroleum jelly applied topically is effective. It is cheap and readily available over-the-counter. It also has the advantage of being able to be used in pregnant women and infants under two months of age.
- Neem oil is deemed very effective in the treatment of scabies although only preliminary scientific proof exists which still has to be corroborated, and is recommended for those who are sensitive to permethrin, a known insecticide which might be an irritant. Also, the scabies mite has yet to become resistant to neem, so in persistent cases neem has been shown to be very effective.
- Tea tree oil at 5% is currently under investigation as to its effectiveness. In one study, it was more effective than commercial medications against the scabies mite in an in vitro situation.
Oral
A single dose of Ivermectin has been reported to reduce the load of scabies but another dose is required after 2 weeks for full eradication. In 1999, a small scale test comparing topically applied Lindane to orally administered Ivermectin found no statistically significant differences between the two treatments. As Ivermectin is easily administered (not requiring a rub down of the whole body like lindane or permethrin twice per treatment), compliance is much better. Ivermectin is used in eradication programs of many parasites of both human and animal. Side effects may include mild abdominal pain, nausea, vomiting, myalgia and/or
