Scabies rash is a developed form of scabies. To understand scabies rash we must first understand scabies and what the nature of this skin condition is.
What is Scabies?
Scabies is a contagious skin condition. The name itself is derived from the Latin word “scabere” meaning “to scratch”. It is caused by a very small itch mite that burrows into the skin causing a severe allergic reaction and thus the constant itching. Scabies is not an infection but an infestation, which basically refers to any parasitic disease caused by insects or worms. Infestations require an organism to live on or within a host, usually human. The average number of scabies mite on an infested person is 12.
Scabies Rash Description:
Scabies produces a skin rash in the form of small, pus-filled bumps and blisters. These pus-filled blisters are medically called “papules” and may contain blood crusts. Scabies rash usually involves the webs between the fingers, the hands, the wrists, the backs of the elbows, the knees, around the waist and umbilicus (the depression in the center of the surface of the stomach), the soles of the feet, the armpits, around the nipples, the genital area and the buttocks. Only in immunosuppressed patients or infants does scabies rash spread to the face, the scalp, the head, the neck and the palms.
Scabies rash description in the textbooks always mentions burrows or tunnels in the skin. These are tiny, threadlike grooves that leave a trail of linear or s-shaped tracks in the skin often accompanied by the minute papules. The s-shaped, track-like burrows appear as grey, red or brown lines in the affected areas of the skin. Scratching destroys these burrows.
Scabies rash varies in appearance according to the manifestation of the papules. To the naked eye, the papules can look like hives, tiny insect bites, pimples or knots under the skin. In some severe cases, people develop scaly skin patches that look like eczema.
Scabies modes of transmission:
Scabies is transmitted via direct skin-to-skin contact. It is also transmitted via sexual intercourse and has been recently considered a sexually transmitted disease (STD). Scabies is a sanitation-related infestation. It is mostly spread between members of the homeless population due to the lack of public facilities for bathing and laundry, also carelessness in insecticide application to bedding in shelters which causes the mites to inhabit the mattresses and pillows and further spread the infestation. There have also been many scabies outbreaks in nurseries, residential homes, refugee camps and other urban areas all over the world. Scabies rash is a very common condition.
Difference between Scabies and Other Skin Conditions:
What distinguishes scabies rash from other skin conditions like acne or mosquito bites is the constant itching. The itch is a result of the mites moving underneath the skin and depositing eggs into the shallow burrows. Linear stretch marks resulting from atrophy of the dermis skin layer are often mistaken for scabies burrows and tunnels. Bedbug infestations could also be mistaken for scabies rash. However bedbug infestations are not characterized by the severe itching and there are many signs to be detected for presence of nymphs in the house. Bedbug infestations are also not related to personal hygiene because you can find the nymphs in five star hotels as well as the filthiest of shelter homes.
Scabies rash could be so intense and relentless that it would keep a person awake all night. Severe itching (pruritis) can lead to constant scratching. This might be dangerous when a papule pops and sores are formed. Sores make a perfect site for infection. Due to non-stop scratching, bacteria strains like Staphylococcus aureus or beta-hemolytic streptococci enters the blood and leads to sepsis. This is a severe response of the body when bacteria or germs reach bloodstream and it could be life-threatening.
Scabies Rash Symptoms:
Scabies rash is a key diagnostic element for scabies as well as itching. No scabies infection occurs without rash. However, symptoms of scabies might not appear as soon as the infection occurred. This is the case for most people who are exposed to scabies for the first time. Early scabies infestation takes up to three months and not less than four weeks to become symptomatic. During this asymptomatic incubation period, a person with scabies can still spread the infection. Symptoms of scabies usually start with mild itching. The rash appears next as the itching progresses into the insidious form that deprives people of sleep. If the person has had scabies before, it only takes 2-3 days for the itching to start.
Post-Scabies Rash (The Secondary Inflammation):
The secondary inflammation or post-scabies rash is a common complication that takes place after scabies has been treated. Mostly this secondary inflammation is wrongfully believed to be a rebound infestation and people wear their skin off with chemical agents and antibiotics. This is not the case. Post scabies rash occurs due to a heightened level of white blood cells in the human body due to the fighting of the parasitic mites during infestation. Even long after the body is treated from scabies, the level of the white blood cells takes long to go back to normal level, thus the hypersensitivity reaction. This inflammation works itself out after a month or so with the aid of mild topical anti-inflammatory agents.
Treatment of Scabies Rash:
Scabies rash patients should seek medical attention as soon as possible. Every person who came in contact with the scabies patient should seek treatment as well, whether it was a family member or a sexual partner. Scabies –as previously mentioned- remains asymptomatic for a period of 2-6weeks if it has not been acquired before.
Scabies rash should be treated medically as soon as possible. However, some home remedies and folk recipes are sought to prevent rebound infestation and as a mild relief from the aggressive symptoms.
Home Remedies and Folk Recipes:
- Wash all linens, clothing and towels with hot water 50°C or above. After washing them, use a hot dryer to dry them off. Air drying might create a habitable environment for the parasites. Ironing bed sheets and linens is also an effective method to ensure death of the mites after washing.
- Clean every piece of furniture susceptible to be contaminated thoroughly or store it away for a week to contain the mites until they die. Mites can live inside mattresses and on the surfaces of non-animate objects for a few days outside the host’s body, so it is better to take precautions when dealing with furniture and non-washable objects.
- Fumigate living areas or furniture.
- Vacuum carpets, furniture, car interiors and bedding. Throw away vacuum-cleaner bags when finished.
- Check on your pets and treat if any symptoms of mange infestation are present (itching, severe hair loss, etc.).
- Personal hygiene is a must. Trim your nails regularly and clean the nail beds using a soft nail brush. This is an important step to remove any present eggs or mites. Regular bathing and cleanliness should be among top priorities of healthcare providers and caregivers dealing with scabies patients.
- Some home remedies suggest using water diluted with neem or tea-tree oil. Apply this mixture to affected areas and brush gently. Take care not to brush vigorously so as not to damage the skin.
- A mixture of rosemary oil and castor oil is applied to the skin twice daily. The mixture is said to smother, kill and extract the mites as well as decrease the intensity of the inflammation.
Medical Treatment for Scabies Rash:
Treatment regimen for scabies rash should be as follows:
- Mite killer (e.g. permethrin): This is the first line treatment for scabies rash. Permethrin 5% cream is applied to clean, dry skin from the neck down and left on overnight. Permethrin is the safest and most efficient mite killer and is used in children without concern.
- Mite killer (e.g. lindane): This is the second line treatment for scabies rash. Lindane lotion is applied to clean, dry skin from neck down but should be washed in less than 8 hours or else it would cause seizures. Lindane is also a highly toxic drug and should be kept away from eyes and mucous membranes. Lindane lotion should be stopped if irritation or redness occurs. Lindane is teratogenic and should never be applied to breastfeeding mothers or pregnant women. Lindane should only be prescribed in case of failure of other scabies treatment regimens.
- Anthelmintic and scabicide (e.g. ivermectin): This is the only oral medication given for treatment of scabies. It is only limited to cases that resist treatment with topical scabicides. It has a high toxic profile and may not be tolerated by the body so it is only given in small doses, 200 micrograms per kilogram body weight.
- Scabicidal agent and antipruritic (e.g. crotamiton): Crotamiton 10% lotion or cream is given in rare cases where resistance to other topical agents (e.g. permethrin) has been reported. It has a high risk of toxicity when absorbed by the body so it shouldn’t be applied to sensitive, irritated skin with open sores. It is not safe for use in children.
- Topical sulfur in petrolatum: It is applied as cream or ointment. One of the benefits of sulfur preparations is their high safety profile. You should be cautious if you have sulfa allergy and a sensitivity test is a must before applying sulfa topical agents.
- Antihistamines (e.g. diphenhydramine): These are very helpful as a relief from the itching. Antihistamines are given concomitantly with scabicides.
- Organophosphate scabicide (e.g. malathion): Malathion 0.5% lotion is given in very low doses to treat scabies rash. It is very irritating and might cause organophospate poisoning if ingested so it should be kept away from children. Safety for use in children has been proved, although the drug is not approved by the FDA for treatment of scabies.
Scabies Rash in Animals:
Canine or feline scabies is known as mange. Parasitic mites that cause mange embed themselves in the skin or hair follicles of the infested animal. There are two types of mange; demodectic and sarcoptic. Demodectic mange, also known as “the red mange” is caused by the proliferation of the mites that are present on the animal’s skin normally. Overpopulation of the parasites is due to oversensitivity of the animal to the demodectic mange mites or failure of the animal’s immune system to keep the mites under control.
Demodectic mange could be either localized or generalized. The generalized form occurs when the infestation spreads over large areas of the skin or the animal’s entire body. Demodectic pododermatitis is a very severe form of mange, affecting only the foot of the animal yet usually accompanied with bacterial infection. Demodectic mange is not contagious, according to most theories. However, there are assumptions that dog-to-dog transmission occurs when the dog’s immune system is compromised. Demodectic mites cannot be transferred to cats or to humans, which makes it a rather safe infestation.
Sarcoptic mange, on the other hand, is highly contagious. It could be transmitted from dogs to all kinds of species, humans included. Sarcoptic mange symptoms are similar to human scabies including severe itching, reddening and crusting of the infested sites. The damage occurs from the intense scratching and biting of the itchy skin patches. This leads to bacterial infection
In both demodectic and sarcoptic mange, the animal suffers a mild-to-severe form of hair loss.
Scabies Rash in Children:
Scabies rash is worse in children. It is widespread and very irritating. The child would refuse to eat or sleep, and would scratch constantly.
Scabies Rash Complications:
Scabies rash is generally curable and resolves within the assigned course of treatment which takes no longer than a few weeks. However, scabies complications are very serious and require further treatment that even goes as far as hospitalization. Like sepsis, scabies complications arise from intense scratching which leads to infection of skin and the spread of bacterial infection via bloodstream.
Scabies incognito is a widespread atypical infection resulting from applying topical corticosteroids to the skin. Scabies lesions look unusual and may be difficult to diagnose.
Impetigo is a very common form of scabies rash complication. It is a highly contagious bacterial infection that usually resolves within a week of treatment. There are two types of impetigo. Non-bullous impetigo affects the skin around the nose and mouth forming sores which lately burst into yellow-brown crusts. Bullous impetigo affects the body from the neck down to the waist, developing honey-colored, oozing blisters called bullae. These bullae burst leaving a yellow crust.