Sarcoptes scabiei are mites or parasites that may be invisible to the naked eye, but causes immense damage to the human skin. These eight legged mites fall under the arthropod class Arachnida. They make the upper layer of the skin their home, forming burrows, where they lay eggs and multiply. The female mite hatches about 3-4 eggs a day. These mature in about 3 weeks, make more burrows and increase in population. There are many different species of these mites each having its own distinct host. The mites that affect an animal like a dog shall not be able to survive on a human skin and vice-versa.
Symptoms & Causes
The eggs, the tunnel, the waste deposits and the mites themselves, all contribute to the allergic reaction and severe itching for many weeks. Night is the time when the urge to itch is the strongest. These are very contagious and can mainly spread through physical contact with the affected person or through sexual physical contact. This is the reason it is also termed as a Sexually Transmitted Disease (STD). Other mode of transmission, which is unlikely, could be shaking hands, sharing clothes or bed clothes, in schools, nursing homes, etc. In humans, these mites mainly affect the fingers, wrist, elbows, genital areas, and buttocks, around the waist, shoulder blades, breasts and soles of the feet. Those with a very weak immune system or HIV are most likely to be affected with it.
Their symptoms are thin irregular grey, brown or red tracks with small blisters, which keep growing and become severe. They can affect any one in any age group from a child to the elderly. They are first noticed in the folds of skin like backs of the elbow, armpits, between the webs of the fingers. In small children they are first noticed on the scalp, face, neck and the palm of the hands. These mites can be viewed under a microscope. A doctor may also advise biopsy of the affected skin as these can also be mistaken dermatitis or eczema. These blisters also called papules contain blood and not necessarily mites. As these mites live not more than 3 days, hence there may be hundreds of blisters on the body but only 10-15 mites. When a healthy person is infected it takes about 50-60 days before the symptoms are noticed and itching begins. However the person can easily spread the infection from the day of the infection. Mostly under these circumstances the entire family is infected by the time it is detected. In patient with a history of scabies the symptoms are noticed within 2-3 weeks.
Crusted scabies is the most severe form of infection. They affect elderly or patients with low immune system, those hospitalized or HIV patients. As the name suggest the skin gets crusted and it is affected on a larger area. In should be noted that a person affected with crusted scabies do not itch neither are the blisters formed. There is thick crust formed which are creamy, grey, yellow or green in color.
As each species of these mites have their own host so transmission from an animal to a human is not possible. Even if the mites travel onto a human skin a very mild allergy may be noticed and cured in a few days.
Tea tree is considered as a home remedy which when mixed with cold water can kill these mites as they cannot survive below 20 degree Celsius. This is a cure only in very mild cases. A doctor’s intervention is required when the itching gets very severe. Medicated creams are best local treatment for scabies. These creams contain either 5% permethrin or benzyl benzoate or sulfur or crotamiton. Calamine lotions are also prescribed along with oral medication like Ivermectin. The itching may not stop soon after beginning the treatment. It takes a few weeks to get relief. The cream or shampoo should be applied as prescribed for the best results. Oral medication is the only way to treat crusted scabies as creams do not reach the inside of the skin. It should be noted that though itching is very intense it should be avoided as breaking the burrows does kill the eggs but gets prone to other skin infections.
The only way to prevent this infection from spreading is to maintain proper hygiene and washing the infected persons clothes and bed linen separately in cold water.