Scabies has been known to mankind for more than 3000 years. It is an ancient worldwide disease affecting all races and social classes in every climate from arctic to equatorial regions. Scabies is caused by a mite which lays eggs in the human skin. These eggs then hatch and grow into adult mites which repeat this cycle, this means that the signs and symptoms of the skin condition can last for months or even years if not treated properly.
Scabies is a very common disease and globally, more than 200 million people are affected every year with a particularly high prevalence in poor tropical regions. It is an important public health problem worldwide and can occur at any age affecting both males and females equally.
History
Scabies which is basically a mite known as sarcoptes scabie. Humans discovered this mite in the 17th century and scabies might has been mentioned even in the old testaments of bible and many books of Shakespeare. You would be surprised to know that human scabies was the first disease in which the causative organism was discovered by using a microscope. This mite is oval pearl-like white organism with lots of legs and special structures on their legs known as suckers. At a time, about 10 to 12 mites can affect an individual.
Life cycle of a Mite
The life cycle of the mite is completed entirely on human skin and it starts when a pregnant mite attaches on the skin. This female mite dugs up a tunnel like structure on the human skin which is known as a "burrow". This burrow can be up to one centimeter long and the mite lays her eggs along the burrow. Each mite can lay up to 50 eggs.
During the life cycle, these eggs then hatch into larvae in three to four days and escape the burrow. The larvae then transform into next stage in their life cycle known as nymphs. And in the next four to seven days, these nymphs mature into adult males and females hence completing the cycle.
The burrows of the mites are often visible as very thin lines mostly less than one centimeter in length. Often scratching of these itchy burrows results in bacterial infection of skin so called secondary bacterial infection. The scabies mite are capable of surviving in the environment outside of the human body for up to three days in normal room conditions.
Classification
Schematic infestation can be classified into classical scabies which is the most common form and animal transplanted scabies which is acquired from animals like dogs horses etc. And lastly, we have crusted scabies or norwegian scabies. Here, the host may be colonized with many millions of mites. It is the most severe form of scabies and happens in people with weak immune system such as those caused by infections like HIV, blood cancers or chronic use of steroids or other drugs that suppress the immune system.
Risk factors for transmission of scabies
The risk factors for transmission includes poverty, overcrowding, poor hygiene, poor nutritional status, homelessness, dementia and immunosuppression. You can get scabies by coming in physical contact for a significant amount of time with someone who has it or you can also get scabies by using the same dolls, beddings clothes or other formites used by someone who has it.
How do you know if you have scabies
It can be asymptomatic for the first couple of weeks but the hallmark of the scabies is severe itching that usually worsens at night and typically appears four to six weeks after the initial infestation. In addition to itching, you can have skin lesions in the form of tiny red bumps that are usually present over the webs or fingers, inner aspects of wrists, underarms, umbilicus and perium lycal region. It can be anywhere on the body except on an adult's face. But in infants and elderly, all skin surfaces are susceptible to infestation. The patients also gave a history of similar complaints in family members and closed contacts which is very common.
Diagnosis
Diagnosis is mostly clinical and is based upon typical signs and symptoms. Typical symptoms, typical site of involvement, typical appearance of skin lesions, all of which that are mentioned above. Also not to forgets history of similar complaints in family members or closed contacts is very common.
The definitive diagnosis is made by microscopic identification of scabies mite eggs or fecal pellets also known as scabula.
What are different treatment options we have for treating scabies
Treatmeant can be basically divided into topical drugs which are creams and lotions applied over the skin and oral medications.
Topical medications
Permethrin kills both the adult mite as well as the eggs and is therefore highly effective after a single application. However in practice, the prescribed regime often involves two applications which is to be applied to the full body from neck down and 8 to 14 hours of contact period is required. So generally, apply it in the night and wash it off in the morning.
Benzyl benzoate has been used in 10 to 25 percent preparation in many countries including europe and australia but its use is limited by severe skin irritation.
Chrotomaton 10 has been favored in children due to its low toxicity profile. However, it has limited efficacy and multiple applications are usually required to achieve a satisfactory response.
Oral medication
Ivermectin is prescribed as a single dose of 12 milligram for adults and 6 milligram for children below 10 years of age. Often a second dose of ivermectin is given after 14 days. A second dose is required to kill all the eggs of the mite which can hatch after some time and can lead to a relapse.
Moxitectin is a newer agent that is being used to treat scabies. It has better retention in the skin and a much longer half-life than ivermectin, meaning that a single dose may be enough to eliminate the complete infestation. It also appears to prevent a reinfestation for a longer period of time compared with ivermectin.
Lifestyle modifications you should do to prevent scabies and its relapse
You need to kill all mites that may be present on your clothing, dolls and bedding by doing one of the following:
Wash them in hot water and dry them in a hot dryer or keep them in direct sunlight for at least two days
Items you cannot wash, you can wrap them in a closed plastic bag and keep them in sunlight for at least three days so that all the mites die.
Always remember that a good personal hygiene is the most important thing you can do to prevent scabies and its reinfection.