When microscopic mites known as Sarcoptes scabiei burrow into human skin and lay eggs, they produce itchy bumps or blisters known as scabies. Scabies is treatable with a variety of topical medications that work to kill the mites; however, the condition spreads very easily, increasing the likelihood of complications among some people.

Itching and Scratching

Scabies begins as tiny bumps on the skin; however, persistent scratching of these itchy bumps can cause them to turn into bigger sores covering a larger surface area of the skin. According to the Cleveland Clinic, the intense itchiness can be especially bothersome at night. Those with scabies are often unable to sleep and spend their nights scratching the itchy sores. The sensation of itchiness often spreads across the entire body. Consequently, infected individuals may develop fatigue and moodiness due to lack of sleep. Sleep deprivation may also lead to problems concentrating on work or school during the daytime.

Norwegian (Crusted) Scabies

Very severe cases of scabies called Norwegian, or crusted, scabies can occur in people whose immune systems are compromised, such as those with human immunodeficiency virus (HIV) or leukemia, as well as in people with physical or mental disabilities--for example, Down syndrome, dementia, spinal cord injury or paralysis. According to the Centers for Disease control, because of their depressed nervous systems, immune functioning and/or mental status, these people may not experience the usual itchiness associated with scabies. They will, however, develop crusty, scaly sores covering the skin. They may have millions of mites on their skin, leading to highly contagious, widespread infection over large areas of the body. Treatment of crusted scabies can be much more difficult as topical creams typically used to treat scabies may not successful penetrate the thickened, crusty skin.

Bacterial Infection

According to the Mayo Clinic, persistent scratching of scabies bites can create open sores on the skin that are vulnerable to penetration by bacteria. Secondary bacterial infections caused by these breaks in the skin are a known complication of scabies. One type of infection commonly caused by staphylococcus aureus or group A streptococcus bacteria is impetigo--a skin condition characterized by red, blistering and oozing sores that eventually crust over and turn yellowish-brown in color. While often these sores are painless and filled with fluid, they can become pus-filled, ulcerated and very painful. The Centers for Disease Control adds that, while impetigo is usually a superficial infection, it can spread, leading to an inflammation of the kidneys known as glomerulonephritis.