Scabies : Causes, symptoms, diagnosis, treatment, prevention and complications

writes : khalipha Justice / reviewed : Abdullahi Sa'id PH.D

Overview

Scabies is a parasitic infection caused by the Sarcoptes scabiei mite. The mite burrows into the skin and lays eggs, causing an allergic reaction that leads to intense itching and rash. Scabies is a common condition worldwide, affecting millions of people each year. It is more prevalent in overcrowded living conditions and among people with compromised immune systems. Scabies can be easily treated with medication, but it is important to take steps to prevent its spread.

Definition

Scabies is a skin infestation caused by the Sarcoptes scabiei mite. The mite burrows into the skin and lays eggs, causing an allergic reaction that leads to intense itching and rash. The itching is often worse at night and can be severe. Scabies is highly contagious and can spread quickly through close contact with infected individuals.

Classification

Scabies can be classified into two types: classical scabies and crusted scabies. Classical scabies is the most common form and is characterized by the presence of small, red bumps or blisters on the skin. Crusted scabies, also known as Norwegian scabies, is a more severe form of the condition that is characterized by thick, crusty patches of skin that contain large numbers of mites. Crusted scabies is more contagious than classical scabies and can be difficult to treat.

Causes

Scabies is caused by the Sarcoptes scabiei mite. The mite burrows into the skin and lays eggs, causing an allergic reaction that leads to intense itching and rash. The mites can survive for several days without a host and can be transmitted through close contact with infected individuals. Scabies is more prevalent in crowded living conditions, such as nursing homes, prisons, and refugee camps.

Causative Agent

The causative agent of scabies is the Sarcoptes scabiei mite. This mite is a tiny, eight-legged parasite that burrows into the skin and lays eggs. The mites can survive for several days without a host and can be transmitted through close contact with infected individuals.

Mode of Transmission

Scabies is highly contagious and can be transmitted through close contact with infected individuals. The mites can be transferred through skin-to-skin contact or by sharing clothing, towels, and bedding. Scabies is more prevalent in crowded living conditions, such as nursing homes, prisons, and refugee camps.

Incubation Period

The incubation period for scabies is typically two to six weeks. During this time, the mites burrow into the skin and lay eggs, leading to the onset of symptoms. The itching and rash may take several days to develop after the initial infestation.

Signs and Symptoms

The signs and symptoms of scabies include intense itching and a rash that may appear as small, red bumps or blisters. The rash is most commonly found in the folds of the skin, such as the webs of the fingers and toes, wrists, elbows, and buttocks. The itching is often worse at night and can be severe. In children, the rash may also appear on the head, neck, and face. Scratching the affected areas can lead to secondary bacterial infections and skin damage.

Diagnosis and Test

Diagnosis of scabies is usually made based on clinical presentation and history of exposure to infected individuals. A skin scraping or biopsy may be taken to confirm the presence of mites, eggs, or fecal matter. A dermatologist or other healthcare professional should be consulted for proper diagnosis and treatment.

Management and Treatment

Scabies can be easily treated with medication. Topical creams and lotions containing permethrin, lindane, or ivermectin are typically used to kill the mites and eggs. It is important to follow the directions of the medication and to treat all individuals who have come into close contact with the infected person. Clothing, bedding, and towels should be washed in hot water and dried on high heat to kill any remaining mites. Itching can be treated with over-the-counter antihistamines or topical corticosteroids. In severe cases, oral antibiotics may be necessary to treat secondary bacterial infections.

Prevention and Control

Preventing the spread of scabies involves avoiding close contact with infected individuals and their belongings. Clothing, bedding, and towels should not be shared with others and should be washed in hot water and dried on high heat. Regular hand washing and maintaining good hygiene can also help prevent the spread of scabies. In institutional settings, such as nursing homes and prisons, screening and treatment programs may be necessary to control outbreaks.

Risk Factors

The risk of developing scabies is higher in crowded living conditions, such as nursing homes, prisons, and refugee camps. Individuals with compromised immune systems, such as those with HIV/AIDS, cancer, or on immunosuppressive medications, may also be at higher risk for scabies. Children and elderly individuals are also at increased risk.

Complications

Complications of scabies may include secondary bacterial infections, such as impetigo or cellulitis, and the development of post-scabies nodules. These nodules are firm, raised bumps that may persist for several weeks after the infestation has been treated. Rarely, crusted scabies can lead to severe skin infections and sepsis, which can be life-threatening.

Outcome for Infected People

Scabies is a curable condition, and with proper treatment, symptoms usually resolve within several weeks. Itching may persist for several weeks after treatment, and post-scabies nodules may persist for several weeks to months. Complications are rare but can occur in severe cases.

Conclusion

Scabies is a common parasitic skin infection caused by the Sarcoptes scabiei mite. It is highly contagious and can spread quickly through close contact with infected individuals. Scabies can be easily treated with medication, but it is important to take steps to prevent its spread. Regular hand washing, maintaining good hygiene, and avoiding close contact with infected individuals and their belongings can help prevent the spread of scabies. Individuals who develop symptoms of scabies should consult a healthcare professional for proper diagnosis and treatment.

References:

• Chosidow O. Scabies. N Engl J Med. 2006;354(16):1718-27.
• Meinking TL, Serrano L, Hard B, et al. Comparative in vitro pediculicidal efficacy of treatments in a resistant head lice population in the United States. Arch Dermatol. 2002;138(2):220-4.
• Centers for Disease Control and Prevention. Scabies FAQs. https://www.cdc.gov/parasites/scabies/gen_info/faqs.html. Accessed February 22, 2023.
• Feldmeier H, Heukelbach J. Epidermal parasitic skin diseases: a neglected category of poverty-associated plagues. Bull World Health Organ. 2009;87(2):152-159.
• Micali G, Lacarrubba F, Verzì AE, Chosidow O, Schwartz RA. Scabies: advances in noninvasive diagnosis. PLoS Negl Trop Dis. 2016;10(6):e0004691.
• Salavastru C, Chosidow O, Janier M, et al. European guideline for the management of scabies. J Eur Acad Dermatol Venereol. 2017;31(8):1248-1253.
• Chosidow O. Clinical practices. Scabies. N Engl J Med. 2006;354(16):1718-27.
• CDC. Parasites – Scabies. Centers for Disease Control and Prevention. Published October 6, 2016. Accessed February 22, 2023.
• Workowski KA, Bolan GA; Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep. 2015;64(RR-03):1-137.
• O'Brien SD, Currie BJ, Krause VL. Scabies: diagnosis and treatment. BMJ. 2018;361:k2898.