Model Answer
0 min readIntroduction
Scabies is a contagious skin infestation caused by the mite *Sarcoptes scabiei*. It’s a common dermatological condition globally, particularly in crowded living conditions and areas with limited access to hygiene. The infestation results in intense pruritus (itching) and a characteristic skin rash. While often associated with poor hygiene, scabies can affect individuals of any socioeconomic status. Understanding the clinical presentation and potential complications is crucial for prompt diagnosis and effective treatment, preventing further spread and minimizing morbidity. This answer will detail the primary manifestations, lesion distribution, and complications associated with confirmed scabies in an adult.
(i) Primary Manifestations and Distribution of Lesions
The primary manifestation of scabies is intense pruritus, often worse at night. This is due to an allergic reaction to the mites, their eggs, and feces. The characteristic skin lesions are papules, vesicles, and excoriations (scratch marks). These lesions are typically small, red, and raised. Burrows, which are slightly elevated, serpiginous (snake-like) tracks created by the female mite burrowing into the skin to lay eggs, are diagnostic but can be difficult to visualize, especially in immunocompromised individuals or with secondary infection.
Pattern of Distribution
The distribution of lesions in adults is typically different from that in children. Common sites include:
- Interdigital spaces: Between the fingers and toes. This is a highly characteristic location.
- Wrist and elbow flexures: The creases of the wrists and elbows.
- Axillae: The armpits.
- Areolae: Around the nipples (especially in women).
- Umbilicus: Around the navel.
- Genitalia: In males, the penis and scrotum; in females, the vulva.
- Buttocks: Particularly the gluteal cleft.
- Belt line: Around the waist.
In immunocompromised individuals (e.g., HIV/AIDS, organ transplant recipients, those on immunosuppressants), a crusted or Norwegian scabies variant can occur. This presents with thick, hyperkeratotic (thickened skin) scales and minimal inflammation, often affecting the hands, feet, elbows, and scalp. These individuals may harbor a very large number of mites and are highly contagious.
(ii) Complications of Scabies
Scabies, if left untreated or inadequately treated, can lead to several complications:
- Secondary Bacterial Infection: Intense scratching can break the skin, allowing bacteria (typically *Staphylococcus aureus* or *Streptococcus pyogenes*) to enter, leading to impetigo, cellulitis, or even more serious infections like sepsis. This is the most common complication.
- Post-Streptococcal Glomerulonephritis: A rare but serious complication following streptococcal skin infection secondary to scabies.
- Eczematization: Chronic scratching can lead to lichenification (thickening of the skin) and eczema-like changes.
- Allergic Contact Dermatitis: Sensitivity to topical treatments (e.g., permethrin) can develop.
- Crusted Scabies (Norwegian Scabies): As mentioned earlier, this severe form is associated with a massive mite burden and is highly contagious. It can be life-threatening, particularly in immunocompromised individuals.
- Psychological Impact: Chronic itching and skin lesions can lead to anxiety, depression, and sleep disturbances.
- Rheumatic Fever: Though rare, there have been reported associations between scabies and rheumatic fever, particularly in children.
Diagnosis is typically clinical, based on the characteristic distribution of lesions and the presence of burrows. A skin scraping can be performed to identify mites, eggs, or fecal pellets under a microscope, but a negative scraping does not rule out scabies.
Conclusion
In conclusion, scabies presents with characteristic pruritic lesions distributed in specific body areas, and its diagnosis relies on clinical assessment and sometimes microscopic examination. Untreated scabies can lead to significant complications, including secondary bacterial infections, eczematization, and, in severe cases, crusted scabies and systemic sequelae. Prompt diagnosis and appropriate treatment with scabicides are essential to control the spread of infection and alleviate patient suffering. Public health measures focusing on hygiene and education are also crucial in preventing outbreaks, particularly in vulnerable populations.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.