Microbiology of Scabies

Morphology and Life Cycle of Sarcoptes scabiei

Scabies is a contagious skin infestation caused by the mite Sarcoptes scabiei. This ectoparasite burrows into the epidermis, causing intense itching and discomfort.

Introduction

Scabies is a dermatological condition resulting from infestation by the microscopic mite Sarcoptes scabiei. It primarily spreads through direct skin contact and is prevalent in overcrowded living conditions.

Morphology of Sarcoptes scabiei

• Size: Adult mites are approximately 0.3-0.5 mm in length.
• Shape: Oval and flattened dorsoventrally.
• Color: Light brown or white.
• Legs: Eight short legs, adapted for burrowing.
• Cuticle: Covered with fine transverse striations and spines.

Life Cycle of Sarcoptes scabiei

The life cycle of Sarcoptes scabiei consists of four stages:

1. Egg Stage: Female mites lay eggs inside burrows in the skin.
2. Larval Stage: Eggs hatch into six-legged larvae in about 3-4 days.
3. Nymph Stage: Larvae molt into eight-legged nymphs.
4. Adult Stage: Nymphs mature into adult mites, continuing the cycle.

Transmission and Pathogenesis

Scabies spreads through prolonged skin contact, with symptoms appearing after 4-6 weeks in primary infestations. The mites burrow into the epidermis, leading to hypersensitivity reactions characterized by severe pruritus and erythematous papules.

Diagnosis and Treatment

Diagnosis includes clinical evaluation and microscopic examination of skin scrapings. Treatment involves topical scabicides like permethrin and oral ivermectin in severe cases.

Conclusion

Sarcoptes scabiei is a microscopic parasite responsible for scabies, a widespread dermal infestation. Early diagnosis and treatment are crucial for preventing outbreaks.