Cause of scabies is -

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Explanation

Scabies is a parasitic infestation of the skin caused by the microscopic human itch mite, Sarcoptes scabiei.
The female mite burrows into the epidermis (the outermost layer of skin) to lay her eggs.
The characteristic intense itching and rash are the result of a delayed hypersensitivity reaction to the mite, its eggs, and its feces.
Transmission occurs primarily through direct, prolonged, skin-to-skin contact with an infested person.

Option B: Bacteria cause infections like impetigo and cellulitis. They do not cause the primary burrowing infestation of scabies, although they can cause secondary infections if the skin is broken by scratching.
Option C: Ticks are arachnids, but they are different from mites. Ticks attach to the skin surface to feed on blood and are vectors for diseases like Lyme disease. They do not burrow into the skin to live and reproduce.
Option D: Viruses are infectious agents that cause diseases such as measles, chickenpox, or herpes. They are not parasites that infest the skin in the manner of scabies mites.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of Scabies as background academic context rather than a clinical decision trigger.
Correctly identifying the cause of scabies is crucial for initiating appropriate treatment with scabicides and preventing misdiagnosis and ineffective therapy.
A key nursing role is educating the patient and their family about the need to treat all close contacts simultaneously to break the cycle of transmission and prevent reinfestation.
Patients must be reassured that pruritus (itching) can persist for 2-4 weeks after successful treatment due to the ongoing allergic reaction to dead mites and their byproducts. This is not a sign of treatment failure.

How to Approach the Question

First, identify the core subject of the question, which is 'scabies'.
This is a factual recall question. Access your knowledge of common dermatological conditions and their causes.
Systematically evaluate each option. Recall that scabies is known for intense itching caused by a burrowing organism.
Differentiate between the types of pathogens: mites (parasites), bacteria, ticks (also arthropods, but with different behavior), and viruses.
Conclude that scabies is famously caused by the 'itch mite', making 'Mite infestation' the correct answer.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 p. 1633-1635

E6 Parks TextBook of Preventive & Social Medicine part 2 — Subpart B (pp 233-449 of 464) p. 97-99

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 4 p. 77-79

Practise the full RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.