"Rash" - what is it, definition of the term
«Rash» is an acute cutaneous eruption manifesting as erythema, papules, vesicles, or wheals, frequently accompanied by pruritus, edema, or tenderness; it results from irritants, allergens, infectious agents, or systemic disorders and may appear localized or diffuse according to the underlying cause.
Detailed information
Skin eruptions triggered by ectoparasite bites present as localized redness, papules, or vesicles. Primary manifestations include itching, swelling, and occasional pain. Lesions may coalesce into larger patches if multiple bites occur in close proximity.
Ticks introduce pathogens while their mouthparts embed in the dermis, producing a circular erythema often termed a “target” pattern. The central area may become necrotic within 24–48 hours. Systemic signs such as fever, headache, or joint pain can accompany the cutaneous response, indicating potential transmission of bacterial or viral agents.
Bed‑bugs generate linear or clustered wheals that correspond to feeding sites. Bites are typically painless at the moment of penetration; delayed pruritus emerges after several hours. Scratching may lead to excoriations, increasing risk of secondary infection.
Lice infestations cause irritant dermatitis confined to areas where the insects cling, such as the scalp, neck, or pubic region. The reaction consists of tiny papules surrounded by a thin erythematous halo. Persistent scratching can produce crusted lesions and hair loss in severe cases.
Fleas produce punctate erythema with a central punctum, frequently appearing on the lower extremities. Rapid onset of intense itching is characteristic. In sensitized individuals, a papular urticaria pattern may develop, featuring multiple raised lesions distributed over the body.
Common diagnostic considerations:
- Temporal relationship between bite exposure and lesion appearance.
- Distribution pattern matching typical feeding behavior of the arthropod.
- Presence of systemic symptoms suggesting infectious transmission.
Management strategies focus on symptomatic relief, wound hygiene, and eradication of the offending parasite. Topical corticosteroids or antihistamines reduce inflammation and pruritus, while antimicrobial therapy addresses secondary bacterial involvement. Environmental control measures—such as regular laundering, vacuuming, and targeted insecticide application—prevent recurrence.