Non-Viral Skin Infections

OVERVIEW

Skin infections and infestations may be caused by bacteria, fungi, or parasites and can affect the skin, hair follicles, nails, or deeper soft tissues. Their appearance and severity vary considerably, and accurate diagnosis is important for appropriate treatment and prevention of complications.

BACTERIAL SKIN INFECTIONS

Cellulitis
A spreading bacterial infection involving the deeper skin and subcutaneous tissues, causing redness, warmth, swelling, and tenderness. Fever or other systemic symptoms can accompany more extensive infection.
Impetigo
A contagious superficial bacterial infection, particularly common in children, characterized by pustules, erosions, and characteristic honey-colored crusting, often around the nose, mouth, or extremities.
Folliculitis
Inflammation of the hair follicles appearing as small red bumps or pustules centered around hair shafts. Bacterial folliculitis is commonly caused by Staphylococcus aureus, although folliculitis also has noninfectious causes.
Furuncles (Boils) & Carbuncles
Deeper bacterial infections involving hair follicles and surrounding tissue. Furuncles form painful, inflamed, pus-filled nodules; carbuncles involve a deeper interconnected group of infected follicles and may produce multiple areas of drainage.
Skin Abscesses
Localized collections of pus within the skin or underlying soft tissue, typically presenting as painful, swollen, warm, fluctuant nodules or masses. Treatment differs from uncomplicated cellulitis because drainage is often an important part of management.
Infected or Inflamed Cysts
Epidermal and other cutaneous cysts can become acutely inflamed or secondarily infected, producing rapid enlargement, redness, tenderness, and sometimes drainage. Inflammation of a cyst does not necessarily mean bacterial infection, which is an important distinction during evaluation.
Erysipelas
An acute bacterial infection involving the superficial dermis and lymphatic vessels, typically producing a bright red, swollen, tender, sharply demarcated area, often accompanied by fever or other systemic symptoms. The legs and face are commonly affected.
Secondary Bacterial Infection of Damaged Skin
Eczema, excoriations, wounds, ulcers, insect bites, and other disruptions of the skin barrier can develop secondary bacterial infection, producing increasing redness, pain, crusting, drainage, or surrounding inflammation.

FUNGAL SKIN INFECTIONS

Dermatophytosis (Tinea / Ringworm)
Superficial fungal infections caused by dermatophytes that involve keratinized tissues of the skin, hair, and nails. Appearance varies by location and may include scaling, itching, redness, cracking, hair loss, or characteristic advancing borders.

Common forms include:
- Tinea corporis (Ringworm) — typically produces expanding, scaly plaques with a more active outer border and variable central clearing.
- Tinea pedis (Athlete's Foot) — commonly causes scaling, peeling, fissuring, or itching between the toes or on the soles of the feet.
- Tinea cruris (Jock Itch) — affects the groin and upper inner thighs, producing an itchy, well-defined, scaly rash.
- Tinea capitis (Scalp Ringworm) — affects the scalp and hair shafts and may cause scaling, inflammation, broken hairs, or areas of hair loss.
- Tinea unguium (Onychomycosis) — fungal infection of the nails causing thickening, discoloration, brittleness, and separation of the nail from the nail bed.
  👉 Learn more: Nail Disorders
Candida (Yeast) Infections
Candida species can cause infection in warm, moist, occluded areas, particularly the groin, beneath the breasts, abdominal folds, and other intertriginous areas. Cutaneous candidiasis commonly produces bright redness, maceration, soreness or itching, and characteristic satellite papules or pustules surrounding the main area of inflammation.
Pityriasis (Tinea) Versicolor
A superficial yeast-related condition caused by Malassezia, producing lighter, darker, or pink finely scaling patches, most commonly on the chest, back, shoulders, and neck. Altered pigmentation can persist after the active yeast has been controlled, which can make treatment response difficult to judge by color alone.

PARASITIC SKIN INFESTATIONS

Scabies
A contagious skin infestation caused by the Sarcoptes scabiei mite, characterized by intense itching, often worse at night, with papules, nodules, excoriations, or thin burrows. Common sites include the finger webs, wrists, waistline, underarms, and genital region.
Demodex Infestation (Demodicosis)
Demodex mites normally inhabit facial hair follicles and sebaceous glands. Excessive proliferation can produce facial redness, scaling, follicular papules and pustules, itching, or burning and can resemble or coexist with rosacea.
Travel-Associated Parasitic Skin Infestations
Exposure during travel, particularly in tropical and subtropical regions, can result in other parasitic skin conditions. Travel history, geographic exposure, and the appearance and progression of the skin lesions are important diagnostic clues.

TICK-BORNE SKIN INFECTIONS

Lyme Disease (Tick-Borne Bacterial Infection)

Lyme disease is a bacterial infection caused primarily by Borrelia burgdorferi and transmitted through the bite of infected black-legged ticks. The infection is particularly relevant in Northern Illinois and neighboring Wisconsin, where wooded areas and outdoor activities increase opportunities for tick exposure.

Early recognition and treatment are important because untreated Lyme disease can progress beyond the skin and involve the joints, nervous system, or heart.

⚠️ ERYTHEMA MIGRANS — AN IMPORTANT EARLY SKIN FINDING

Erythema migrans is often the earliest recognizable manifestation of Lyme disease. It typically develops as an expanding red or pink patch at or near the site of an infected tick bite.

Typical features include:

Gradual enlargement over several days
An expanding patch that may be uniformly red or pink or develop areas of central clearing
May develop the familiar “bull's-eye” appearance, but often does not
The lesion is often relatively asymptomatic, but localized itching, burning, stinging, or warmth can occur
May be accompanied by flu-like symptoms, including fatigue, headache, fever, chills, muscle aches, or joint aches
May continue to expand and become quite large if untreated

Recognizing erythema migrans is particularly important because early Lyme disease is readily treatable with appropriate antibiotic therapy. Diagnosis at this stage allows treatment before later neurologic, cardiac, or joint manifestations develop.

WHEN TO SEEK MEDICAL EVALUATION

Skin infections and infestations can resemble inflammatory, allergic, and other dermatologic conditions, and incorrect self-treatment can delay appropriate care.

Medical evaluation is important for:

Rapidly spreading or worsening redness, swelling, warmth, or pain
Pus, drainage, crusting, or a painful enlarging lesion
Fever or other systemic symptoms
Recurrent boils, abscesses, folliculitis, or other skin infections
Persistent or recurrent fungal infections
Intense or persistent unexplained itching or suspected parasitic infestation
An expanding rash following possible tick exposure
Skin changes that persist despite treatment or remain unexplained

Accurate diagnosis helps distinguish bacterial, fungal, parasitic, and noninfectious skin conditions and guides appropriate treatment.

Schedule a Dermatology Evaluation

Skin infections and infestations require accurate diagnosis to determine appropriate treatment.

📞 Call (847) 518-9999 to schedule a dermatology evaluation.

Medical Disclaimer
This information is provided for educational purposes only and does not replace individualized medical evaluation. Treatment recommendations depend on clinical findings, diagnostic requirements, and patient-specific factors. Outcomes may vary, and no specific medical result can be guaranteed.

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