Fungal Infections: Types, Symptoms and Treatment

Types of fungal infection

Superficial (skin, hair and nails)

Deep and systemic

• Aspergillosis: mold infection of the lungs, sinuses or bloodstream.
• Histoplasmosis, blastomycosis and coccidioidomycosis (valley fever): caught by breathing in spores from soil in particular regions. Often mild, but can be severe.
• Cryptococcosis: lung and brain infection, mainly in advanced HIV.
• Pneumocystis pneumonia: in people with weakened immunity.
• Invasive candidiasis and mucormycosis: serious infections in hospital patients and people with uncontrolled diabetes.
• Sporotrichosis: skin infection from thorns or soil, spreading along lymph channels.

Fungal infection of the hair and scalp

What causes it

Tinea capitis is caused by dermatophyte fungi, mainly Trichophyton tonsurans in the US, and Microsporum canis from cats and dogs. The fungi invade the hair shaft and the skin of the scalp. It spreads through close contact, shared combs, brushes, hats, pillows and helmets, and from pets. It is most common in children aged 3 to 7 and is uncommon in adults.

Other causes of fungus on the hair include:

• piedra: firm nodules stuck to the hair shaft, black (Piedraia) or white (Trichosporon), seen mainly in tropical climates. See fungal infection of the hair
• seborrheic dermatitis: linked to Malassezia yeast, causing dandruff and greasy scale, without hair breakage

Symptoms of fungal infection in the hair

• round or irregular patches of hair loss
• scaling like dandruff, often with itching
• black dots: hairs broken off at the scalp surface
• gray, dull, broken hairs ("gray patch" type)
• corkscrew or comma-shaped hairs, twisted broken hairs seen on close examination (dermoscopy), especially in children of African descent
• pustules, crusting or tender swollen lymph nodes at the back of the neck
• kerion: a painful, soft, pus-filled swelling, an intense immune reaction that can cause scarring if not treated promptly

Diagnosis

• examination with a magnifying dermatoscope
• Wood's lamp (ultraviolet light): some Microsporum infections glow green
• KOH microscopy of scraped scale and plucked hairs
• fungal culture, which identifies the species and guides treatment

Treatment

Creams alone cannot reach fungus inside the hair shaft, so tinea capitis needs oral antifungal medicine:

• griseofulvin for 6 to 12 weeks, taken with fatty food
• terbinafine for 4 to 6 weeks, especially effective for Trichophyton
• fluconazole or itraconazole as alternatives

Alongside tablets:

• antifungal shampoo (selenium sulfide 2.5% or ketoconazole 2%) 2 to 3 times a week reduces spread
• household members may also use the shampoo, and should be checked
• clean or replace combs, brushes and hats, and check pets
• children can usually return to school once treatment has started

Hair usually regrows over months, unless a kerion has caused scarring.

Causes and risk factors for fungal infections

• warm, moist skin: sweating, tight shoes, skin folds
• shared showers, pools and gyms
• contact with infected people, animals or soil
• diabetes, obesity and poor circulation
• antibiotics and corticosteroids
• weakened immune system: HIV, chemotherapy, transplant drugs
• nail injury and aging (nail fungus)

Diagnosis

Skin infections are often diagnosed by appearance, confirmed by KOH microscopy or culture of skin scrapings, nail clippings or hair. Deep infections need blood tests, antigen tests, imaging, cultures and sometimes biopsy.

Treatment

• Topical antifungals (clotrimazole, miconazole, terbinafine, ketoconazole) for athlete's foot, jock itch, ringworm and tinea versicolor, usually for 2 to 4 weeks, continuing 1 to 2 weeks after the rash clears.
• Oral antifungals for scalp and hair, widespread skin infection, and most nail infections. Liver function monitoring may be needed with some drugs.
• Antifungal shampoos for tinea versicolor and seborrheic dermatitis.
• IV antifungals (echinocandins, amphotericin B, voriconazole) for invasive infections.

Avoid using steroid creams alone on an undiagnosed rash: they can make fungal infections spread and harder to diagnose.

Prevention

• keep skin dry, especially between toes and in skin folds
• wear sandals in shared showers and pools
• change socks and underwear daily
• do not share combs, hats, towels or razors
• treat pets with patchy hair loss
• keep diabetes well controlled

Frequently asked questions

What does a fungal infection in the hair look like?

It usually causes scaly, itchy patches on the scalp with broken hairs, black dots where hairs have snapped off, and patchy hair loss. Some children develop pustules, swollen glands at the back of the neck, or a painful, boggy swelling called a kerion.

What causes fungal infection of the hair?

It is usually caused by dermatophyte fungi such as Trichophyton tonsurans or Microsporum canis, which invade the hair shaft. It spreads by close contact, shared combs, brushes and hats, and from cats and dogs. Children are most often affected.

How is a scalp fungal infection treated?

Scalp and hair fungal infections need oral antifungal tablets such as griseofulvin or terbinafine for several weeks, because creams cannot reach fungus inside the hair. Antifungal shampoo reduces spread to others. Household members and pets may need checking.

What are corkscrew hairs?

Corkscrew hairs are short, twisted broken hairs seen with a dermatoscope in tinea capitis. They are a useful clue to fungal infection of the scalp, especially in children with tightly curled hair, and help doctors tell it apart from other causes of hair loss.

Are fungal infections contagious?

Many are. Ringworm, athlete's foot, jock itch and tinea capitis spread through skin contact, shared items and surfaces, and some come from animals. Yeast infections and tinea versicolor are not usually considered contagious. Deep infections from soil spores do not spread between people.