Fungal Infection

Fungal infections affect millions of people worldwide every year, ranging from common skin conditions like athlete’s foot and ringworm to serious internal infections that can be life-threatening for those with weakened immune systems.

Table of contents

• What Are Fungal Infections?
• Types of Fungal Infections
• Who Is Most at Risk?
• Signs and Symptoms
• How Fungal Infections Occur
• Diagnosis
• Treatment Options
• Prevention Strategies

What Are Fungal Infections?

Fungal infections, also known as mycosis (a disease caused by a fungus), are conditions that occur when harmful fungi invade the body^[1]. Fungi are living organisms that belong to their own kingdom, separate from plants and animals. They exist everywhere in our environment—in the air, soil, water, on plants, and even on and inside the human body^[1].

Scientists estimate there are millions of fungal species in the world, but only a few hundred can cause disease in people^[2]. While some fungi are helpful, such as those used to make bread rise or produce beer, others can cause infections. These harmful fungi include certain yeasts and molds that can affect various parts of the body^[1].

Worldwide, more than one billion people get a fungal infection each year^[2]. Fungal infections are among the most common skin conditions, affecting up to 20-25% of the world’s population at any given time^[11]. Serious fungal infections affect 300 million individuals, and it is estimated that more than 1.5 million people die from these infections each year^[8].

Types of Fungal Infections

Fungal infections can affect different parts of the body and are traditionally divided into three main categories based on where they occur^[1]:

Superficial Fungal Infections

Superficial fungal infections affect the surface of the skin, nails, hair, and mucous membranes such as the mouth, throat, or vagina^[1]. These are the most common types of fungal infections and include:

• Ringworm (dermatophytosis): Despite its name, ringworm is not caused by a worm but by fungi called dermatophytes (fungi that live off skin, hair, and nail cells). It can appear as a circular, red rash with a clear center. Ringworm can affect different parts of the body with different names—athlete’s foot affects the feet, jock itch affects the groin area, and tinea capitis affects the scalp^[1].
• Athlete’s foot (tinea pedis): This is the most common type of fungal infection. It typically affects the skin between the toes, causing it to turn white, peel, itch, sting, or burn. The infection thrives in warm, moist environments like sweaty shoes, locker rooms, and public showers^[1].
• Jock itch (tinea cruris): This infection affects the groin area and inner thighs, more commonly in men. It causes itching, redness, and a rash, often made worse by sweating and friction^[1].
• Nail fungus (onychomycosis): This infection affects fingernails or toenails, causing them to become discolored (yellow, brown, or white), thick, cracked, and brittle^[1].
• Yeast infections (candidiasis): Caused by Candida (usually a yeast called Candida albicans), these infections can affect the skin and mucous membranes. They include oral thrush (white patches in the mouth), vaginal yeast infections, esophageal candidiasis, and diaper rash. Candida normally lives on the body but can overgrow and cause symptoms when conditions are right^[1].
• Tinea versicolor (pityriasis versicolor): This causes skin discoloration and is caused by the fungus Malassezia^[1].

Subcutaneous Fungal Infections

These infections occur under the surface of the skin. They typically happen when fungi enter through a cut, wound, or injection site. Examples include eumycetoma and chromoblastomycosis^[1].

Deep or Systemic Fungal Infections

Deep fungal infections affect internal organs such as the lungs, brain, heart, or spread throughout the body. These are more serious and can be life-threatening, especially in people with weakened immune systems^[1]. Examples include:

• Environmental pneumonias: Infections like blastomycosis, histoplasmosis, and coccidioidomycosis (Valley fever) spread in different parts of the United States. People get infected by breathing in fungal spores from soil or dust^[2].
• Aspergillosis and mucormycosis: These mold infections typically affect people with weakened immune systems. The molds are everywhere in the environment but usually don’t cause illness in healthy people. Lung infections are the most common form^[2].
• Healthcare-associated infections: Serious fungal infections like Candida auris infections and candidemia (Candida infection in the bloodstream) can occur in healthcare settings like hospitals. Many affected patients already have weakened immune systems due to illness, injury, or medical treatments^[2].

Who Is Most at Risk?

Anyone can get a fungal infection, especially ones that affect the skin or nails^[1]. However, certain people are at higher risk for developing fungal infections, particularly severe ones. Risk factors include^[1][2]:

• Weakened immune system from conditions such as HIV/AIDS, cancer, or diabetes
• Taking immunosuppressant medications for autoimmune conditions or to prevent rejection after organ, stem cell, or bone marrow transplants
• Undergoing cancer treatments like chemotherapy
• Taking long-term or high-dose antibiotics
• Having poor circulation
• Being elderly or very young
• Having excess weight
• Being pregnant
• Spending many days in an intensive care unit
• Having large surface area wounds or burns

Fungal infections are more common in places on the body that trap moisture or have a lot of friction, such as skin folds in the groin, buttocks, or thighs^[1].

Signs and Symptoms

The symptoms of a fungal infection depend on the type and location of the infection^[1].

Skin infections can appear red, swollen, or bumpy. They may look like a rash, or you might see a lump under the skin. Common symptoms include^[1][4]:

• Itching and burning sensations
• Redness and irritation
• Scaly, flaky, or peeling skin
• Swelling
• Blisters

Nail infections cause nails to become discolored (yellow, brown, or white), thick, cracked, and brittle^[1].

Mouth and throat infections can cause a white coating or patches, pain when swallowing, and cracks at the corners of the mouth^[1].

Vaginal yeast infections cause itching, burning (especially when urinating), inflammation, and a discharge that may resemble cottage cheese^[4].

Deep infections affecting internal organs may cause pneumonia-like symptoms or meningitis. These are more serious and require immediate medical attention^[1].

How Fungal Infections Occur

Fungi reproduce by releasing tiny particles called spores into the air or environment. These spores are often present in the air and soil, where they can be inhaled or come into contact with body surfaces, primarily the skin^[6].

Fungal infections usually begin in the lungs or on the skin. Of the many spores that land on the skin or are inhaled into the lungs, most do not cause infection. However, fungi can multiply quickly when conditions are favorable, such as in warm and humid environments^[6].

You can acquire a fungal infection through^[1]:

• Direct contact with an infected person or animal
• Touching contaminated surfaces or items such as clothing, gym equipment, or mats
• Walking barefoot in public showers, locker rooms, or pool areas
• Breathing in fungal spores from soil or dust
• Entry through breaks in the skin such as cuts, wounds, or injection sites

Fungal infections are rarely passed from one person to another, except for some superficial skin infections^[6]. Most fungi are opportunistic pathogens, meaning they only invade the body when a weakened immune system permits them to do so^[3].

Sometimes fungal infections occur when the normal balance of microorganisms in the body is disrupted. For example, certain fungi like Candida normally live on body surfaces or in the intestine. The bacteria that usually live in these areas limit the growth of fungi. When people take antibiotics, helpful bacteria can be killed, allowing fungi to grow unchecked and cause symptoms^[6].

Diagnosis

A healthcare provider can often diagnose a fungal infection by looking at the affected area and asking about your symptoms^[1]. However, to confirm the diagnosis and identify the specific fungus, several tests may be performed:

• Microscopic examination: The provider may take scrapings of the skin, nails, or other affected areas and examine them under a microscope. This test, called a KOH preparation, can help confirm the presence of fungus^[1].
• Fungal culture test: A small sample of skin (biopsy) or fluid may be taken and sent to a laboratory to identify the specific fungus causing the infection. This helps determine the best treatment^[1].
• Blood tests: These may be used to detect fungal infections in the bloodstream or internal organs.
• Imaging tests: X-rays, CT scans, or other imaging may be needed to identify deep fungal infections affecting the lungs or other organs.

Accurate diagnosis is important because other conditions, such as psoriasis or eczema, can sometimes look similar to fungal infections^[1]. Fungal diseases are often misdiagnosed, which can delay appropriate treatment^[2].

Treatment Options

Fungal infections are usually treated with antifungal medications. The type of treatment depends on the location and severity of the infection^[1][12].

Topical Antifungals

For skin and nail infections, antifungal creams, ointments, gels, sprays, shampoos, or powders can be applied directly to the infected area. Many of these are available over the counter at pharmacies and should be used exactly as directed on the label^[12].

It’s important to avoid using products that combine antifungals with corticosteroids or steroids without medical advice, as steroids can worsen fungal skin infections^[12].

Oral Antifungals

More serious infections or those that don’t respond to topical treatments may require oral antifungal medications in the form of pills or liquids. These medications help a new, healthy nail or skin grow free of infection^[12].

Treatment with oral antifungals often takes a long time—sometimes months or years—to fully clear the infection. People may need to take them for 6 to 12 weeks or longer, especially for nail infections^[12].

Intravenous (IV) Antifungals

Deep or systemic fungal infections affecting internal organs require intravenous antifungal medications given in a hospital setting^[12].

Side Effects and Considerations

Antifungal medications can cause side effects, which tend to be more common and more severe than those from other types of medicines. Common side effects include abdominal pain, nausea, vomiting, diarrhea, headaches, and skin rashes. More severe side effects can include liver toxicity and kidney damage^[12].

It’s important to take antifungal medications exactly as directed by your healthcare provider, even if you start feeling better. Stopping treatment too early can allow the infection to return. If an antifungal causes serious side effects or symptoms don’t improve, talk to your healthcare provider^[12].

With few treatment options available, and increasing antimicrobial resistance (when fungi become resistant to medications), new antifungal development is needed^[2][12].

Prevention Strategies

While not all fungal infections can be prevented, you can reduce your risk by following these strategies^[1]:

• Practice good hygiene: Shower or bathe daily, especially after sweating or exercising. Dry yourself thoroughly, paying special attention to skin folds and areas between the toes.
• Keep skin clean and dry: Fungi thrive in warm, moist environments. Make sure to dry completely after bathing or swimming, and change out of wet clothing promptly.
• Wear breathable clothing: Choose loose-fitting clothes made from breathable fabrics. Avoid wearing tight clothing, especially in warm, humid weather. Change damp socks and undergarments regularly.
• Protect your feet: Wear sandals, flip-flops, or water shoes in public showers, locker rooms, pools, and other wet communal areas. Keep feet clean and dry, and change socks daily.
• Don’t share personal items: Avoid sharing towels, clothing, shoes, or personal care items with others, as these can spread fungal infections.
• Maintain a healthy immune system: Eat a balanced diet, get enough sleep, exercise regularly, and manage stress. These habits help keep your immune system strong.
• Be cautious with antibiotics: Use antibiotics only when prescribed and necessary, as they can disrupt the natural balance of bacteria and allow fungi to overgrow.
• Check pets regularly: Some fungal infections can spread from animals to humans. If your pet has skin problems, have them examined by a veterinarian.

If you tend to get repeated fungal infections, talk to your healthcare provider about additional prevention strategies^[1].