Fungal diseases, known medically as mycoses, are illnesses caused by fungi, which are microorganisms distinct from plants and animals. Fungi are present in all environments, and their microscopic spores can be found in the air and soil. While millions of fungal species exist, only a small number are known to cause disease in humans. While most are harmless, certain fungi can cause infections if they enter the body through inhalation or skin breaks. These infections range from minor irritations to life-threatening conditions.
Classifications of Fungal Infections
Fungal infections are broadly categorized based on the location and depth of tissue they affect. The most common types are superficial mycoses, which are limited to the outermost layers of the skin, hair, and nails. Examples include athlete’s foot (tinea pedis), jock itch (tinea cruris), and various forms of ringworm (tinea corporis). These infections are not severe but can cause discomfort through symptoms like itching, redness, and peeling skin.
A second category, subcutaneous mycoses, involves the deeper layers of the skin, such as the dermis and subcutaneous tissues. These infections often occur when fungi from soil or decaying vegetation enter the skin through a cut or wound. Conditions like sporotrichosis and chromoblastomycosis fall into this group and can present as lumps or persistent skin lesions.
The most serious category is systemic, or invasive, mycoses, which affect internal organs and can spread throughout the body. These infections usually originate in the lungs after spores are inhaled and can then disseminate to other organ systems. Examples include histoplasmosis, invasive aspergillosis, and cryptococcosis.
Common Fungal Pathogens and Their Sources
Dermatophytes are a prevalent group of fungi that feed on keratin, a protein in the skin, hair, and nails. They cause infections like ringworm and athlete’s foot and are spread through direct contact with an infected person, animal, or contaminated surfaces.
Candida is a yeast normally found on the skin and in the mouth and digestive tract. Its growth is kept in check by other microorganisms, but certain conditions can disrupt this balance. This allows Candida to overgrow and cause opportunistic infections like oral thrush and vaginal yeast infections.
Another significant fungal pathogen is Aspergillus, a common mold found in soil, decaying vegetation, and household dust. Humans are constantly exposed to Aspergillus spores through inhalation, though it rarely causes illness in healthy individuals. Inhaling these spores can lead to a serious lung infection known as aspergillosis, which can become invasive.
Factors Increasing Susceptibility
Certain factors can significantly increase a person’s vulnerability to fungal infections by weakening the body’s natural defenses. A primary risk factor is a compromised immune system. This can be due to medical conditions like HIV/AIDS, certain cancers, or the use of immunosuppressant drugs following an organ transplant.
The use of broad-spectrum antibiotics can also raise the risk of fungal infections. These medications can disrupt the natural balance of microorganisms in the body, particularly in the digestive tract and vagina. By killing off beneficial bacteria that normally compete with fungi for resources, antibiotics can create an environment where fungi like Candida can multiply without restraint, leading to an opportunistic infection.
Certain pre-existing health conditions are also associated with a higher risk. Uncontrolled diabetes, for instance, can lead to higher sugar levels in the body, which can promote fungal growth, and it may also impair immune function and circulation. Hospitalization also increases risk, as invasive medical devices like catheters can introduce fungi into the body while a person’s overall health is weakened.
Medical Diagnosis and Treatment
Diagnosing a fungal infection begins with a thorough evaluation by a healthcare provider, which often includes a physical examination of the affected area. For skin-related infections, the appearance of a rash or lesion can provide initial clues. To confirm the presence of a fungus, a doctor may take a sample, such as a skin scraping, a nail clipping, a blood sample, or a tissue biopsy. This sample is then analyzed in a laboratory, either by direct microscopic examination to look for fungal elements or by placing it in a culture to grow the fungus for identification.
Once a fungal infection is diagnosed, treatment is tailored based on the type of fungus and the severity and location of the infection. For superficial infections affecting the skin or nails, treatment often involves topical antifungal medications, which are applied directly to the affected area as creams, ointments, or powders. These are available both over-the-counter and by prescription.
For more persistent or widespread infections, oral antifungal medications may be prescribed. These pills work systemically to fight the infection from within. In cases of severe, systemic fungal diseases that affect internal organs, the most aggressive treatment is required. This often involves the administration of powerful antifungal drugs intravenously (IV) in a hospital setting. The duration of treatment for serious infections can last for several months to ensure the fungus is completely eradicated.