Some organisms, called fungi, may cause diseases in humans. When a fungus's tiny reproductive cells (spores) enter the body or come into contact with the skin and begin to multiply, it is called a fungal infection.
Fungi may be found in virtually every type of habitat including land, fresh water, and salt water. However, they are most common in dark, moist, and warm environments. They are often found in the soil, on food, and on the skin.
Most types of fungi are harmless to humans.
Disease-causing fungi may enter the body through the skin, nose, vagina, nails, or mouth. This is because these areas of the body are the most likely to be exposed to fungi.
Fungi cause different diseases depending on the specific type of fungus and where they are in the body. Examples of common fungal infections include athlete's foot, candidiasis, histoplasmosis, jock itch (tinea cruris), onychomycosis, fungal paronychia, tinea capitis, and tinea versicolor.
Most fungal infections do not cause serious medical problems. If left untreated, some types of fungal infections may spread to other parts of the body and even lead to death. However, if diagnosed and treated quickly, most patients with fungal infections experience a complete recovery. Fungal infections are treated with medications called antifungals. Depending on the type, severity, and location of the infection, as well as the patient's overall health, antifungals may be taken by mouth, applied to the skin, or injected into the vein.
Antifungal, athlete's foot, Candida albicans, dermatophytes, fingernail infection, fungal infection, fungal nail infection, fungal scalp infection, fungal spores, fungi, fungus, histoplasmosis, jock itch, molluscum contagiosum, mucocutaneous candidiasis, nail infections, onychomycosis, oral candidiasis, oral thrush, paronychia, thrush, tinea capitis, tinea cruris, tinea pedis, tinea versicolor, toenail infection, yeast infection.
common types and causes of fungal infections
Athlete's foot (tinea pedis): Athlete's foot (tinea pedis) is a fungal infection of the foot that causes itching, stinging, and burning.
A group of fungi, called dermatophytes, cause athlete's foot. These fungi prefer warm moist environments. Individuals whose feet are exposed to this type of environment have an increased risk of developing an infection. Patients may be exposed to the fungi when they shower barefoot in a public facility, such as a gym.
Once the fungus comes into contact with human skin, it begins to reproduce. As a result, the top layer of the skin produces more skin cells than normal. This causes the skin on the feet to become thick, scaly, and itchy.
Most cases of athlete's foot can be treated with over-the-counter (OTC) antifungal medications. More severe infections that do not respond to OTC treatment may require prescription-strength antifungals.
Candidiasis: Mucocutaneous candidiasis is an opportunistic infection caused by the fungus Candida albicans. Opportunistic infections occur in individuals who have weakened immune systems. The infection can affect the mouth (oral candidiasis or oral thrush), esophagus (esophageal candidiasis), or vagina (vulvovaginal candidiasis or yeast infection).
The Candida albicans fungus is found almost everywhere in the environment, which is why most people have small amounts of Candida albicans in their mouth and/or vagina at any given time. However, individuals with healthy immune systems are usually able to prevent the fungus from multiplying and causing an infection. In rare cases, when candidiasis affects healthy individuals, symptoms are usually minor. In contrast, immunocompromised patients, such as HIV patients or patients receiving immunosuppressants, often suffer from severe symptoms including painful lesions in the mouth that make it difficult to eat.
In addition to pathogenic bacteria in the body, antibiotics may also eliminate normal, healthy bacteria which may allow for the overgrowth of Candida. Use of oral antibiotics, especially broad spectrum antibiotics, has been associated with an increased occurrence of yeast infection. Antibiotics have also been detected in animal products such as meat, poultry, and cow's milk. In human study, significantly higher Candida albicans counts were found in the stool of patients with antibiotic-associated diarrhea (AAD).
If left untreated, oral candidiasis may progress to esophageal candidiasis, which occurs when the infection spreads to the esophagus. The esophagus is the tube that leads from the mouth to the stomach. Drugs that suppress acid production, such as H2-blockers and proton pump inhibitors, may contribute to fungal infections of the upper gastrointestinal tract and may predispose some patients to infectious Candida esophagitis.
Vaginal candidiasis (yeast infection) is common in both healthy and immunocompromised patients. Researchers estimate that about 75% of all women are likely to have at least one vaginal Candida infection during their lifetime and up to 45% experience two or more. Individuals who become pregnant, take high-estrogen birth control pills, have uncontrolled diabetes mellitus, wear tight-fitting clothes, receive antibiotic therapy, or have sexually transmitted diseases have an increased risk of developing yeast infections.
Candidiasis infections are generally treated with antifungals. Treatment generally lasts about 10 to 14 days.
Histoplasmosis: Histoplasmosis is a fungal infection of the lungs that may spread to other organs and tissues of the body.
The Histoplasma capsulatum fungus causes histoplasmosis. The fungus is commonly found in damp soil that is rich in organic material. The tiny reproductive cells of the fungus (spores) enter the body through the nose or mouth when a patient inhales or consumes contaminated food or water.
Most patients with histoplasmosis do not experience any symptoms of the disease and do not require treatment. This is because healthy individuals have strong immune systems that are able to prevent the fungi from multiplying and causing an infection.
However, patients with weakened immune systems, especially HIV patients and infants, are vulnerable to developing infections that start in the lungs and spread to other areas of the body. When the infection spreads, it is called disseminated histoplasmosis. This condition is fatal if left untreated.
Patients with underlying diseases, such as emphysema, are also vulnerable to developing a long-term infection that primarily affects the lungs. When this happens, the condition is called chronic pulmonary histoplasmosis. Patients with this type of infection require lifelong treatment with antifungals.
In some cases, otherwise healthy individuals may develop histoplasmosis infections. This may happen if the patient is exposed to large amounts of the fungus. For instance, farmers who are frequently exposed to soil or bird or bat droppings have an increased risk of developing infections.
Jock itch (tinea cruris): Jock itch, also called tinea cruris, is a fungal infection that affects the skin of the inner thighs, buttocks, and genitals.
Jock itch is caused by a group of fungi called dermatophytes. The fungi that cause jock itch are usually the same organisms that causes athlete's foot, tinea capitis (ringworm of the scalp), and tinea versicolor. These organisms normally live on the skin and do not cause an infection. However, when areas of the body are frequently moist, the fungi may grow uncontrollably. Although anyone can acquire the infection, it is most common in individuals who sweat a lot, such as athletes or those who are overweight. This is because a warm and sweaty environment provides an especially good habitat for fungi.
Jock itch is mildly contagious. It may spread through physical contact or after using shared items (e.g. towels) that came into contact with the infected person's skin.
Jock itch is not a serious infection. It is usually treated with antifungals that are applied to the skin.
Onychomycosis: Onychomycosis is a fungal infection of the nail bed.
A group of fungi called dermatophytes are usually the cause of onychomycosis. The fungi that cause the infection prefer warm moist environments. Therefore, patients are most likely to develop onychomycosis if their nails are frequently exposed to such environments, such as sweaty socks or shower floors. Toenails are more likely to be affected than fingernails.
Onychomycosis can be successfully treated with oral antifungals.
Fungal paronychia: Fungal paronychia is a fungal skin infection that occurs near the nail beds. It causes the skin around the fingernails or toenails to become red and swollen. It may also cause pus-filled blisters to form.
Fungal paronychia is commonly caused by a group of fungi called dermatophytes. Fungal paronychia is common among patients with onychomycosis, diabetes, and those who are frequently getting their hands wet for long periods of time (e.g. swimmers). Biting the nails, hangnails, or pushing back the cuticles also increases the risk of an infection.
Patients respond well to treatment with antifungals. However, it may take several months for the infection to be completely cured.
Tinea capitis (ringworm of the scalp): Tinea capitis, also called ringworm of the scalp, is a fungal infection of the skin on the head.
Tinea capitis is caused by a group of fungi called dermatophytes. Once the disease-causing fungi come into contact with the skin, the organism begins to multiply and an infection develops. Tinea capitis is contagious, and it can spread through skin-to-skin contact. Patients may be exposed to the fungi after touching an infected animal, such as a dog, cat, ferret, rabbit, goat, or pig. Patients may also become infected after touching objects (e.g. towels, clothing, or bed linens) that an infected person or animal has been in contact with.
Tinea versicolor: Tinea versicolor is a common fungal infection of the skin that causes patches of the skin to appear lighter than normal. The infection generally worsens during hot and humid weather.
Tinea versicolor is caused by Malassezia furfur, which is normally found on the skin. Many factors, including hot and humid weather, immunosuppression, hormonal changes, excessive sweating, or oily skin, may trigger the fungi to multiply uncontrollably and cause an infection.
It may take several weeks for antifungal cream and lotions to completely eliminate the fungus from the body.