It's not everyone's favorite subject -- and understandably so. For most people, developing an unsightly skin fungus may be pretty embarrassing. But such infections are actually very common. For instance, it's estimated that at any one time in the United States, at least one in five people have athlete's food, a particular type of skin fungus [source: Wallace].
Still, for many, the sight of -- or mere idea of -- a fungus living in one's skin is repulsive. But if you can distance yourself from the disgust, fungus is actually pretty fascinating. Once thought to be plants (mushrooms are still sorted among vegetables in the supermarket, after all), fungi's distinct cell walls and lack of chlorophyll distinguish them today as their own kingdom consisting of at least 80,000 species.
Most of the types of fungus we'll discuss are molds known as dermatophytes. These dermatophytes like to set up camp on skin because they feast on keratin, a strong, fibrous protein that makes up much of your skin (as well as nails and hair, where fungus can also thrive).
One of the most important things to keep in mind is that, besides keratin, fungus loves two things: warmth and moisture. This is why it so often holes up on sweaty feet. Skin fungus is contagious and can spread most commonly among people, but you can also get it from animals and clothes and fabrics (and even soil).
We'll go through some of the common types of skin fungus and also look at signs of getting them and how to treat them.
Jock itch, or tinea cruris to the scientific community, is probably the most uncomfortable skin fungus. And keep in mind that although it typically affects males, women can get it, too.
This type of skin fungus is characterized by a rash developing around the groin, anus and inner thighs (however, the penis and scrotum are not usually affected). The center of the rash can get reddish-brown, while the edges develop scales or bumps. The skin gets scaly and will burn and itch. It may even develop blisters that ooze.
It's not uncommon for a person to develop jock itch after getting athlete's foot (which we'll talk about later). This could have to do with a fungus spreading by the process of putting on underwear -- so it's probably a good idea to put socks on first.
Typical treatments include topical creams, usually with one of two types of anti-fungal ingredients: allylamines or azoles. Allylamines will work faster, but are typically more expensive than azoles [source: Mayo Clinic].
Tinea corporis is a skin fungus that forms on the body's trunk or extremities. This type is more likely to affect women than men, as opposed to jock itch or athlete's foot, which are both more common in men.
A person can get tinea corporis from other people, animals such as cats and dogs, or even objects such as clothes or towels. Acute tinea corporis starts and spreads quickly to develop red pustular lesions and patches. On the other hand, chronic tinea corporis can look quite different -- spreading slowly and developing less severe rashes.
Tinea corporis is also known as ringworm of the body. It's important to note that although skin fungus can be called "ringworm," it has nothing to do with a literal parasitic worm. Rather, it simply refers to the ring shape that the rashes form.
As with the previously discussed fungi and fungal infections, anti-fungal creams and ointments are commonly used to treat tinea corporis, as are oral medications.
Tinea versicolor affects the upper body -- usually the chest and back, but sometimes the neck and upper arms. You'll notice that most of the fungal types covered here will use the word "tinea" because this refers to dermatophytes. Although there are many species of fungi that fall under the category of dermatophytes, a single species can affect different parts of the body and cause different skin reactions.
Tinea versicolor is particularly marked by a discoloration of the skin. This is because it causes small spots on the skin that form into patches. These patches can make the skin either lighter or darker, and they can appear white, brown, tan or pink. You can't tan these patches away because the fungus prevents them from tanning with the rest of your skin [source: Mayo Clinic].
This kind of fungus latches on to oily parts of the upper body and can make the skin flake and itch. If over-the-counter anti-fungal lotions don't work, go to the doctor. Treatment may include prescription-strength anti-fungal lotion or cream, or the doctor may even prescribe taking pills with one of the following ingredients: ketoconazole, itraconazole or fluconazole.
But don't expect a miracle overnight cure. It may take quite some time -- weeks or months -- for tinea versicolor to clear up completely.
Next, we'll talk about a non-tinea type of skin fungus.
Candida yeasts usually reside in the mouth, digestive tract or vagina, but it can overgrow on or inside the body to develop into an infection. Sometimes people taking antibiotics for a bacterial infection may develop candidiasis, because the medication can kill off bacteria that usually keep candida from overgrowing [source: Merck].
Moist areas on the body, such as armpits, in between toes, under women's breasts, the anus and the groin are all susceptible to candidiasis. Unlike with jock itch, candida infections often spread to the penis itself -- more commonly in men who are uncircumcised. Obesity is also a contributing factor for candida skin infections, because body folds provide more hospitable areas for the fungus to grow. Incidentally, aside from exterior skin, candida can also infect the lining of the mouth or vagina (commonly referred to simply as a yeast infection).
Several different species of candida yeast can cause these infections, and they may look different depending on where they are on the body. They often result in reddish, rashes with pustular bumps and lesions. Not surprisingly, on the feet, it can resemble athlete's foot. The affected skin will also likely scale and fissure.
As with dermatophyte infections, you can fight candidiasis with anti-fungal creams. If over-the-counter topical agents don't work, seek out a doctor, who might prescribe something stronger.
Tinea pedis, or athlete's foot as it's popularly known, is the most common form of skin fungus. So, it's nothing to be embarrassed about; if you have it, you are far from alone. As mentioned in the first section, as many as 20 percent of people in the United States may this at any one time [source: Wallace].
As the popular name suggests, it commonly afflicts people who exercise in athletic shoes (which make the feet warm and moist from perspiration) and who frequent public locker rooms and swimming pools, where the fungus can spread.
Appearance-wise. athlete's foot can take on a few different guises. It could cause scales or fissures to form in between toes. Or, it can also affect other areas of the foot, causing blisters and other kinds of skin lesions on the heels, soles or along the sides. In addition to peeling and cracking skin, it usually causes burning and itching.
You can treat athlete's foot with an over-the-counter or prescription-strength topical anti-fungal cream, or with a pill including one of the following ingredients: itraconazole, fluconazole or terbinafine [source: Mayo Clinic].
Unfortunately, recurrence is quite common, even after prolonged treatment. To prevent athlete's foot, it's always wise to practice good hygiene, change socks often and avoid direct contact with communal locker-room floors.
Read on to the next page to learn more about skin fungi and other skin conditions.
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