Your skin helps protect you from germs, but occasionally those germs can infect the skin. Some common types of skin infections are bacterial, fungal, viral and parasitic.
There are a number of types of bacteria that can cause skin infection. A common infection is impetigo, caused by staph or strep germs and generally more common among children than adults. Folliculitis, an inflammation or infection of the hair follicles, can appear as small whitehead pimples on your head or around hair follicles anywhere on the body. Larger, cystic lesions are called boils. Eruptions caused by bacteria are often pustular (bumps topped by pus) or may be plaque-like and quite painful (cellulitis). Poor hygiene plays little or no role.
We have many types of fungi that normally live on our skin all the time. While most cause no problems, sometimes a fungus can cause an infection. Similarly, yeasts are botanically related to fungi and may also cause skin rashes. Fungal infections present as a scaly rash and include tinea versicolor, most often seen in the upper torso, neck and arms; athlete’s foot, most often seen between the toes; jock itch, seen on the skin of the groin; ringworm, seen on the skin of the body or in particular, on the scalp or beard area; and fungal nails. Intertrigo is a yeast infection found in skin folds, most often the armpits, groin, and under heavy breasts or fat folds. Yeast infections look fiery red and have pustules around the edges. Fungus and yeast infections have little to do with hygiene. Despite their reputation, fungal rashes are not commonly caught from dogs or other animals, nor are they easily transmitted in gyms, showers, pools, or locker rooms.
Most human skin parasites bite and leave but some may stay for an extended period. Parasites will cause itching and present as a rash or red scaly skin. Weeping eczema and other skin reactions are also common skin reactions when the body is trying to flush out a parasitic infection. Left untreated, certain skin parasites can cause infection and scarring. Human skin parasites include lice, mites, fleas, bedbugs, and scabies.
There are many viral skin infections. They range from the common to the rare, from the mild to the severe and from those causing just skin infection to those with associated systemic disease. Some viral infections include warts, herpes simplex, nonspecifical viral rash, herpes zoster, and molluscum contagiosum.
Herpes simplex viruses are categorized into two types: herpes type 1 or oral herpes; and herpes type 2 or genital herpes. Typically, herpes type 1 causes sores around the mouth and lips, sometimes called fever blisters or cold sores. With genital herpes, the infected person may have sores around the genitals, buttocks, hips or perianal region.
Herpes zoster, also known as shingles, usually appears in older adults but may be seen in younger persons. Most people who get shingles will get better and will not get it again but it can reoccur in another body area in about 10% of patients. Shingles occurs when the virus that causes chickenpox reactivates in your body. After you get better from chickenpox, the virus "sleeps" (is dormant) in your nerve roots. In some people, it stays dormant forever. In others, the virus "wakes up" when disease, stress, or aging weakens the immune system. It is not clear why this happens. Typically, after the virus becomes active again, it can only cause shingles, not chickenpox. While you will not catch shingles from someone who has shingles, there is a small chance that a person with a shingles rash can spread the virus to another person who has not had chickenpox and who has not gotten the chickenpox vaccine.
Molluscum contagiosum is commonly seen in younger patients and present as small white, pink, or flesh-colored raised bumps or growths with a dimple or pit in the center. The growths range from about the size of a pinhead to as large as a pencil eraser. They may occur anywhere on the body including the face, neck, arms, legs, abdomen, and genital area, alone or in groups. The bumps are rarely found on the palms of the hands or the soles of the feet. They are usually painless unless scratched. Molluscum may disappear within 6 to 12 months without treatment and without leaving scars; however, treatment may be needed due to its contagious nature.
Nonspecific viral rash presents as a red blotchy eruption and accompanied by the common symptoms of a viral infection like fever, headache and malaise. The rash usually develops rapidly. The appearance varies but often takes the form of a red blotchy eruption.
Warts are the most common viral infection, appearing as small growths resembling a cauliflower or a solid bump. They typically occur on the hands or feet but can grow on any part of the body. Warts are often skin-colored and feel rough, but they can be dark (brown or gray-black), flat, and smooth. The many varieties of warts are contagious and usually enter the body in an area of broken skin. They typically disappear after a few months but can last for years and can recur.