Our son Sean, is 3 and a half years old. He has what you call impetigo. One person I told about this said it was a third world nation childhood disease that came from unhealthy or dirty living conditions. Well I don't have a dirty son, and I don't live in a third world nation, and my son is not unhealthy (besides this annoying impetigo)! My husband tells me that he had it as a little guy himself. Elocon and Bactroban really don't help. I am very curious about this disease. Exactly what is it? How did he get it, and how can we avoid getting it in the future? Is it contagious? Anything you can tell me about this would be greatly appreciated.

In those last precious moments that Sean was inside you, before labor began, his skin was pure and unspoiled, untouched by any bacteria, protected by your womb. As he entered this world, his skin picked up organisms from your birth canal. Over the next week, these hitchhikers gradually multiplied. Within 10 days, their descendants covered every nook and cranny of Sean's skin.

By and large, these quiet bacteria make good neighbors. Sean and the bacteria peacefully coexist, and the stable colonies of bacteria even help keep down the population of more aggressive intruders.

Healthy skin is remarkably resistant to infection. It is a powerful barrier, keeping the billions of bacteria outside and Sean on the inside. The outer layer, called the stratum corneum or horny layer, is a thin, flexible coat of armor made of the same material as a rhinoceros's horn. The stratum corneum is constantly growing and shedding, moving bacteria outwards. The moving barrier is only completely effective when the skin is dry.

This thin armor can be breached by insect bites, by minor cuts and scrapes, by patches of eczema, or by chronically wet skin from hot muggy weather or hot clothes (diapers). Areas of skin that are red and inflamed, perhaps from rubbing, from a runny nose or from drool, have a disrupted stratum corneum.

When bacteria enter the skin through a chink in this armor, an infection can result. Some people are more susceptible to skin infections than others. This genetic susceptibility runs in families.

The two major types of bacterial skin infections are folliculitis and impetigo. Folliculitis is an infection of the hair follicles. Impetigo is a superficial infection of the skin itself. Impetigo usually begins with flat, red, 1-2 mm lesions, which quickly rise to little blisters or pustules, and eventually to open sores, often with a soft yellow-brown scab. These lesions can spread locally or under the skin and pop up at distant sites.

Each lesion is teeming with aggressive bacteria, but the bacteria cannot enter intact, healthy skin. Each time Sean touches the impetigo and then scratches another part of the skin with that finger, he can start a new spot of impetigo. (It is wise to keep his nails trimmed and to wash his hands often with an antibacterial soap). Others can catch impetigo from him if the bacteria come in contact with a break in their stratum corneum.

Two types of bacteria are the main culprits: staphylococcus (staph) and streptococcus (strep). Gentle washing with a bactericidal cleanser can help prevent local spread and reoccurrence, but antibiotics are the mainstay of therapy.

Topical antibiotic ointments are very effective for staph impetigo (which is more commonly seen around the nose and on the trunk or arms). Bactroban ointment is the most effective topical antibiotic. It can also work for strep impetigo (more commonly seen on the legs, in the diaper area, and on hot, moist skin), but failures and relapses are more common. Bacteria live under the yellow-brown scabs.