Impetigo

Impetigo is a highly contagious bacterial infection that affects the superficial layers of the skin. The name comes from the Latin word for "attack," which describes how the infection can suddenly appear. It is a very common condition that affects many people globally. In 2010, it was estimated that impetigo affected about 140 million people. This number represents roughly 2% of the entire world population. While anyone can catch it, the infection is most common in young children aged two to five.

The infection is caused by specific types of bacteria. The most frequent cause is Staphylococcus aureus. Another common cause is Streptococcus pyogenes. Both of these bacteria can lead to different versions of the disease. In many cases, the bacteria enter the body through breaks in the skin. These breaks might come from mosquito bites, eczema, or even scabies. Once the bacteria are present, they can cause various types of skin lesions. The infection spreads through direct contact with the sores or with people who carry the bacteria in their noses.

There are three distinct ways this infection presents itself on the skin. The most common is called nonbullous impetigo, which accounts for 70% of all cases. This type often begins as a red sore near the mouth or nose. The sore breaks and leaks fluid or pus, which then dries into a honey-colored scab. The second type is bullous impetigo, which makes up about 30% of cases. This version is mostly seen in children younger than two years old. It involves painless, fluid-filled blisters, also called bullae, on the arms, legs, or trunk. Finally, there is a deeper form called ecthyma. Ecthyma produces painful, pus-filled sores that turn into ulcers deep in the dermis, which is the layer of skin below the surface. These ulcers often form thick, gray-yellow scabs and may leave scars.

Medical history shows that doctors have studied impetigo for a long time. An English dermatologist named William Tilbury Fox first described and differentiated the condition around 1864. Before the discovery of modern antibiotics, doctors used an antiseptic called gentian violet to treat the infection. Today, treatment is much more advanced and depends on the severity of the case. For mild, localized cases, doctors often prescribe antibiotic creams like mupirocin or fusidic acid. In 95% of cases, a single seven-day course of antibiotics helps children recover. If the infection covers large areas of the body, doctors may prescribe oral antibiotics such as cefalexin or dicloxacillin. Some medical groups, like NICE, even suggest using a 1% hydrogen peroxide cream for certain cases to help prevent antibiotic resistance.

Prevention is a key part of managing this contagious condition. Because the bacteria spread through touch, hand washing is one of the best defenses. It is also important to keep any skin injuries, like cuts or scratches, clean and covered. People who are infected should avoid sharing clothing or linens with others. Keeping fingernails short can also help prevent a person from spreading the infection by scratching their own sores. In some high-prevalence areas, such as Fiji, special programs called Ivermectin Mass Drug Administrations are used to help prevent cases. This is particularly important in places where impetigo is a common result of scabies infections.

Understanding the scale of this issue helps show why prevention matters. Globally, impetigo affects more than 162 million children living in low- to middle-income countries. The rates are often highest in tropical climates and regions with high population densities. In the United Kingdom, children under the age of four are 2.8% more likely to contract the infection than the average. As people get older, the rate of infection generally declines. However, it is important to note that even adults remain susceptible to the bacteria. If left untreated, most people will typically recover on their own within three weeks.

While impetigo usually heals without leaving a scar, there can be serious complications. If the infection is not managed, it can lead to cellulitis, which is an infection of the deeper skin tissues. Another possible complication is poststreptococcal glomerulonephritis, which affects the kidneys. Some people may also experience recurring infections if the bacteria live in their noses. Because different conditions like herpes or scabies can look similar to impetigo, doctors sometimes use a culture to test for specific bacteria. This ensures the treatment is correct and helps manage the spread of the infection effectively.