Impetigo

What is impetigo?

Impetigo is a bacterial infection that causes red, itchy sores with yellow scabs. It’s caused by one of two bacteria: group A Streptococcus or Staphylococcus aureus. These bacteria tend to get into breaks in the skin like cuts, insect bites or other injuries (primary impetigo), or into sores caused by existing conditions like eczema (secondary impetigo). It’s a relatively harmless condition that tends to clear up on its own after a few weeks, but treatment is usually recommended to speed up recovery and reduce the risk of spread. This typically involves topical antibiotic creams for mild cases, or oral antibiotics (tablets) for more severe or widespread cases.

Although impetigo isn’t usually serious, it’s very contagious. In rare cases it can cause complications, especially for people who have a weakened immune system. It tends to affect children more than adults, and is more common in warmer, humid climates (such as the tropics and subtropics). In milder climates such as the UK, it’s more commonly seen in the summer months.^[1]

Who gets impetigo?

Anyone can get impetigo, but it’s more common in children and people who live in hot and
humid climates. It’s also more common in crowded conditions, such as schools, nurseries and military barracks.^[2]

It’s likely more common in children due to poorer hygiene and an increased close physical contact, such as during play. There’s also a theory that it’s more common in warmer, humid climates because insect bites are more common in these regions, which can serve as a starting point for the infection.^[3]

How common is impetigo?

Because it’s highly transmissible, impetigo is a pretty common skin condition, making up around 10% of all skin conditions in children. The global prevalence of impetigo is thought to be around 11.2%, which breaks down to around 12.3% in children and 4.9% in adults. This data is contested, though, as it’s thought to be based heavily on data from developing countries, where the condition spreads more easily.^[4]

By comparison, in the UK, it’s estimated to affect 2.8% for children under four and 1.6% for children aged 5-15 every year.^[5] Other global estimates suggest that around 162 million children have impetigo at any given time.^[6]

What causes impetigo?

Impetigo is usually caused by one of two kinds of bacteria (group A Streptococcus or Staphylococcus aureus) infecting a break in your skin, but it can infect unbroken skin too. When it infects a cut, bite or other injury in your skin it’s called primary impetigo, and when it infects skin broken by an existing condition, such as eczema or head lice, it’s called secondary impetigo.

Because impetigo doesn’t normally cause any symptoms for around 4-10 days, it can be easy for you to spread it without knowing through close contact or shared fabrics like towels, flannels and clothes.

Risk factors that make it more likely for you to get impetigo include:

• skin conditions that cause breaks in the skin, such as eczema, scabies and chickenpox
• skin injuries that cause breaks in the skin, such as cuts, grazes, bites and burns
• a weakened immune system, which can be caused by certain conditions like HIV or diabetes, or certain treatments, such as chemotherapy
• living in a warm, humid climate
• poor hygiene
• crowded environments

What are the symptoms of impetigo?

There are two kinds of impetigo: bullous and non-bullous. Non-bullous is the most common type, and its symptoms usually look like this:

1. First, red sores appear (usually around the nose and mouth, but other areas of the face or limbs might be affected).
2. These sores then burst, leaving behind thick, golden crusts around 2 cm across. (The appearance of these crusts is sometimes likened to cornflakes.)
3. After the crusts dry, they leave behind a red mark that usually fades without scarring.

These sores typically aren’t painful, but they may be itchy. Other symptoms like a fever or swollen glands might occur but only in rare, severe circumstances.

Bullous impetigo first appears as fluid-filled blisters called bullae, normally around the abdomen, face and legs. These bullae tend to be around 1-2 cm across, and they can quickly spread before bursting after several days. This usually leaves a yellow crust that heals without scarring.

With bullous impetigo, sores caused may be painful as well as itchy, and swollen glands and fever are more common.

Can impetigo lead to other problems?

It’s quite rare for impetigo to lead to any other problems, but it can happen.

Some complications associated with impetigo can include:

• Cellulitis: a potentially life-threatening infection of deeper-lying skin and tissue
• Scarlet fever: a rare bacterial infection that causes a pink rash, severe sore throat, and a strawberry tongue (bright red, swollen tongue covered with white bumps, giving it a strawberry-like texture)
• Guttate psoriasis: a non-infectious skin condition that causes small, drop-shaped sores
• Septicaemia: a bacterial infection in your blood
• Staphylococcal scalded skin syndrome (SSSS): a serious skin condition that makes your skin look like it’s been scalded by boiling water
• Post-streptococcal glomerulonephritis: a condition that causes the small blood vessels in your kidneys to become infected

Impetigo doesn’t tend to leave scars, but it can happen in rare cases (especially if you scratch and pick at the sores).