Impetigo: Symptoms and treatment
What is impetigo?
Impetigo is a highly contagious bacterial skin infection. It can appear anywhere on the body but usually attacks exposed areas. Children tend to get it on the face, especially around the nose and mouth, and sometimes on the arms or legs.
Around 3% of children in the UK up to four years old, and 2% of children who are between five to 14 get impetigo each year, according to the NHS.
The infected areas appear in patches ranging from the size of a 5p coin to a 50p piece, starting as tiny blisters that break and expose moist, red skin. After a few days the infected area is covered with a grainy, golden crust that gradually spreads at the edges.
The most common cause of impetigo is Staphylococcus aureus. However, another bacterial cause is the group A streptococcus. These bacteria lurk everywhere. It is easier for a child with an open wound or fresh scratch to contract impetigo. Other skin-related problems, such as eczema, body lice, insect bites, fungal or bacterial infections, and various forms of dermatitis can make a person susceptible to impetigo.
Most people get this highly infectious disease through physical contact with someone who has it, or from sharing the same clothes, bedding, towels, or other objects. The very nature of childhood, which includes much physical contact and large-group activities, makes children the primary victims and carriers of impetigo.
In extreme cases, the infection invades a deeper layer of skin and develops into ecthyma, a deeper form of the disease. Ecthyma forms small, pus-filled ulcers with a crust much darker and thicker than that of ordinary impetigo. Ecthyma can be very itchy, and scratching the irritated area spreads the infection quickly. Left untreated, the ulcers may cause permanent scars and pigment changes. The gravest potential complication of impetigo is post-streptococcal glomerulonephritis, a severe kidney disease that occurs following a streptococcal infection in about 2% to 5% of cases, mainly in children.
What are the symptoms of impetigo?
- A small patch of blisters that after a few hours break into red, moist areas that ooze or weep fluid; appears mainly on the face, but also on exposed areas of the arms and legs.
- In a few days, the formation of a golden or dark-yellow crust resembling grains of brown sugar occurs. The infection may continue to spread at the edges of the affected area or affect other skin areas.
Seek medical advice if:
You have sores or a rash that worsens or becomes more uncomfortable. Impetigo needs prompt medical attention, especially if accompanied by any of the following:
- Small, very itchy, pus-filled ulcers form, with a dark brown crust. This indicates ecthyma, an ulcerated form of impetigo that penetrates deep into the skin. If left untreated, it may cause scarring and permanent changes in pigmentation.
- Urine changes, body swelling, nausea, or headache develop. These could be signs of glomerulonephritis, a kidney disease caused by bacterial toxins.
Sores associated with impetigo may be mistaken for herpes, a viral infection. Impetigo spreads faster, never develops inside the mouth, and is rarely confined to one area of the body. If in doubt, seek medical advice for an accurate diagnosis.