What is impetigo?
Impetigo (impetigo contagiosa) is a superficial bacterial infection most frequently observed in children 2-5 years of age, although adults may become infected. Lesions begin as papules (small bumps) and then progress to small vesicles (blisters) surrounded by redness of the skin (usually on the face near the mouth and on extremities). Vesicles become larger and leak fluid, producing a characteristic golden crust on the lesions.
There are two major types of impetigo: nonbullous (the most common type described above) and bullous impetigo, which is characterized by enlarged vesicles filled with a clear yellow fluid that becomes darkened and, when ruptured, forms a brownish crust. The patient's body (trunk) is often infected in contrast to nonbullous impetigo.
Unlike impetigo, ecthyma is a more serious infection that penetrates deeply into the skin; it produces fluid or pus-filled sores that are painful. These sores can produce ulcers in the skin. This subtype is not often seen.
Is impetigo contagious?
Impetigo is a highly contagious disease. Impetigo is easily spread from person to person by direct contact with the lesions and/or indirectly by touching items (clothing, sheets, or toys) that have been used by individuals with this skin disease. Indirect transmission is less frequent than direct person-to-person transmission. Bacteria cause impetigo; group A streptococci and staphylococci are the organisms that most frequently cause impetigo.
What does impetigo look like? What is the incubation period for impetigo?
A person infected with impetigo usually starts out with irritating, itchy blisters that can develop pus. The incubation period is about one to three days for streptococci and about four to 10 days for staphylococci. The individual may also develop local lymph node enlargement. Diagnosis of impetigo is often made clinically without special testing by the patient's history and physical examination and the appearance of the characteristic crusting lesions. However, the diagnosis can be confirmed by isolation and identification of the bacteria from the skin lesions.
Impetigo is not serious and is very treatable. Mild impetigo can be handled by gentle cleansing, removing crusts, and applying the prescription-strength antibiotic ointment mupirocin (Bactroban). Nonprescription topical antibiotic ointments (such as Neosporin) generally are not effective.
How does impetigo spread?
Impetigo is spread mainly by person-to-person contact; it is rapidly spread through direct transmission in day-care centers and schools. Less frequently, the disease may be spread indirectly by contact with sheets, clothing, or toys contaminated by infected individuals. Impetigo is mainly confined to humans. Contact sports may spread impetigo; wrestling is considered to be the most likely sport to spread it, followed by football and rugby.
How will I know when someone is cured of impetigo? How long is the contagious period for impetigo?
Some individuals can self-cure impetigo over about a two-week period. An infected individual becomes cured or noncontagious after the sores go away. However, this time span may be reduced with appropriate topical antibiotics. Some individuals may require more aggressive treatment with oral antibiotics or, in severe infections (rare), IV antibiotics. With effective antibiotics, the person is usually considered noncontagious after about 24-48 hours of treatment.
When should I contact a medical caregiver about impetigo?
Some individuals benefit from topical antibiotic treatment; if you or your child is involved in an outbreak of impetigo, you should contact your physician or your child's pediatrician. If fever develops or if the condition persists after about two to three days of treatment with no improvement, you should contact a physician. If the rash and lesions develop rapidly and become red, warm, and tender and/or red streaks develop, contact a physician urgently or go to an emergency department.
Is Impetigo Contagious?
See a picture of impetigo and other bacterial skin conditions
Baddour, Larry M. "Impetigo." UpToDate.com. June 2018.