Contagious sores on the face or upper limbs. Often seen in children, this infection, classified as impetigo, can spread rapidly upon contact. On the face, the sores tend to cluster in the region of the nostrils or mouth, though they can also occur on the neck. The upper limb can also be a site of infection, specifically, the hand and the forearm.

There are two bacterial species that cause such infections. One is Streptococcus pyogenes, and the other is Streptococcus aureus. One manifestation of this condition, non-bullous impetigo, begins as erupting blisters that leave raw, reddened patches and a brownish yellow crusty residue at the site of the eruption. Streptococcus aureus, on the other hand, causes bullous impetigo, which forms large blisters that do not burst. This condition tends to last longer as well.