Final answer:
Vesicles or blisters can be caused by skin infections such as impetigo, viral infections like herpes, physical damage including severe sunburn, contact with irritants or allergens leading to contact dermatitis, and immunological reactions.
Step-by-step explanation:
Vesicles, commonly known as blisters, can be caused by various conditions and incidents affecting the skin. For instance, impetigo is a skin infection that results in the formation of vesicles, pustules, and bullae, especially around the mouth and nose. These are often caused by bacteria like Staphylococcus aureus and Streptococcus pyogenes. Impetigo manifests in two forms: nonbullous and bullous. Nonbullous impetigo features vesicles that rupture leading to encrusted sores, while bullous impetigo results in larger draining lesions.
Other conditions like contact dermatitis, herpes infections (such as cold sores caused by the herpes virus and genital herpes), and physical damage (like sunburns that result in blistering and indicate damage to specific layers of the skin) also cause the development of vesicles. Contact with irritants or allergens can trigger contact dermatitis, and viruses such as HSV-1 and HSV-2 are responsible for herpes infections. In the case of excessive sun exposure, the epidermis and possibly the dermis are the affected skin layers. In addition to infections and physical causes, immunological reactions like delayed-type hypersensitivity can also lead to blister formation.