What is the most likely causative pathogen for a 12-month-old with perioral vesicular lesions and gingival ulcerations?

The presence of perioral vesicular lesions and gingival ulcerations in a 12-month-old child is strongly indicative of herpes simplex virus type 1 (HSV-1) infection. This virus is commonly associated with oral and perioral lesions, often referred to as gingivostomatitis.

In young children, HSV-1 typically presents with vesicles that rupture and form painful ulcers, primarily affecting the gums, lips, and surrounding skin. The age of the child also plays a significant role; HSV-1 is the predominant strain causing such manifestations in pediatric populations, particularly in those under 5 years of age. The lesions are typically painful and can lead to difficulty eating and drinking, which further underscores the impact of the virus.

Other options, such as Candida albicans, while capable of causing oral lesions, do not present as vesicular lesions but rather as white patches or plaques, which differ significantly in appearance and symptoms. Group A coxsackievirus, also known for causing hand, foot, and mouth disease, does result in vesicular lesions but is more commonly associated with other body parts and less likely to cause isolated perioral lesions in this age group. Herpes simplex virus type 2 is primarily linked