A 9-year-old boy is brought to the emergency department because of a severe sore throat with fever and dysphagia. On physical examination, there are grayish-white papulovesicular lesions on an erythematous base that ulcerate. They are located on the soft palate, anterior pillars of the tonsils and uvula. There are no lesions on the gingiva, tongue, or lips. A clinical diagnosis of herpangina is made. Which of the following is the most likely causative organism?

**Core Concept**
Herpangina is a viral infection characterized by the appearance of grayish-white papulovesicular lesions on the tonsillar pillars, uvula, and soft palate, typically in children. The condition is caused by enteroviruses, which are a group of viruses that include coxsackieviruses, echoviruses, and enteroviruses.

**Why the Correct Answer is Right**
The most common causative organism of herpangina is Coxsackie A virus (CVA). This virus is highly contagious and spreads through fecal-oral contact, contaminated food and water, or close contact with an infected individual. The virus infects the tonsillar pillars, uvula, and soft palate, leading to the characteristic lesions. The lesions are caused by the viral replication and the subsequent inflammatory response, resulting in the formation of papulovesicular lesions that eventually ulcerate.

**Why Each Wrong Option is Incorrect**
**Option A:** Herpes simplex virus (HSV) typically causes lesions on the gingiva, tongue, or lips, which are not present in this case.
**Option B:** Influenza virus can cause a sore throat, but it does not typically cause the characteristic lesions seen in herpangina.
**Option C:** Adenovirus can cause pharyngitis, but it does not typically cause the specific lesions seen in herpangina.
**Option D:** Epstein-Barr virus (EBV) is the causative agent of infectious mononucleosis, which can cause sore throat, but it does not typically cause the characteristic lesions seen in herpangina.

**Clinical Pearl / High-Yield Fact**
Remember that herpangina is caused by enteroviruses, particularly Coxsackie A virus, and is characterized by the presence of grayish-white papulovesicular lesions on the tonsillar pillars, uvula, and soft palate.

**Correct Answer:** C. Coxsackie A virus

✓ Correct Answer: C. coxsackievirus A