Epidemo keratoconjunctivitis is caused by?
**Core Concept**
Epidemic keratoconjunctivitis (EKC) is a highly contagious and acute viral infection of the eyes, primarily affecting the conjunctiva and cornea. It is caused by a specific adenoviral serotype that leads to inflammation and potentially severe vision impairment.
**Why the Correct Answer is Right**
The correct answer is **Adenovirus**, specifically types 8, 19, and 37, which are known to cause EKC. Adenovirus enters the eye through direct contact with an infected individual, contaminated fomites, or through airborne transmission. Once inside, the virus replicates in the conjunctival epithelial cells, leading to an intense inflammatory response and the characteristic symptoms of EKC, including redness, swelling, and discharge.
**Why Each Wrong Option is Incorrect**
* **Option A:** Herpes simplex virus (HSV) can cause ocular infections, including keratitis and conjunctivitis, but it is not the primary cause of epidemic keratoconjunctivitis.
* **Option B:** Chlamydia trachomatis is a common cause of trachoma, a chronic conjunctivitis, but it is not associated with epidemic keratoconjunctivitis.
* **Option C:** Staphylococcus aureus is a common cause of bacterial conjunctivitis, but it is not the primary cause of epidemic keratoconjunctivitis.
**Clinical Pearl / High-Yield Fact**
EKC is highly contagious and can spread rapidly through populations, particularly in crowded areas. Healthcare workers and individuals with weakened immune systems are at increased risk of developing severe EKC.
**Correct Answer: D. Adenovirus**