Most serious complication of measles is-
**Core Concept**
Measles is a highly contagious viral infection caused by the measles virus, leading to a range of complications due to the immune system's response and the virus's effects on the body. The measles virus primarily affects the respiratory system, but its complications can be severe and life-threatening.
**Why the Correct Answer is Right**
The most serious complication of measles is subacute sclerosing panencephalitis (SSPE), a rare but fatal neurological disease that occurs years after the initial measles infection. SSPE is caused by the measles virus persisting in the brain, leading to inflammation and damage to the central nervous system. This condition is characterized by progressive inflammation, demyelination, and neuronal loss, ultimately resulting in death.
**Why Each Wrong Option is Incorrect**
**Option A:** Bronchopneumonia is a common complication of measles, but it is not the most serious complication. While pneumonia can be severe, SSPE is a more rare but devastating outcome.
**Option B:** Encephalitis is a complication of measles, but it is not as rare or as severe as SSPE. Encephalitis can occur during the acute phase of the disease, whereas SSPE develops years later.
**Option C:** Keratomalacia is a complication of measles that affects the eyes, leading to blindness. While it is a serious complication, it is not as life-threatening as SSPE.
**Clinical Pearl / High-Yield Fact**
Measles can have long-term effects on the body, and its complications can occur years after the initial infection. This is a classic example of a vaccine-preventable disease, and vaccination is crucial to prevent SSPE and other measles complications.
**Correct Answer: D. Subacute sclerosing panencephalitis (SSPE).**