A 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 serious complications, particularly in young children and immunocompromised individuals. The measles virus primarily affects the respiratory system, but its effects can be far-reaching, impacting multiple organ systems.
**Why the Correct Answer is Right**
The most serious complication of measles is subacute sclerosing panencephalitis (SSPE), a rare but devastating neurological disorder. SSPE occurs when the measles virus persists in the brain for years, leading to inflammation and damage to the brain tissue. This condition typically develops 7-10 years after the initial measles infection and is characterized by progressive neurological deterioration, including seizures, muscle weakness, and cognitive impairment.
**Why Each Wrong Option is Incorrect**
**Option A:** While pneumonia is a common complication of measles, it is not the most serious complication.
**Option B:** Encephalitis is a serious but less common complication of measles compared to SSPE.
**Option C:** Blindness may occur in some cases of measles due to complications such as keratitis or uveitis, but it is not the most serious complication.
**Clinical Pearl / High-Yield Fact**
Measles vaccination is crucial in preventing SSPE and other serious complications. Two doses of the measles, mumps, and rubella (MMR) vaccine are recommended, with the second dose administered 4-6 weeks after the first dose.
**Correct Answer: D. Subacute sclerosing panencephalitis (SSPE)**