Which of the following is false regarding measles?
**Core Concept**
Measles is a highly contagious viral disease caused by the measles virus, which affects the respiratory system and the central nervous system. The measles virus targets the immune system, specifically the reticuloendothelial system, and causes a range of symptoms including fever, cough, runny nose, and a characteristic rash.
**Why the Correct Answer is Right**
The measles virus infects the respiratory epithelial cells and the lymphoid tissues, leading to a systemic immune response. The virus replicates in the respiratory tract and spreads to the lymphoid tissues, including the tonsils, spleen, and lymph nodes. This leads to a severe immune response, characterized by the production of cytokines and the activation of immune cells.
**Why Each Wrong Option is Incorrect**
* **Option A:** This statement is true. Measles is a highly contagious disease, and the virus is spread through respiratory droplets, contact with infected bodily fluids, and contaminated surfaces.
* **Option B:** This statement is false. Measles does not cause a direct invasion of the central nervous system. While it can lead to complications such as subacute sclerosing panencephalitis (SSPE), this occurs years after the initial infection.
* **Option C:** This statement is true. Measles is a vaccine-preventable disease, and the measles, mumps, and rubella (MMR) vaccine is widely used to prevent measles infection.
* **Option D:** This statement is true. Measles causes a range of symptoms, including fever, cough, runny nose, and a characteristic rash, which typically appears 10-14 days after exposure to the virus.
**Clinical Pearl / High-Yield Fact**
Measles is a key public health concern, and vaccination is crucial in preventing outbreaks and controlling the spread of the disease. The MMR vaccine is effective in preventing measles infection and should be administered to children at 12-15 months of age and a booster dose at 4-6 years of age.
**Correct Answer: B. Measles does not cause a direct invasion of the central nervous system.**