**Post Exposure Immunization**

**Core Concept**
Post exposure immunization refers to the administration of vaccines after potential exposure to infectious agents to prevent the development of disease. This strategy is particularly crucial for diseases that are highly contagious and have a high mortality rate.

**Why the Correct Answer is Right**
Post exposure immunization is essential for diseases like rabies, where the incubation period can range from a few days to several months. The administration of rabies immunoglobulin and the rabies vaccine within 48-72 hours of exposure can significantly reduce the risk of rabies. This is because the rabies virus attacks the nervous system, and prompt intervention can prevent the virus from replicating and causing severe neurological damage.

**Why Each Wrong Option is Incorrect**
**Option A:** Measles immunization is typically administered to prevent the disease before exposure, not after. Measles is a highly contagious disease, but post exposure immunization is not a standard practice.
**Option B:** Polio immunization is also administered before exposure to prevent the disease. While there are post exposure treatments for polio, such as oral poliovirus vaccine (OPV), the primary strategy is vaccination before exposure.
**Option C:** Chicken pox is a self-limiting disease, and post exposure immunization is not a standard practice. While there is a vaccine available for chicken pox, it is primarily used to prevent the disease in high-risk individuals, such as those with weakened immune systems.

**Clinical Pearl / High-Yield Fact**
Remember that post exposure immunization is a critical strategy for preventing rabies, which is almost always fatal if left untreated. The key to successful post exposure immunization is prompt intervention, typically within 48-72 hours of exposure.

**Correct Answer: C. Rabies**