**Question:** Which of the following causes orchitis without epididymitis: March 2009

**Core Concept:** Orchitis is inflammation of the testicle, while epididymitis is inflammation of the epididymis, a coiled tube in the scrotum that stores and transports sperm. Understanding the distinction between these two conditions is essential for accurate diagnosis and treatment planning.

**Why the Correct Answer is Right:**
The correct answer is **C:** Mumps, as it is a viral infection primarily caused by the mumps virus. Mumps primarily affects the testicles, leading to orchitis, without causing significant epididymitis. The infection primarily involves the seminiferous tubules in the testes, causing inflammation and swelling of the testicles.

**Why Each Wrong Option is Incorrect:**
A. **Option D (Meningococcal infection)**: Meningococcal infection primarily affects the meninges and blood vessels, causing meningitis and sepsis, not orchitis without epididymitis.
B. **Option A (Bacterial sexually transmitted infections)**: Although some STIs can cause orchitis, they typically involve the epididymis as well, leading to epididymitis.
C. **Option C (Mumps)**: As mentioned above, mumps primarily affects the testicles, causing orchitis without significant epididymitis.

**Why Each Wrong Option is Incorrect:**
D. **Option B (Herpes simplex virus infection)**: Herpes simplex virus infection typically causes bilateral (both sides) epididymitis and orchitis, not unilateral orchitis without epididymitis.

**Core Concept:**
Understanding the specific pathogens causing orchitis can help guide appropriate diagnostic and therapeutic decisions. In the case of mumps, it is essential to differentiate mumps orchitis from epididymitis, as mumps orchitis typically presents without significant epididymitis, making mumps the correct answer.

**Clinical Pearl:**
Mumps is a viral infection caused by the mumps virus, which is transmitted through respiratory droplets or saliva. The typical symptoms include fever, headache, and swollen salivary glands, but the disease can also present with testicular pain and swelling. In some cases, orchitis without epididymitis can be observed, which can help differentiate mumps orchitis from other causes of orchitis. Prompt diagnosis and treatment can prevent complications like epididymitis and infertility.

**Why Each Wrong Option is Incorrect:**
A. Herpes simplex virus infection: Herpes simplex virus infection typically causes bilateral epididymitis and orchitis, unlike mumps that presents with unilateral orchitis without significant epididymitis.
B. Meningococcal infection: Meningococcal infection usually causes both epididymitis and orchitis, differentiating it from mumps.
C. Bacterial sexually transmitted infections (STIs): STIs can cause orchitis and epididymitis, but the severity of epididymitis and orchitis may vary depending on the specific pathogen causing the infection