**Core Concept**
Acute Primary Amoebic meningoencephalitis (PAM) is a rare but often fatal disease caused by the protozoan Naegleria fowleri. This amoeba infects humans through contaminated water, leading to inflammation of the brain (meningoencephalitis). The infection is characterized by the amoeba's ability to invade the central nervous system (CNS) via the olfactory nerve.

**Why the Correct Answer is Right**
Naegleria fowleri infects humans when contaminated water enters the nasal cavity, allowing the amoeba to migrate through the olfactory nerve to the CNS. Once inside, the amoeba causes inflammation and damage to brain tissue, leading to severe symptoms such as headache, fever, and seizures. The infection is usually fatal if not treated promptly with antiparasitic medication, such as miltefosine or eflornithine.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not provide any relevant information about the cause or symptoms of PAM.
**Option B:** This option is incorrect because it is not a recognized treatment for PAM.
**Option C:** This option is incorrect because it does not accurately describe the route of infection for Naegleria fowleri.

**Clinical Pearl / High-Yield Fact**
Naegleria fowleri can infect humans through contaminated water in swimming holes, hot springs, or other warm bodies of water. Individuals who engage in water-related activities during peak summer months are at higher risk of contracting PAM.

**Correct Answer: C. The infection is usually fatal if not treated promptly with antiparasitic medication, such as miltefosine or eflornithine.