Fulminant Amoebic meningoencephalitis caused by –
**Core Concept**
Fulminant amoebic meningoencephalitis is a rare and rapidly progressive infection of the central nervous system caused by the protozoan parasite *Naegleria fowleri*. This condition typically affects individuals who engage in freshwater activities, such as swimming or diving, and is characterized by severe inflammation and necrosis of the brain tissue.
**Why the Correct Answer is Right**
The correct answer is *Naegleria fowleri*, which is a thermophilic amoeba that infects humans through the nasal cavity. Upon entry, the amoeba migrates to the brain via the olfactory nerve, where it causes severe inflammation and necrosis of the brain tissue. The pathogenesis involves the production of cytolytic enzymes and the disruption of the blood-brain barrier, leading to rapid progression of the disease.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because *Acanthamoeba* species cause a different type of amoebic encephalitis, which is typically seen in immunocompromised individuals.
**Option B:** This option is incorrect because *Entamoeba histolytica* causes amoebic dysentery, which is a gastrointestinal infection, not a meningoencephalitis.
**Clinical Pearl / High-Yield Fact**
It's essential to note that *Naegleria fowleri* infection is often associated with freshwater exposure, particularly in warm climates. Prompt diagnosis and treatment with antiparasitic medications, such as miltefosine, are critical in managing this condition.
**Correct Answer:** C. *Naegleria fowleri*