Human eosinophilic meningitis is most commonly caused by –
**Core Concept**
Human eosinophilic meningitis is a rare inflammatory condition characterized by an elevated number of eosinophils in the cerebrospinal fluid (CSF), often in response to parasitic infections or other foreign substances. This condition highlights the body's immune response to specific pathogens, leading to an increase in eosinophil count.
**Why the Correct Answer is Right**
The most common cause of human eosinophilic meningitis is _Angiostrongylus cantonensis_. This parasitic nematode, also known as the rat lungworm, is acquired through the ingestion of contaminated food or water. When the parasite penetrates the central nervous system, it triggers an immune response, leading to an increase in eosinophil count in the CSF. The eosinophils accumulate around the parasite, attempting to eliminate it from the body.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because while certain fungal infections can cause eosinophilic meningitis, they are not the most common cause.
* **Option B:** This option is incorrect because bacterial infections are more commonly associated with pleocytosis in the CSF, characterized by an increase in neutrophils rather than eosinophils.
* **Option C:** This option is incorrect because viral infections can cause meningitis, but they typically do not lead to eosinophilic pleocytosis.
**Clinical Pearl / High-Yield Fact**
In regions where _Angiostrongylus cantonensis_ is endemic, eosinophilic meningitis should be considered in patients presenting with headache, neck stiffness, and elevated eosinophil count in the CSF after consuming contaminated food or water.
**Correct Answer:** C.