A10-year-old boy with symptoms of meningitis and a history of swimming in his farm pond was brought to the hospital emergency department. examination of his csf revealed motile amoeba measuring 12 µm in diameter. the most likely parasite is:

Meningitis refers to the inflammation of the protective covering of the brain and the spinal cord called the meninges. It is due to the infection by the bacteria, virus, fungi or parasites. Pathological examination of the cerebrospinal fluid (CSF) of the brain and the spinal cord can confirm the presence of the pathogen in case of meningitis.

The boy has an history of swimming in his farm pond and the examination of his cerebrospinal fluid has revealed the presence of the amoeba. It is a case of parasitic meningitis which is also called the primary amoebic meningoencephalitis. It is an infection of the brain by a free-living, unicellular parasite called Naegleria fowleri. It is found in stagnant and warm fresh water bodies like lakes, rivers and ponds and in the non-chlorinated swimming pools. It enters the central nervous system through the nose and is a fatal disease.

Thus, the parasite is identified as Naegleria fowleri.