Balamuthia mandrillaris: A species of free-living soil amoeba in the family Balamuthiidae, causing AMEBIASIS and a deadly form of ENCEPHALITIS in humans.Amebiasis: Infection with any of various amebae. It is an asymptomatic carrier state in most individuals, but diseases ranging from chronic, mild diarrhea to fulminant dysentery may occur.Lobosea: A class of amoeboid EUKARYOTES that forms either filiform subpseudopodia or lobopodia. Characteristics include the absence of sorocarps, sporangia, or similar fruiting bodies. Lobosea were formerly members of the phylum Sarcomastigophora, subphylum Sarcodina, under the old five kingdom paradigm.Amoebozoa: A supergroup (some say phylum) of ameboid EUKARYOTES, comprising ARCHAMOEBAE; LOBOSEA; and MYCETOZOA.Central Nervous System Protozoal Infections: Infections of the brain, spinal cord, or meninges by single celled organisms of the former subkingdom known as protozoa. The central nervous system may be the primary or secondary site of protozoal infection. These diseases may occur as OPPORTUNISTIC INFECTIONS or arise in immunocompetent hosts.Amoeba: A genus of ameboid protozoa. Characteristics include a vesicular nucleus and the formation of several lodopodia, one of which is dominant at a given time. Reproduction occurs asexually by binary fission.Encephalitis: Inflammation of the BRAIN due to infection, autoimmune processes, toxins, and other conditions. Viral infections (see ENCEPHALITIS, VIRAL) are a relatively frequent cause of this condition.Meningoencephalitis: An inflammatory process involving the brain (ENCEPHALITIS) and meninges (MENINGITIS), most often produced by pathogenic organisms which invade the central nervous system, and occasionally by toxins, autoimmune disorders, and other conditions.Naegleria fowleri: A species of parasitic protozoa having both an ameboid and flagellate stage in its life cycle. Infection with this pathogen produces PRIMARY AMEBIC MENINGOENCEPHALITIS.Amebicides: Agents which are destructive to amebae, especially the parasitic species causing AMEBIASIS in man and animal.Protozoan Infections: Infections with unicellular organisms formerly members of the subkingdom Protozoa.Trophozoites: Cells or feeding stage in the life cycle of sporozoan protozoa. In the malarial parasite, the trophozoite develops from the MEROZOITE and then splits into the SCHIZONT. Trophozoites that are left over from cell division can go on to form gametocytes.Acanthamoeba: A genus of free-living soil amoebae that produces no flagellate stage. Its organisms are pathogens for several infections in humans and have been found in the eye, bone, brain, and respiratory tract.Fatal Outcome: Death resulting from the presence of a disease in an individual, as shown by a single case report or a limited number of patients. This should be differentiated from DEATH, the physiological cessation of life and from MORTALITY, an epidemiological or statistical concept.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Pentamidine: Antiprotozoal agent effective in trypanosomiasis, leishmaniasis, and some fungal infections; used in treatment of PNEUMOCYSTIS pneumonia in HIV-infected patients. It may cause diabetes mellitus, central nervous system damage, and other toxic effects.DNA, Protozoan: Deoxyribonucleic acid that makes up the genetic material of protozoa.Opportunistic Infections: An infection caused by an organism which becomes pathogenic under certain conditions, e.g., during immunosuppression.Antibodies, Protozoan: Immunoglobulins produced in a response to PROTOZOAN ANTIGENS.Antiprotozoal Agents: Substances that are destructive to protozoans.RNA, Ribosomal, 18S: Constituent of the 40S subunit of eukaryotic ribosomes. 18S rRNA is involved in the initiation of polypeptide synthesis in eukaryotes.Granuloma: A relatively small nodular inflammatory lesion containing grouped mononuclear phagocytes, caused by infectious and noninfectious agents.