Primary amoebic meningoencephalitis: fifteen years later.

Primary amoebic meningoencephalitis is a fulminant and rapidly fatal diseases which principally affects children and young adults. The causative organism is Naegleria fowleri, an amoebo-flagellate found in most soil and freshwater habitats. The portal of entry is the nasopharynx from which the amoeba makes its way into the brain by penetration of the olfactory mucosa and cribriform plate. Diagnosis should be suspected in all cases of purulent meningitis and meningoencephalitis in which bacteria are not evident in the cerebrospinal fluid. Diagnosis can be made by microscopic examination of a fresh specimen of cerebrospinal fluid, or a specimen strained with Wright's or Gram's stain. Combination chemotherapy with amphotericin B and tetracycline, or amphotericin B and rifamycin, by intravenous, intrathecal, and when possible, intraventricular instillation, may offer some hope of success. Preventive measures include constant surveillance of domestic water supplies and swimming pools for amoebic contamination, and education of the public to avoid swimming in contaminated areas.