December 2002: 19-year old male with febrile illness after jet ski accident

The December 2002 COM. A 19-year-old healthy male fell into stagnant water of the intercostal waterway (salt water of South Florida), following a jet ski accident. He sustained minor superficial injuries but engulfed significant quantities of water and sediment. A few days later he developed bifrontal headaches, vomiting, a stiff neck and a temperature of 102 degrees F. A CT scan on admission without contrast was negative. The CSF had markedly elevated white count but bacterial and fungal cultures were negative. He became progressively lethargic. On the fifth day he developed seizure activity. He expired the next day despite antibiotics. Gross examination of the brain at autopsy revealed edema, cerebellar tonsillar herniation and purulent meningitis. Microscopic examination revealed a massive leptomeningeal inflammatory infiltrate composed of neutrophils, lymphocytes, and numerous histiocyte-like cells. The inflammatory infiltrate extended into the cerebral parenchyma in numerous areas also involving the cerebellum, brainstem and ventricular system. Given the exposure to stagnant water (later confirmed to be a man-made fresh water lake), and the numerous histiocytic-like cells, suspicion for an amebic etiology of the disease process was raised and the CDC identified the ameba as Naegleria Fowleri. Infection by Naegleria Fowleri, a free-living ameba, occurs after exposure to polluted water in man-made fresh water lakes, ponds, swimming pools, particularly during the warm weather months when the thermophilic ameba grows well. The pathologic substrate of the infection is an acute hemorrhagic, necrotizing meningo-encephalitis mainly at the base of the brain, brainstem and cerebellum occurring in young, healthy individuals.