Naegleria fowleri, a free-living, thermophilic amoeba ubiquitous in the environment, causes primary amoebic meningoencephalitis (PAM), a rare but nearly always fatal disease of the central nervous system. While case reports of PAM have been documented worldwide, very few individuals have been diagnosed with PAM despite the vast number of people who have contact with fresh water where N. fowleri may be present. In the USA, 111 PAM case-patients have been prospectively diagnosed, reported, and verified by state health officials since 1962. Consistent with the literature, case reports reveal that N. fowleri infections occur primarily in previously healthy young males exposed to warm recreational waters, especially lakes and ponds, in warm-weather locations during summer months. The annual number of PAM case reports varied, but does not appear to be increasing over time. Because PAM is a rare disease, it is challenging to understand the environmental and host-specific factors associated with infection in order to develop science-based, risk reduction messages for swimmers.

To our knowledge, this is the first comprehensive clinical case series of PAM presented in the United States. PAM is a fatal illness with limited treatment success and is expanding into more northern regions. Clinicians who suspect that they have a patient with PAM should contact the US Centers for Disease Control and Prevention at 770-488-7100 (available 24 hours/day, 7 days/week) to discuss diagnostic testing and treatment options (see cdc.gov/naegleria).

Endotoxemia is an important risk factor for development of acute laminitis in horses during hospitalization for medical or surgical conditions. Early recognition of endotoxemia, or the potential for it to develop in certain disease states, and initiation of treatment directed at endotoxemia or its consequences may help prevent laminitis in horses during hospitalization.