The epidemiology and control of primary amoebic meningoencephalitis with particular reference to South Australia

Abstract

This paper reviews the history, epidemiology and control of primary amoebic meningoencephalitis (PAM), caused by Naegleria fowleri, with particular reference to South Australia. The intention has been to outline misconceptions and uncertainties pervading the earlier literature. Although PAM infections elsewhere have been attributed to cysts in air-borne dust, we believe that contact with water in the domestic environment was not adequately considered as a potential source of these infections. Several reports have cast doubt on the effectiveness of chlorine in controlling N. fowleri, although there is laboratory and South Australian field experience to the contrary. These reports can be traced to a misunderstanding of the circumstances surrounding cases of PAM reported by other workers. Provided that a continuous free chlorine residual of 0.5 mg/l can be maintained in water accessible to N. fowleri, the risk of disease should be negligible. The failure of amphotericin B therapy to save recent victims of the disease, despite relatively prompt intervention, is disappointing. Possible reasons for this, and the reports that rifampin or tetracycline combined with amphotericin might be more successful, are discussed.