Naegleria fowleri from a canal draining cooling water from a factory.

In 1968, a canal draining cooling water from a factory was found to be the source of infection with primary amoebic meningoencephalitis (PAME) (one case). The bed of the canal lined with stone slabs was about 2 m wide, the flow rate of water was approximately 2 m/sec. Average annual water temperatures ranged from 27-30 degrees C. In culture, Naegleria fowleri was not found in the water of the canal, but it was present in scrapings off the canal walls and in its bottom sediment for a length of about 2 km starting at the site of the outlet of the water from the factory. The maximum number of amoebae in 1 liter of the sample was 800 individuals. The present paper discusses the detective efficacy of the culture methods employed, and the epidemiological bearing of the findings.