Isolation of free-living pathogenic amoebae from thermal spas in N.W. Spain

We tested for the presence of free-living amoebae in water from 12 thermal spas in northwest Spain; 8 tested positive. No relationship was observed between temperature, pH or bacterial contamination and either the presence of amoebae or the, number of strains per sample. A total of 13 strains were found: 5 of Vahlkampfia, 2 of Naegleria, 3 of Acanthamoeba and 3 of other genera. Those Naegleria and Acanthamoeba strains which survived at 37 ? were tested for pathogenicity by intracerebral and intranasal inoculation of mice; only 2 strains (both of the species Acanthamoeba polyphaga) caused death.