Genetic Variation in the Free-Living Amoeba Naegleria fowleri

In this study, 30 strains of the pathogenic free-living amoeba Naegleria fowleri were investigated by using the randomly amplified polymorphic DNA (RAPD) method. The present study confirmed our previous finding that RAPD variation is not correlated with geographical origin. In particular, Mexican strains belong to the variant previously detected in Asia, Europe, and the United States. In France, surprisingly, strains from Cattenom gave RAPD patterns identical to those of the Japanese strains. In addition, all of these strains, together with an additional French strain from Chooz, exhibited similarities to South Pacific strains. The results also confirmed the presence of numerous variants in Europe, whereas only two variants were detected in the United States. The two variants found in the United States were different from the South Pacific variants. These findings do not support the previous hypothesis concerning the origin and modes of dispersal of N. fowleri.