isolation and identification of naegleria species from environmental water in changchun, northeastern china.

background: naegleria is a free-living amoeba, and pathogenic naegleria may pose a health risk to people exposed to recreational water. our objective in this study was to determine if there are pathogenic amoebae in environmental water samples from changchun, northeastern china. methods: during july to september 2012, a total of 70 water samples were collected from changchun, northeastern china, and naegleria was enriched by in vitro culture and detected by pcr using naegleria genus-specific primers. re-sulting pcr products were sequenced and phylogenetically analyzed to identify naegleria species. results: naegleria was detected in 65 (92.9%) of 70 water samples. dna se-quence and phylogenetic analyses based on the internal transcribed spacer (its) rdna sequences revealed four naegleria species, including n. pagei (n = 24) and n. australiensis (n = 18), n. clarki (n = 13) and n. gruberi (n = 10), in which n. australiensis is pathogenic to mice. but the pathogenic species n. fowleri was not detected. conclusion: this is the first report on naegleria species in northeastern china, showing that almost all environmental water samples were contaminated with naegleria , including n. pagei , n. australiensis , n. clarki and n. gruberi , which should be considered a potential public health threat.