Molecular characterization and phylogenetic analysis of Fasciola gigantica from western Java, Indonesia.

Fasciola gigantica and aspermic (hybrid) Fasciola flukes are thought to be distributed in Southeast Asian countries. The objectives of this study were to investigate the distribution of these flukes from unidentified ruminants in western Java, Indonesia, and to determine their distribution history into the area. Sixty Fasciola flukes from western Java were identified as F. gigantica based on the nucleotide sequences of the nuclear phosphoenolpyruvate carboxykinase (pepck) and DNA polymerase delta (pold) genes. The flukes were then analyzed phylogenetically based on the nucleotide sequence of the mitochondrial NADH dehydrogenase subunit 1 (nad1) gene, together with Fasciola flukes from other Asian countries. All but one F. gigantica fluke were classified in F. gigantica haplogroup C, which mainly contains nad1 haplotypes detected in flukes from Thailand, Vietnam, and China. A population genetic analysis suggested that haplogroup C spread from Thailand to the neighboring countries including Indonesia together with domestic ruminants, such as the swamp buffalo, Bubalus bubalis. The swamp buffalo is one of the important definitive hosts of Fasciola flukes in Indonesia, and is considered to have been domesticated in the north of Thailand. The remaining one fluke displayed a novel nad1 haplotype that has never been detected in the reference countries. Therefore, the origin of the fluke could not be established. No hybrid Fasciola flukes were detected in this study, in contrast to neighboring Asian countries.