Although acidic conditions did not
affect metacercariae excystation (Petney et al., 2013), it may cause
metacercariae degeneration, resulting in an inability to infect the
host during this period. Moreover, other factors such as high salt concentration
may also affect metacercariae morphology and infectivity
(Kruatrachue et al., 1982). Therefore, in order to avoid liver fluke
infection, only raw pla-som that has been fermented for five days or
more should be consumed.