ELIMINATION OF HAPLOCHIS TAICHUI METACERCARIA IN CYPRINOID FISH WITH FREEZING TEMPERATURE AND SOURED FISH (PLASOM) WITH SALINITY

Human Haplorchis taichui intestinal fluke infection occurs via consumption of raw or undercooked cyprinoid fish and products made of this fish, eg soured fish (plasom). This study investigated the elimination of the Haplorchis taichui metacercaria in cyprinoid fish by freezing temperature (-20°Celsius) and in plasom made From cyprinoid fish by salinity. Moving score and movability index were used as criteria for determining viability of the metacercaria. Fish samples were derived from a natural reservoir at village Phu Khambao, Tambon Uboirattana, Ubonrattana District, Khon Kaen, Thailand (GPS location: 16°43'22"N 102°37'28"E). The results showed that fish samples stored at -20°Celsius in a commercial freezing (ice-cream) cabinet must be kept for at least 72 hours to completely eliminate the metacercaria. In addition, salinity at 41.2 ppt or higher effectively eliminated the metacercaria in plasom samples kept at room temperature for two days. Since plasom with high salinity is too salty and unhealthy, households or home-based producers should be suggested to produce fluke-free plasorn by using fish stored in commercial ice-cream cabinet for 72 hours.