Effect of household cleaning solutions and disinfectants on the infectivity of Opisthorchis viverrini metacercariae

Opisthorchiasis is caused by infection with Opisthorchis viverrini liver fluke. Humans are infected by ingestion of raw cyprinid fish contaminated with metacercariae. From histories of opisthorchiasis patients it has been found that most of them had consumed raw cyprinid fish salad or fermented fish dishes. However, some opisthorchiasis patients have no history of eating uncooked fish. We, therefore, focused on the possibility of disease transmission via contamination of kitchenware with metacercariae. Thus, the present study investigated the effect of common household cleaning solutions and disinfectants on the viability and infectivity of O. viverrini metacercariae. Metacercariae were divided into six treatment groups and exposed to four different cleaning solutions and disinfectants (Sunlight®, OMO®, Virkon® and Dettol®), dry condition, and 0.85% NaCl (control). O. viverrini metacercariae in each assigned group were observed for active, inactive and degraded metacercariae after exposure for 1, 10 and 30 min. The infectivity of metacercariae from each group was then assessed by hamster infection and the subsequent percentage of worm recovery. Dettol® was found to be the most effective cleaning solution: 98.66% of metacercariae were degraded, with 100% inhibition of movement (100% inactive), and 0% worm recovery. The results of the other treatments were: Virkon® (degraded 24%, inactive 82.67%, worm recovery 9.33%), dry condition (degraded 0%, inactive 100%, worm recovery 12%), Sunlight® (degraded 12%, inactive 80%, worm recovery 20%) and OMO® (degraded 5.33%, inactive 81.33%, worm recovery 25.33%). The dry condition did not cause degradation but did result in inactivation of all O. viverrini metacercariae. The present findings suggest that exposure to 4.8% Dettol® solution can kill O. viverrini metacercariae. This information may be useful when choosing kitchen cleaning products, and could contribute to the prevention of liver fluke infection.