It is easy to get sick with opisthorchiasis - come to the focal zones of infection: Siberia, Thailand, Cambodia, etc. Eat raw fish there - congratulations, you have opisthorchiasis.
At the same time, you can get sick in other regions if fish or parasite larvae are on your table. You can’t get sick from person to person. It is believed that freezing and heat treatment helps to destroy the larvae. It is worth noting that this is true if the fish is shock-frozen, has been frozen for 21 days at a temperature of -4 and below. If freezing was another way, the larvae could die, there is no exact data. Same with cooked fish. If you fry or boil the fish for 20-40 minutes, then most of the larvae die. In practice, such heat treatment makes food tasteless, which is why so few people do it, especially in restaurants.
It should be noted that in Russia they most often say the word opisthorchiasis, worms of the order of trematodes. In addition to opisthorchs, there are clonorchs and other representatives of this order. They are all similar in symptoms and there is no guarantee that the doctor understands exactly what kind of liver flukes you have.
This is important because there is a belief that opi can only be contracted from raw carp fish. In practice, there are frequent cases that people became infected without even eating fish - for example, a cook in a restaurant did not wash the board well, or there were cases of clonorchiasis from undercooked salmon, and the doctor diagnosed opisthorchiasis. They picked up a fish, washed their hands badly - congratulations, you have opisthorchiasis.
The statistics are much worse in Asia. If in Russia there is still an understanding of hygiene and sanitation in restaurants, then in Thailand, in some provinces, the infection of the population can reach 80%.