Russians bought fish for beer - and got infected with worms In the city of Pugachov, Saratov region, 19 people have already received an unpleasant surprise after eating dried fish from the chain of stores Pivzbod - parasitic worms. The test found in the fish pathogens of opisthorchiasis, a parasitic disease caused by dung flatworms. Parasites enter the body through poorly processed fish and affect the liver and biliary tract. Possible symptoms include fever, nausea, rash, muscle and joint pain.