 [ Symptoms ] my child has had low grade fever and lethargy for 3 weeks what could it be  she has already had two different courses of antibiotics for a possible sinus infection [ Disease ] most helpful answer yes you can get infected with certain types of ‘worms by eating raw or improperly cooked smoked marinated or salted fish these worms can be found in herring mackerel north american salmon cod halibut rockfish sardines and squid after eating improperly prepared fish these worms invade the intestinal wall or lining of the stomach an infection in humans can cause stomach pain nausea and sometimes vomiting and diarrhea within a few hours of eating fish freezing fish at  20c  4f for at least five days kills the ‘worm and makes sushi safe for eating