Medics identified a black worm — which was 38 millimeters (1.5 inches) long and still moving — inside the woman’s left tonsil, and removed the creature using tweezers.
DNA testing on the worm identified it as a fourth-stage larva of “Pseudoterranova azaras,” a parasitic roundworm, the study, published in July, revealed.
The parasite infects the stomach after a host has consumed larvae in raw or undercooked marine fish, the study said, with more than 700 cases reported in Japan, North Pacific countries, South America, and the Netherlands.
The woman’s blood test results were normal, and her symptoms rapidly improved after the worm was removed, the journal noted.
Medics and scientists have documented similar infections in patients who consumed seafood dishes.
In one particular case, a previously healthy 32-year-old man was found to have a swollen intestinal membrane with a firmly attached parasite — its end penetrating the stomach — which was discovered after the patient suffered severe upper gut pain, vomiting and a week-long fever. During an interview, the man said he had recently eaten sushi.