Doctors discovered a 4cm worm in a woman's mouth after she ate a piece of raw fish.

A worm

A worm

The 25-year-old female tucked into some sashimi without noticing the parasitic roundworm.

The unnamed woman complained of having throat pain and irritation after eating the snack and went to visit a doctor, who found a ''black moving worm'' on her tonsil.

The strange case was revealed in the American Journal of Tropical Medicine and Hygiene.

Researchers wrote: ''Her blood test results were normal. Symptoms rapidly improved after removing the worm using tweezers.

''The worm body was black, 38 mm long, 1mm wide, and was moulting the outer cuticle.''

There have previously been cases of worms being found in stomachs, but it is extremely rare for it to be removed from a person's mouth.