- Foodborne parasites can be transmitted to humans when they consume raw or undercooked fish
- These parasites tend to cause stomach infections
- But in an extraordinary case, a worm lodged itself in a woman's tonsil
When you wake up with a sore throat, it's usually a cold, an allergy, the seasonal flu, or even Covid-19.
A 25-year old woman’s sore throat, however, turned out to be something completely different, according to a case report published on 8 July 2020 in The American Journal of Tropical Medicine and Hygiene.
Worm in left tonsil
When the Japanese woman went to the doctor after experiencing a scratchy, painful throat for five days, a physical examination revealed a black, 38mm worm wriggling around in her left tonsil.
The worm was identified as Pseudoterranova azarasi (a parasitic roundworm that tends to infect marine mammals such as seals and walruses) – it had already developed to a fourth-stage larva and was shedding its skin.
Blood tests revealed that there were no other conditions that could be attributed to the parasite, and the woman’s sore throat quickly healed after the intruder was removed with a pair of tweezers.
The parasite most likely lodged itself in the woman’s tonsil after entering the body in a piece of sashimi, a type of sushi. As the parasite is most commonly found in marine mammals, it’s likely that this type of parasite can enter the human body when raw fish is consumed. The parasite would then also more likely present in the stomach and not the throat.
This parasite is related to a common parasitic roundworm called Anisakis simplex, which is known to cause stomach infections.
How likely are you to get a parasite from your sushi?
If you enjoy the odd bite of raw fish, you might want to stop reading, but a recent study from the University of Washington found a dramatic increase in the likelihood of worms being transmitted to humans when they consume raw or undercooked seafood.
According to the study, the abundance of these critters increased 283-fold since the 1970s, increasing the risk of stomach infection. This infection is known as anisakiasis and is rarely diagnosed, as worms are hard to screen and the symptoms mimic food poisoning.
It should, however, be noted that a parasite getting lodged inside a tonsil is an extremely rare occurrence.
Don't let this put you off sushi
According to corresponding author Chelsea Wood, an assistant professor in the UW School of Aquatic and Fishery Sciences, seafood processors and sushi chefs are well-practiced at spotting these worms and removing them during the preparation phase, as they can be up to 2cm long.
It is recommended that you only enjoy sushi from a reputable restaurant. Wood also recommends that you cut a piece of sashimi in half to look for any nasties before eating it.
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