Gnathostomiasis is the human infection caused by nematodes of the genus Gnathostoma. People become infected when they consume insufficiently cooked swamp eels, freshwater fishes, frogs, birds, and reptiles. The typical manifestations of Gnathostomiasis are migratory swelling and elevated levels of eosinophils in the blood.

Gnathostomiasis is caused by five species of Gnathostoma: G. spinigerum, G. binucleatum, G. hispidium, G. doloresi, and G. nipponicum. The five species are endemic in Asia, Latin America, and South and Central South Africa. Infections caused by the species G. spinigerum are common in Asia, specifically in Thailand.  G. binucleatum is common in the Americas. G. hispidium and G. doloresi commonly occur in East and Southeast Asia, but the former has been reported in eastern Europe. At the same time, cases of infection caused by G. nippocum were all from Japan and China.


Symptoms of Gnathostomiasis develop as soon as 24 hours after the ingestion of the nematode. Initial indicators of the infection are:

  • Fever
  • Epigastric pain
  • Vomiting
  • Anorexia
  • Urticaria
  • Diarrhea
  • Abdominal pain

When larvae migrate through the intestinal wall to the abdominal cavity, the infected person may experience loss of appetite.

When larvae migrate under the skin, it may cause migratory swelling that is painful and pruritic, accompanied by itch, rash, skin abscess, creeping eruptions, and stabbing pain in the swelling region/s. The swellings begin after 3-4 weeks of ingestion and can last for up to 4 weeks and reappear in a different location. The eosinophils in the body get elevated (eosinophilia) because of the swellings.

The parasitic worms can also migrate and infect the eyes, gastrointestinal tract, the pulmonary tract, the genitourinary tract, the central nervous system, liver, ear, nose, and throat. The effects of the nematode’s migration to other tissues vary, but all are serious. Gnathostomiasis can cause:

  • Subarachnoid hemorrhage
  • Encephalitis
  • Hydrocephalus
  • Meningitis
  • Hematuria
  • Eosinophilia
  • Damage to the retina
  • Irreversible blindness
  • Paralysis
  • Coma
  • other significant long-term health issues
  • Death


The primary form of diagnosis of the infection is through microscopy- identification, and examination of the tissue’s larva. Imaging tests such as CT scan and MRI can also locate the parasitic worms in the body.

If you have a recent history of eating undercooked or raw food and experiencing the symptoms of Gnathostomiasis, see your doctor for proper evaluation and testing.


Treatment of gnathostomiasis involves the removal of the larvae in surgery. However, this is only done if the larvae are in a reachable location. Additionally, treatment with anti-worm medication albendazole or ivermectin may be recommended.

To prevent gnathostomiasis’ accidental infection, it is best to educate people in the endemic areas not to consume undercooked or raw meat. However, many raw foods are cultural specialities in endemic areas, so it would be challenging to implement a wide scale preventative measure. A more culturally feasible way is to observe the FDA’s proper food handling and preservation, such as freezing the meat for several days (7 days at least) at -20 degrees Celsius.

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