Gnathostomiasis

Gnathostomiasis is a tissue nematode infection. Gnathostomiasis is a common illness in some regions of Southeast Asia. Many people are infected after eating raw fish (som fak in Thailand and sashimi in Japan). The main preventative measure is to thoroughly cook fish.

CASES/YEAR
0 (US); 3,250,000 (Global)
CATEGORY
Tissue Nematodes
AGENT TYPE
Helminths
OTHER NAMES
Gnathostoma spinigerum; Larva migrans profundus;
ACUITY
Subacute/Chronic
INCUBATION
3-4 weeks; [CCDM]
INITIAL SYMPTOMS
Fever, nausea/vomiting, diarrhea, and abdominal pain within 1-2 days of ingestion; [ID, p. 2374-5] Migratory, subcutaneous swellings occur 3 to 4 weeks after ingestion. [PPID, p. 3476]
PRECAUTIONS
COMMENTS
EPIDEMIOLOGY:
Humans, the accidental hosts, are usually infected after eating undercooked, larvae-containing chicken, pork, or freshwater fish. Snakes and frogs may also contain larvae. Transmission has been reported from drinking water contaminated with Cyclops (small crustacean, the first intermediate host). Dogs, cats and wild mammals are the definitive hosts. Gnathostomiasis is a common illness in some regions of Southeast Asia. Many people are infected after eating raw fish (som fak in Thailand and sashimi in Japan). The main preventative measure is to thoroughly cook fish.

FINDINGS:
Humans develop cutaneous larva migrans and eosinophilia within 3-4 weeks of ingestion. Patients may complain of vomiting, abdominal pain, and fever shortly after ingestion. Eye infection and eosinophilic myeloencephalitis are potential complications. Blindness is a complication of eye and CNS invasion. Migration of the larvae through the spinal canal and CNS can cause cranial nerve palsies, radicular pain, and paralysis. Characteristically, these symptoms wax and wane depending upon the location of the migrating larvae. Marked eosinophilia is present early. Eosinophilia may or may not be present during chronic infection. Other symptoms reported are cough, hematuria, diarrhea, neck stiffness, headache, and coma. [CCDM, p. 332-3; CDC website; ID, p. 2374-5; Guerrant, p. 784-5, 943; PPID, p. 3476; Cecil, p. 2135]
DIAGNOSTIC
Worms in surgical specimen; CSF: eosinophilic pleocytosis; [ID, p. 2374-5] Serological testing is available in Thailand and Japan; [Cecil, p. 2135] Suggested by eating raw fish or poultry with eosinophilia; Confirmed by ELISA test; [CCDM]
SCOPE
Mainly in Thailand, India, Japan, China, Malaysia, Philippines, Sri Lanka, Bangladesh, Myanmar, Laos, and Vietnam; Also in Mexico, Ecuador, and single report in Zambia; US and European cases usually imported from SE Asia; [Guerrant, Ch. 112]
SIGNS & SYMPTOMS
  • >fatigue, weakness
  • >fever
  • G abdominal pain
  • G diarrhea
  • G nausea, vomiting
  • H eosinophilia
  • N headache
  • N paresthesia
  • N stiff neck
  • R cough
  • S skin or subcutaneous nodule
  • S urticaria
  • S skin lesion, linear or serpiginous
  • U hematuria
  • *blindness
  • *brain abscess or lesion
  • *cranial neuropathy
  • *encephalitis
  • *meningitis
  • *myelitis
  • *paralysis
  • *stupor, coma
  • *uveitis
ANTIMICROBIC

Yes

VACCINE

No

ENTRY
Ingestion
SOURCE
Animal Tissue, Eating Contaminated Food, Eating Contaminated or Infected Meat, Eating Infected or Toxin-Containing Fish, Waterborne (Ingesting, Inhaling, or Swimming)
RESERVOIR
Cats, Dogs, Fish and Shellfish, Swine, Wild Animals
RISK FACTORS
  • Eat undercooked meat or fish
  • Travel to endemic area
TREATMENT
"Surgical removal or treatment with albendazole or ivermectin is recommended." [CDC website]
DRUG LINK
CDC DPDx: Gnathostomiasis
REFERENCES FOR CASES/YEAR
1.
2. (Global) Most cases have been reported in Thailand, Japan, and occasionally Mexico; [Cohen] A common illness in some localities of Southeast Asia; [PPID, p. 3476] No increase associated with growing popularity of sushi bars; Infections usually occur after eating from local restaurants in endemic countries lacking food regulations. [PMID 19597010] Gnathostomiasis is endemic in central and southern Laos. "Overall, 125 (29.8%) of 420 sera from the randomly selected participants were sero-positive by immunoblot technique, with anti-Gnathostoma IgG antibody against the 24 kDa fraction." [20804856] The seropositive rate was 62.5% in 531 patients tested at a tropical disease clinic in Bangkok during 2000-2005. [21329304] Neurognathostomiasis is endemic to Southeast Asia, particularly Thailand. "We found 24 reports describing a total of 248 patients with neurognathostomiasis published in English-language literature. . . . Although gnathostomiasis has been increasingly detected outside of Asia, particularly in Mexico, no cases of neurognathostomiasis have been reported in other regions." [21762569] Guesstimate: The population of Thailand is about 65 million. Assume 5% of population infected every year = 3,250,000;