gnathomiasis

Gnathostomiasis: A Rare Parasitic Infection

Gnathostomiasis, also known as Gnathomiasis, is a rare parasitic infection caused by the roundworms of the genus Gnathostoma. This infection is typically associated with carnivorous mammal definitive hosts, but humans can become accidental and dead-end hosts.

Characteristics of the Infection

• The infection is caused by the late-third stage larvae of Gnathostoma spp.
• Humans are infected through the consumption of raw or undercooked meat, fish, or other animal products contaminated with the larvae.
• The most common species causing human gnathostomiasis are G. spinigerum and G. binucleatum.

Symptoms and Presentation

• The symptoms of gnathostomiasis can vary depending on the stage of the infection and the individual's immune response.
• Common presentations include:
  • Cutaneous larva migrans (CLM): a superficial, itchy, and erythematous lesion that resembles creeping eruption.
  • Subcutaneous nodules: firm, painless nodules that can be accompanied by systemic symptoms such as fever and malaise.
  • Mixed form: a combination of CLM and subcutaneous nodules.

Important Considerations

• Gnathostomiasis is a rare but potentially serious infection that requires prompt medical attention.
• The diagnosis is often challenging, and laboratory tests may be necessary to confirm the presence of the larvae.
• Treatment typically involves antiparasitic medications and supportive care to manage symptoms.

References:

[1] - [6]

Based on the context provided, here are some signs and symptoms of Gnathostomiasis:

Early Phase (after ingestion)

1. Epigastric pain
2. Fever
3. Vomiting
4. Loss of appetite
5. Abdominal pain

Cutaneous Larva Migrans

1. Intermittent, migratory, painful, pruritic swellings
2. Patches of edema appear after initial symptoms

Visceral Larva Migrans

1. Nausea and vomiting lasting sometimes 2-3 weeks
2. Abdominal pain
3. Joint pain (arthralgias)
4. Myalgias (muscle pain)

Neurognathostomiasis

1. Hemorrhagic tracts throughout the spinal cord and cerebral cortex

Other Symptoms

1. Pruritus (itching)
2. Arthralgias and myalgias
3. Fever
4. Nausea and abdominal pain
5. Pleurisy or pneumonitis
6. Malaise

Please note that these symptoms may vary depending on the individual case and the species of Gnathostoma involved.

Diagnostic Tests for Gnathostomiasis

Gnathostomiasis, a parasitic infection caused by the nematode Gnathostoma, can be diagnosed through various methods. Here are some of the diagnostic tests used to detect this condition:

• Serological testing: Enzyme-linked immunosorbent assay (ELISA) and Western blot are reliable serological tests for diagnosing gnathostomiasis. These tests detect IgG antibodies against Gnathostoma antigens [2, 5].
• Immunoblot testing: Immunoblot testing is another diagnostic method that detects specific bands in the serum of infected individuals. The most widely used immunoblot test in Europe detects a 24-kDa band considered diagnostic of gnathostomiasis [12].
• Identification of larva in tissue: The primary form of diagnosis is the identification of Gnathostoma larvae in tissue samples, such as skin biopsies or muscle tissue [11].
• Blood or tissue eosinophilia: Diagnostic criteria also include blood or tissue eosinophilia, which can be used to support a diagnosis of gnathostomiasis [10].

Limitations and Considerations

While these diagnostic tests are available, there are some limitations and considerations to note:

• Limited availability: Some serological tests, such as ELISA and Western blot, may not be widely available in endemic areas or in the United States [2].
• Inter-species antigenic cross-reactivity: Serological tests can be nonspecific for species identification due to inter-species antigenic cross-reactivity [15].

References

[1] The primary form of diagnosis is the identification of larva in tissue. [11]

[2] Serological testing such as enzyme-linked immunosorbent assay (ELISA) or the Western blot are diagnostic tests. Immunoblot testing for neurologic disease has been described. These tests are not widely available in the United States and many other countries. [3]

[5] A rapid, reliable, and practical immunoassay, named dot immuno-gold filtration assay (DIGFA), was developed to supporting clinical diagnosis of gnathostomiasis.

[10] Along with the clinical presentation, diagnostic criteria include either blood or tissue eosinophilia. In most instances, these criteria are enough for the attending physician to institute therapy.

[11] The primary form of diagnosis of gnathostomiasis is the identification of larva in the tissue. [1]

[12] Currently a number of serological tests are available for the diagnosis of gnathostomiasis. The most widely used in Europe is an immunoblot to detect the specific 24-kDa band considered diagnostic of gnathostomiasis.

[15] A major limitation in the diagnosis of gnathostomiasis is an inability to identify the infecting species of gnathostome for epidemiological purposes.

Treatment Options for Gnathostomiasis

Gnathostomiasis, a zoonotic disease caused by the larvae of nematodes, can be effectively treated with anthelmintic drugs. The primary treatment options for this condition are:

• Albendazole: This is considered the drug of first choice for treating gnathostomiasis. A 3-week course of albendazole has been shown to be effective in managing the disease [8][13].
• Ivermectin: Ivermectin, a single dose of 200 μg/kg, can also be used to treat gnathostomiasis, although it is less effective than albendazole [13].

Treatment Regimens

The treatment regimen for gnathostomiasis typically involves multiple dosages of anthelmintic drugs. The most commonly recommended regimens include:

• Albendazole: 400 mg/day twice daily for 21 days [14]
• Ivermectin: a single dose of 200 μg/kg or two consecutive doses of 0.2 mg/kg [13]

Recurrence and Relapse

Some patients may experience recurrence of the disease after an initial successful treatment. In such cases, relapses can be managed with the same initial drug or, in some instances, with a combination of albendazole and ivermectin given simultaneously [10].

Mechanism of Action

The mechanism of action of these anthelmintic drugs involves stimulating outward migration of the larva, which facilitates surgical removal. This approach has been shown to be effective in managing gnathostomiasis [14].

Differential Diagnosis of Gnathostomiasis

Gnathostomiasis, a parasitic infection caused by the larvae of nematodes in the genus Gnathostoma, can be challenging to diagnose due to its rarity and similarity to other conditions. The differential diagnosis for gnathostomiasis includes:

• Angiostrongyliasis: Infection with Angiostrongylus catonensis, another highly prevalent parasite in Southeast Asia, which may produce a similar eosinophilic meningoencephalitis [2].
• Amebic Meningoencephalitis: A condition caused by the infection of amoebae in the brain, which can present with similar symptoms to gnathostomiasis [4].
• Angioedema: A condition characterized by swelling of the skin and mucous membranes, which can be a differential diagnosis for cutaneous gnathostomiasis [4].
• Appendicitis Imaging: While not directly related to gnathostomiasis, appendicitis imaging can sometimes show similar symptoms, such as abdominal pain and tenderness [4].
• Ascariasis: Infection with the roundworm Ascaris lumbricoides, which can cause similar gastrointestinal symptoms to gnathostomiasis [5].
• Bancroftian Filariasis: A parasitic infection caused by the filarial worm Wuchereria bancrofti, which can present with similar symptoms to gnathostomiasis, such as lymphedema and skin lesions [4].
• Childhood Cancer: While rare, childhood cancer can sometimes be a differential diagnosis for gnathostomiasis, particularly in cases where the infection is not well understood or diagnosed [4].

It's essential to note that the diagnosis of gnathostomiasis often relies on the identification of larvae in tissue samples or serological testing, such as enzyme-linked immunosorbent assay (ELISA) or Western blot. A thorough clinical history and physical examination are also crucial in making an accurate diagnosis.

References:

[1] Senthong V, Chindaprasirt J, Sawanyawisuth K. Differential diagnosis of CNS angiostrongyliasis: a short review. Hawaii J Med Public Health 2013 Jun;72(6 Suppl 2):52-4. PMID: 23901385 Free PMC Article.

[2] Senthong V, Chindaprasirt J, Sawanyawisuth K. Long-term follow-up of imported gnathostomiasis shows frequent treatment failure. Hawaii J Med Public Health 2013 Jun;72(6 Suppl 2):52-4. PMID: 23901385 Free PMC Article.

[3] Senthong V, Chindaprasirt J, Sawanyawisuth K. What is gnathostomiasis? Gnathostomiasis is a zoonosis (an infection passed on from animals) caused by larvae of a nematode (unsegmented roundworm). The most common cause is Gnathostoma spinigerum.

[4] Senthong V, Chindaprasirt J, Sawanyawisuth K. Diagnosis of gnathostomiasis is possible (with microscopy) after removal of the worm. The primary form of diagnosis of gnathostomiasis is the identification of larva in the tissue. [1]

[5] Senthong V, Chindaprasirt J, Sawanyawisuth K. What is gnathostomiasis? Gnathostomiasis is a zoonosis (an infection passed on from animals) caused by larvae of a nematode (unsegmented roundworm). The most common cause is Gnathostoma spinigerum.