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Key Features

Essentials of Diagnosis

  • Eosinophilic meningoencephalitis

  • Transient cranial neuropathies

General Considerations

  • Nematodes of rats of the genus Angiostrongylus cause two distinct syndromes in humans

    • Angiostrongylus cantonensis, the rat lungworm, causes eosinophilic meningoencephalitis

    • Angiostrongylus costaricensis causes gastrointestinal inflammation

  • In both diseases, human infection follows ingestion of larvae within slugs or snails (and also crabs or prawns for A cantonensis) or on material contaminated by these organisms

  • Since the parasites are not in their natural hosts, they cannot complete their life cycles, but they can cause disease after migrating to the brain or gastrointestinal tract

  • In A cantonensis infection, disease is caused primarily by worm larvae migrating through the CNS and an inflammatory response to dying worms

Demographics

  • A cantonensis is seen primarily in southeast Asia and some Pacific islands

Clinical Findings

Symptoms and Signs

  • After an incubation period of 1 day to 2 weeks, presenting symptoms and signs include

    • Headache

    • Stiff neck

    • Nausea, vomiting

    • Cranial nerve abnormalities

    • Paresthesias

Differential Diagnosis

  • Tuberculous, coccidioidal, or aseptic meningitis

  • Neurocysticercosis

  • Neurosyphilis

  • Lymphoma

  • Paragonimiasis

  • Echinococcosis

  • Gnathostomiasis

Diagnosis

  • Diagnosis strongly suggested by finding eosinophilic CSF pleocytosis (over 10% eosinophils) in patients with a history of travel to endemic area

  • Peripheral eosinophilia may not be present

  • Definitive diagnosis is made by recovery of A cantonensis larvae from the CSF and the eyes, although this is uncommon

Treatment

  • No specific treatment is available

  • Antihelminthic therapy is probably not indicated, since responses to dying worms may worsen with therapy

  • Corticosteroids have been used in severe cases

Outcome

Complications

  • Parasite deaths may exacerbate CNS inflammatory lesions

Prognosis

  • Most cases resolve spontaneously after 2–8 weeks

  • However, serious sequelae and death have been reported

Prevention

  • Controlling rat population

  • Cooking snails, prawns, fish, and crabs for 3–5 min or by freezing them (–15°C for 24 h)

  • Examining vegetables for mollusks before eating

  • Washing contaminated vegetables to eliminate larvae contained in mollusk mucus is not always successful

When to Admit

  • All patients

References

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Barratt  J,  et al. Angiostrongylus cantonensis: a review of its distribution, molecular biology and clinical significance as a human pathogen. Parasitology. 2016 Aug;143(9):1087–118.
[PubMed: 27225800]  
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Martins  YC,  et al. Central nervous system manifestations of Angiostrongylus cantonensis infection. Acta Trop. 2015 Jan; 141(Pt A):46–53.
[PubMed: 25312338]  
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Ramirez-Avila  L,  et al. Eosinophilic meningitis due to Angiostrongylus and Gnathostoma species. Clin Infect Dis. 2009 Feb 1; 48(3):322–7.
[PubMed: 19123863]  

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