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For further information, see CMDT Part 35-27: Angiostrongyliasis

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, prawns, or centipedes 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

  • A cantonensis infection

    • Disease is caused primarily by worm larvae migrating through the CNS and an inflammatory response to dying worms

    • A cantonensis can also migrate from the brain to the pulmonary arteries


  • A cantonensis is seen primarily in southeast Asia and some Pacific islands but also reported in Americas, Hawaii and Australia

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 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

  • Diagnosis can be confirmed with PCR, but this may be negative early in disease


  • No specific treatment is available

  • Antihelminthic therapy

    • May be harmful, since responses to dying worms may worsen with therapy

    • However, some experts recommend prompt therapy for any suspected infection or even known accidental snail or slug ingestion in an endemic area, as therapy is likely most beneficial early in the disease course

    • Albendazole, given within 3 weeks of exposure, is probably the best choice

  • Corticosteroids are probably appropriate if antihelminthics are given



  • Parasite deaths may exacerbate CNS inflammatory lesions


  • Most cases resolve spontaneously after 2–8 weeks

  • However, serious sequelae and death have been reported


  • 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



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