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For further information, see CMDT Part 35-27: Angiostrongyliasis
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Essentials of Diagnosis
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General Considerations
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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
In A cantonensis infection, disease is caused primarily by worm larvae migrating through the CNS and an inflammatory response to dying worms
A cantonensis can migrate from the brain to the pulmonary arteries
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Differential Diagnosis
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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
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No specific treatment is available
Antihelminthic therapy may be harmful for A cantonensis infection, since responses to dying worms may worsen with therapy
If antihelminthic treatment is to be used, albendazole is probably the best choice, and therapy should be early in the disease course (within 3 weeks of exposure)
Corticosteroids have commonly been used, and these are probably appropriate if antihelminthics are provided
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Most cases resolve spontaneously after 2–8 weeks
However, serious sequelae and death have been reported
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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
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