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Angiostrongylus cantonensis infection
Other Resources UpToDate PubMed

Angiostrongylus cantonensis infection

Contributors: David L. McCollum MD, J. Martin Rodriguez MD, James H. Willig MD, MSPH
Other Resources UpToDate PubMed


Angiostrongyliasis is a zoonotic disease resulting from infection with two species of a parasitic nematode (roundworm), Angiostrongylus cantonensis (also known as rat lungworm) and Angiostrongylus costaricensis. The predominant clinical manifestations in humans are eosinophilic meningitis for A. cantonensis and enteritis for A. costaricensis. This summary focuses on angiostrongyliasis resulting from infection with A. cantonensis.

Angiostrongylus cantonensis is endemic in South Asia, Australia, and islands of the Caribbean, Pacific (including Hawaii), and Indian Ocean. Eosinophilic meningitis due to A. cantonensis has been reported in US travelers to these regions. Angiostrongylus cantonensis lungworm has been reported in wildlife hosts in southeastern United States.

The life cycle is similar for both species. In the definite host (rats), adult worms lay eggs, and larvae hatch from them, migrate, and get excreted in the rat's feces. These larvae are then swallowed by snails and slugs. These slugs may then be eaten by a variety of creatures including frogs, crabs, fish, etc. The predominant manner in which humans become infected is ingestion of raw snails that are harboring the larva. Similarly, ingestion of other uncooked or undercooked freshwater species that have consumed infected snails or slugs such as frogs, shrimp, crabs, and fish can also lead to disease. Fruits and vegetables can also carry larvae and cause infection. Children may infect themselves by putting their hands in their mouth after playing with affected creatures.

After A. cantonensis ingestion, larvae migrate from the gastrointestinal tract and hematogenously arrive in the central nervous system (CNS). This is the most common cause of eosinophilic meningitis worldwide. Patients develop symptoms when inflammation increases in conjunction with the worms dying. Symptoms typically occur 7-35 days after ingestion of the larvae and include headache, nausea, vomiting, and paresthesias of the extremities. Many of the symptoms are due to increased intracranial pressure. Focal signs are uncommon except for cranial nerve palsies. Typically, patients recover without sequelae in several weeks. Angiostrongylus cantonensis occasionally presents with blurred vision due to the worm invading the vitreous chamber.


B83.2 – Angiostrongyliasis due to Parastrongylus cantonensis

35033008 – Infection by Angiostrongylus cantonensis

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Differential Diagnosis & Pitfalls

Other causes of Eosinophilic meningitis include: 
  • Gnathostomiasis – may have migratory cutaneous swellings. CNS disease may be hemorrhagic and lumbar puncture may reveal red cells.
  • Schistosomiasis – the neurological manifestations are most commonly related to spinal cord disease.
  • Cysticercosis – commonly presents with seizures. Brain magnetic resonance imaging (MRI) may show cysts with characteristic scolex.
  • Toxocariasis – look for contact with dogs.
  • Baylisascariasis – the raccoon roundworm, look for exposure history.
  • Paragonimiasis – CNS presentations are the most common extrapulmonary manifestation of the lung fluke.
  • Coccidioidomycosis – look for appropriate exposure to endemic region (ie, the Southwest US)
  • Leukemia and Lymphoma – subtypes may have eosinophilic predominance and cause meningitis.
  • Hypereosinophilic syndrome
  • Foreign bodies such as ventricular shunt

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Last Updated:10/01/2023
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Angiostrongylus cantonensis infection
A medical illustration showing key findings of Angiostrongylus cantonensis infection : Severe headache, Nausea/vomiting, Nuchal rigidity, Paresthesias, CSF eosinophilia, EOS increased
Copyright © 2024 VisualDx®. All rights reserved.