DurgicalDurgical
EN
Open the app

Microbiology · Other parasites of interest

Angiostrongylus (A. costaricensis, A. cantonensis) !

  • Parasite
  • For completeness

Rat worms that reach humans through slugs and snails. One inflames the gut of children in the Americas; the other causes meningitis.

Updated 2026-11-01

Also called: rat lungworm (A. cantonensis), angiostrongyliasis

At a glance

Family
Angiostrongylidae
Type
Metastrongylid nematodes
Size
Adults from a few millimetres to about two centimetres

Morphology

  • A. costaricensis: adults in the mesenteric arteries of the ileocaecal region; eggs and larvae in the bowel wall.
  • A. cantonensis: adults in the rat's pulmonary arteries; in humans they stay as young larvae in the nervous system.

Transmission

  • Eating raw or undercooked snails or slugs, or raw vegetables contaminated with them or their slime.
  • A. cantonensis also via raw paratenic hosts (crabs, freshwater shrimp).
  • Not spread from person to person.

Reservoir: Wild rodents (the cotton rat Sigmodon hispidus for A. costaricensis; Rattus rats for A. cantonensis)

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Life cycle

  1. Adults live in the rat's arteries (mesenteric or pulmonary, depending on species).
  2. First-stage larvae leave in the rat's faeces.
  3. Slugs and snails swallow them and they mature into infective larvae.
  4. The rat is infected by eating the mollusc, closing the cycle.
  5. Humans, accidental hosts, are infected by eating the mollusc or contaminated vegetables.
  6. A. costaricensis stays in the bowel wall; A. cantonensis migrates to the brain and does not complete its cycle.

Virulence factors

  • A. costaricensis: eggs and larvae cause eosinophilic granulomas, vasculitis and thrombosis in the terminal ileum, caecum and appendix.
  • Ischaemia can lead to necrosis, perforation or obstruction.
  • A. cantonensis: larvae dying in the nervous system trigger an intense eosinophilic reaction.

Diseases it causes

  • Angiostrongyliasis cantonensis: eosinophilic meningitis
  • Abdominal angiostrongyliasis (A. costaricensis): an ileocaecal mass that mimics appendicitis

Clinical picture

  • Abdominal: right lower quadrant pain, fever, vomiting and a palpable mass in children, with leucocytosis and eosinophilia; often operated on as appendicitis.
  • Meningeal: severe headache, neck stiffness, nausea, paraesthesiae; most patients recover.

Diagnosis

  • Abdominal: histopathology of the surgical specimen (worms in mesenteric vessels, eosinophilic granulomas); no validated serology.
  • Meningeal: cerebrospinal fluid with eosinophils; larvae are rarely seen. CSF PCR is available at reference centres.
  • Blood eosinophilia in both.

Treatment

Abdominal: surgery for complications; anthelmintics such as diethylcarbamazine or levamisole are discouraged because they may worsen inflammation or migration. Meningeal: supportive care with analgesia and corticosteroids; the role of albendazole is still debated.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

Prevention

  • Washing vegetables well and not eating raw snails, slugs or freshwater shrimp.
  • Handwashing after handling snails, including the giant African snail.
  • Rodent and mollusc control in gardens.

Test yourself

Think of the answer, then tap the question to see it.

Which parasite is the most frequent cause of eosinophilic meningitis worldwide?

Angiostrongylus cantonensis, the rat lungworm.

How does A. costaricensis angiostrongyliasis present?

As an abdominal picture in children that mimics appendicitis, with an ileocaecal mass and eosinophilia from granulomas and vasculitis in the bowel wall.

What are the intermediate hosts of Angiostrongylus?

Slugs and snails; rats are the definitive hosts and humans are accidental.

Add to my cards (3)

← Back to the group: Other parasites of interest

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: CDC - DPDx - Angiostrongyliasis (CDC, 2024); Abdominal angiostrongyliasis, report of two cases and analysis of published reports from Colombia (Biomédica (Instituto Nacional de Salud), 2020).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.