Angiostrongyliasis Cantonensis

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 (GI) 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, such as salads, 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 GI tract

• A cantonensis infection

  • Caused primarily by worm larvae migrating through the central nervous system (CNS) and an inflammatory response to dying worms

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

Demographics

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

• In one study, A cantonensis was responsible for most cases of eosinophilic meningitis in Vietnam

CLINICAL FINDINGS

Symptoms and Signs

• After an incubation period of 1 day to 2 weeks

  • Headache

  • Stiff neck

  • Nausea, vomiting

  • Cranial nerve abnormalities

  • Paresthesias

DIAGNOSIS

• Diagnosis strongly suggested by finding eosinophilic cerebrospinal fluid pleocytosis (> 10% eosinophils) in patients with a history of travel to an endemic area

• Peripheral eosinophilia may not be present

• Diagnosis can be confirmed with polymerase chain reaction, but this may be negative early in disease

TREATMENT

• 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 likely the best choice

• Corticosteroids are probably appropriate if antihelminthics are given

• Ocular infection is treated surgically

OUTCOME

Complications

• Parasite deaths may exacerbate CNS inflammatory lesions

When to Admit

• All patients

REFERENCES