Angiostrongylus cantonensis, rat lungworm, a nematode parasite.
Various species of rats are the definitive hosts of the parasite, known as the rat lungworm. Rats can infect only snails and slugs, which are the intermediate hosts. Transmission to humans occurs by consuming infected snails or slugs or contaminated raw produce or vegetable juices. Infective larvae have also been found in freshwater shrimp, crabs, and frogs.
Most described cases have occurred in Asia and the Pacific Basin (such as in parts of Thailand, Taiwan, mainland China, the Hawaiian Islands, and other Pacific Islands); however, cases have been reported in many areas of the world, including the Caribbean.
Incubation period is typically 1–3 weeks but ranges from 1 day to >6 weeks. A. cantonensis is considered the most common infectious cause of eosinophilic meningitis in humans. Common manifestations include headache, photophobia, stiff neck, nausea, vomiting, fatigue, and body aches. Abnormal skin sensations (such as tingling or painful feelings) are more common than in other types of meningitis. A low-grade fever might be noted. Symptoms are usually self-limited but may persist for weeks or months. Severe cases can be associated with paralysis, blindness, or death.
Typically presumptive, on the basis of clinical and epidemiologic criteria in people with otherwise unexplained eosinophilic meningitis. PCR testing of cerebrospinal fluid is available from CDC (www.cdc.gov/dpdx; 404-718-4745; email@example.com). Serum antibody testing may be available in reference laboratories.
The larvae die spontaneously and supportive care usually suffices, including analgesics for pain and corticosteroids to limit inflammation. No antihelminthic drugs have been proven to be effective in treatment.
Food and water precautions, particularly:
Avoid eating raw or undercooked snails, slugs, and other possible hosts.
Eat raw produce, such as lettuce, only if it has been thoroughly washed or treated with bleach. Such measures might provide some protection but may not eliminate the risk.
Wear gloves (and wash hands) if snails or slugs are handled.
Chotmongkol V, Sawadpanitch K, Sawanyawisuth K, Louhawilai S, Limpawattana P. Treatment of eosinophilic meningitis with a combination of prednisolone and mebendazole. Am J Trop Med Hyg. 2006 Jun;74(6):1122–4.
Hochberg NS, Blackburn BG, Park SY, Sejvar JJ, Effler PV, Herwaldt BL. Eosinophilic meningitis attributable to Angiostrongylus cantonensis infection in Hawaii: clinical characteristics and potential exposures. Am J Trop Med Hyg. 2011 Oct;85(4):685–90.
Wang QP, Lai DH, Zhu XQ, Chen XG, Lun ZR. Human angiostrongyliasis. Lancet Infect Dis. 2008 Oct;8(10):621–30.