Angiostrongylus cantonesis

History

First discovered in 1935 in the pulmonary arteries in the heart of domestic rats. This worm is found in rats and bandicoots it is thought to mature in mammals indigenous to Southeast Asia, the East Indies, Madagascar and Oceania, with an infection rate that is as high is 88%. Africa and the Caribbean are currently showing Abdominal angiostrongyliasis which had been reported from Costa Rica, and occurs now most commonly in young children.

Morphology

Angiostrongylus cantonensis is a slender shaped worm with a mouth no lips or buccal cavity males range from 15.9mm to 19.0mm long, females can grow up to 21mm to 25mm. It is classified as a nematode a roundworm. The bursa is small and lacks a dorsal lobe. Spicules are long, slender and about equal in its length and form. An inconspicuous gubernaculum is present. In females there is intertwining of the intestine and uterine tubules.The eggs are thin shelled and unembryonated when laid.

Lifecycle

Angiostrongylus Cantonensis lay eggs in the pulmonary arteries , which are then carried to the capillaries and then break up into air spaces this is when they hatch. The Juvenilles migrate up to the trachea which are swallowed and also can be expelled in the feces. The Intermediate host are molluscs , this includes slugs, aquatic and even terrestrial snails. The Paratenic Hosts are Terrestrial planarians, freshwater shrimp, land crabs and even coconut crabs. It is also important to note frogs are found naturally to have the infective juvenile. Refer to this online diagram http://parasitology.informatik.uni-wuerzburg.de/login/n/h/0078.htmland The Center For Disease Control http://www.dpd.cdc.gov/dpdx/HTML/angiostrongyliasis.htm

Experimental Finds

Cheng et al conducted research into Angiostrongylus C by infecting American Oysters and Clams, Wallace and Rosen then successfully infected the crabs in which all Juveniles were infective to rats. This therefore shows that rats are the definitive host for this parasite. More recently Lindo John et al, have found a huge outbreak of Eosonophilic Menengitis in Jamacia, which is now being found in about 8% of snails in the studied population . Refer to http://www.cdc.gov/NCIDOD/EID/vol8no3/01-0316.htm

Effects on Humans

Angiostrongylus cantonesis is the most common cause of eosinophilic meningitis worldwide.Rats serve as the definitive host of Angiostrongylus cantonesis, whereas humans become infected by ingesting third-stage larvae in raw intermediate hosts, such as snails, prawns, fish, frogs or monitor lizards Infection has also rarely been acquired by the consumption of vegetables contaminated with infective larvae. Outside Southeast Asia and the Pacific Basin, where the infection is endemic, Angiostrongylus eosinophilic meningitis is seldom encountered." Baheti et al Symptoms often include low grade fevers, severe headaches and vomiting. Treatment in the early stage includes Thiabendazole.

References

N N Baheti1, M Sreedharan1, T Krishnamoorthy2, M D Nair1, K Radhakrishnan1 Eosinophilic meningitis and an ocular worm in a patient from Kerala, south India Journal Of Neurology Neurosurgery, and Psychiatry 2008;79:271; doi:10.1136/jnnp.2007.122093 Copyright © 2008 by the BMJ Publishing Group Ltd

Cheng T.C. 1965. The American Oyster and clam as an experimental Intermediate Hosts of Angiostrongylus Cantonesis.J.Parasitol' 51.926

Wallace, G.D., and L.Rosen.1966. Studies on Eosionphillic menengitis. Experimental infection of shrimp crabs with Angiostrongylus Cantonensis. Am J Epidemiol . 84:120-141

Roberts, L.S, and Janovy J Jr Foundations of Parasitology Chapters 25 pp 427-428 McGraw Hill Copyright 2005