Angiostrongyliasis is caused by the parasitic nematode Angiostrongylus, primarily A. cantonensis. People can become infected by ingesting raw or undercooked snails/slugs that carry the parasite larvae. The larvae can then travel to the brain, causing meningitis. Symptoms include headache, neck stiffness, and fever. Diagnosis involves finding eosinophils in spinal fluid or blood. Treatment focuses on pain relief; prevention involves thoroughly cooking snails/slugs and washing produce.

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Angiostrongyliasis
Angiostrongyliasis (also known as Angiostrongylus Infection) is a parasitic infection caused by
Nematode Angiostrongylus . Angiostrongylus is a parasitic nematode that can cause severe
gastrointestinal or central nervous system disease in humans, depending on the
species. Angiostrongylus cantonensis, which is also known as the rat lungworm, its a parasitic
nematode (worm) that is transmitted between rats and mollusks (such as slugs or snails) in its
natural life cycle. Other animals that become infected such as freshwater shrimp, land crabs,
frogs, and planarians of the genus Platydemus, are transport hosts that are not required for
reproduction of the parasite but might be able to transmit infection to humans if eaten raw or
undercooked. Humans are accidental hosts who do not transmit infection to others. Most cases of
infection are diagnosed in Southeast Asia and the Pacific Basin, but the parasite has also been
found in Australia, some areas of Africa, the Caribbean, Hawaii and Louisiana. Outbreaks of
human angiostrongyliasis have involved a few to hundreds of persons; over 2,800 cases have
been reported in the literature from approximately 30 countries. It is likely that the parasite has
been spread by rats transported on ships and by the introduction of mollusks such as the giant
African land snail (Achatina fulica). In addition, the semi-slug, Parmarion martensi (native of
Southeast Asia) has spread in regions of Hawaii and is found to often be infected with A.
cantonensis, and the freshwater snail Pomacea canaliculata (native of South America) has been
introduced into Taiwan and China and has been implicated in outbreaks of disease in those
countries.
Risk Factors:
Risk factors for infection with A. cantonensis include the ingestion of raw or undercooked infected
snails or slugs; or pieces of snails and slugs accidentally chopped up in vegetables, vegetable juices, or
salads; or foods contaminated by the slime of infected snails or slugs. It is possible that ingestion of raw

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or undercooked transport hosts (freshwater shrimp, land crabs, frogs, etc. ) can result in human
infection, though this is less certain. In addition, contamination of the hands during the
preparation of uncooked infected snails or slugs could lead to ingestion of the parasite.
Causal Agents:
The nematode (roundworm) Angiostrongylus cantonensis, the rat lungworm, is the most
common cause of human eosinophilic meningitis. In addition, Angiostrongylus (Parastrongylus)
costaricensis is the causal agent of abdominal, or intestinal, angiostrongyliasis.
Signs and Symptoms:
 Abdominal Pain
 Fever
 Nausea
 Vomiting
 Neck stiffness
 Abnormal sensations of the arms and legs
 Intestinal inflammation.
Incubation Period:
The incubation period is not specifically known, but is thought to usually range from several
weeks to several months, possibly even up to 1 year. A. costaricensis is usually found in the
intestine (especially the ileocecal region) and can cause abdominal pain, fever, nausea and
vomiting. Abdominal findings can often mimic appendicitis, and infection is identified after
surgical removal of the appendix. In rare cases, the larvae enter the mesenteric arteries found in
the abdominal cavity where they mature into adults and can cause arteritis, infarction,
thrombosis, and gastrointestinal hemorrhage. Eggs produced by adult worms lodge in capillaries
and cause an inflammatory reaction as they degenerate. The immune system’s response to the
adults, larvae, and eggs can result in a massive eosinophilic inflammatory reaction, with
eosinophilic invasion of the intestinal wall and eosinophilic vasculitis. Intestinal obstruction and
perforation can occur, and deaths have been reported. Recurrent episodes of illness may occur
over several months. Most cases resolve spontaneously.

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Treatment
There is no specific treatment for A. cantonensis infection. There is some evidence that certain
supportive treatments may reduce the severity of headache and the duration of symptoms. Some
medication are give to reduced the severity of complication like , use of analgesics for pain and
corticosteroids , prednisolone 60 mg/day , prednisolone-mebendazole, anti-helminthic
(mebendazole 10 mg/kg/day or albendazole 15mg/kg/day two weeks, respectively).
Diagnosis:
A diagnosis of A. cantonensis is strongly suggested when symptoms suggest bacterial meningitis
but testing reveals eosinophilia either in the blood (>5%) or in cerebrospinal fluid (>10%) and
travel history reveals recent travel to endemic areas of the world. History of ingestion of raw or
undercooked intermediate hosts or possibly transport hosts is a crucial clue as well. However, ill
persons may not be aware of ingestion of foods that could lead to infection. Examination of the
CSF can reveal eosinophilia (>10% eosinophils), elevated protein, and low or normal CSF
glucose. It is important to note, however, that eosinophilia in the CSF and in the blood may not
be present on initial presentation or in late stages of infection. The CSF pressure is generally
elevated. Recovery of A. cantonensis from the CSF confirms the diagnosis; however, the
organism is rarely detected on microscopy as it can adhere to the meninges.
Serologic tests have been developed but are not commercially available. A few specialty or
research laboratories offer serologic tests, but the sensitivity and specificity of the tests may not
be optimal and the infection is often identified only on convalescent sera. In addition, some
research laboratories have developed PCR tests for use with CSF and tissue. Because of the
difficulty in making the diagnosis, it is important to rule-out other causes of eosinophilic
meningitis. Neuroimaging studies can be useful as there usually is an absence of focal lesions on
CT scan, which helps to distinguish A. cantonensis eosinophilic meningitis from focal lesions
which may be seen in neurocysticercosis and gnathostomiasis. Because eggs are not passed in
the feces, a stool examination is not useful for diagnosis.
Prevention & Control
Prevention of A. cantonensis infections involves educating persons residing in or traveling to
areas where the parasite is found about not ingesting raw or undercooked snails and slugs,

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freshwater shrimp, land crabs, frogs, and monitor lizards, or potentially contaminated vegetables,
or vegetable juice. Removing snails, slugs, and rats found near houses and gardens should also
help reduce risk. Thoroughly washing hands and utensils after preparing raw snails or slugs is
also recommended. Vegetables should be thoroughly washed if eaten raw.