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Last updated Aug. 31, 2021

Written by: Ariana Adelman

Approved by: Krish Tangella MD, MBA, FCAP

National Museum of Health and Medicine

Image showing the Life cycle of Angiostrongyliasis.

What are the other Names for this Condition? (Also known as/Synonyms)

  • Angiostrongylus Cantonensis Infection
  • Angiostrongylus Costaricensis Infection
  • Angiostrongylus Infection

What is Angiostrongyliasis? (Definition/Background Information)

  • Angiostrongylus is a genus of microscopic, parasitic worms (also called nematodes) that can cause diseases of the gastrointestinal system or central nervous system in humans. Such diseases are referred to as Angiostrongyliasis
  • One species of this parasite, called Angiostrongylus cantonensis (or rat lungworm), is commonly found in Southeast Asia and the Pacific islands. This species of parasites can cause eosinophilic meningitis (meningitis with a high percentage of the white blood cell, eosinophils), in the fluid surrounding the brain or cerebrospinal fluid
  • Another species, called Angiostrongylus costaricensis, is commonly found in Latin America and the Caribbean.  This species can cause eosinophilic gastroenteritis, which is characterized by a large number of eosinophils in the gastrointestinal tract and blood
  • Angiostrongyliasis occurs either through the ingestion of infected snails and slugs that are raw or undercooked, or via consuming raw vegetables that are contaminated with slime or pieces of snails and slugs. The infection does not spread from one individual to another
  • Not all infected individuals may show symptoms of Angiostrongyliasis. When symptoms do occur, they can resemble bacterial meningitis or acute appendicitis, depending on the species that infected the individual. However, in most cases, the infections from these parasites resolve spontaneously without treatment

Who gets Angiostrongyliasis? (Age and Sex Distribution)

  • Individuals of all ages, races, ethnic groups, and both genders are susceptible to infection from Angiostrongylus cantonensis and Angiostrongylus costaricensis
  • The following groups are reported to show a higher prevalence of infection from Angiostrongylus costaricensis:
  • The following groups are reported to show a higher prevalence of infection from Angiostrongylus costaricensis:
    • Males
    • Young children between 6 and 12 years of age
    • People of higher socioeconomic status
  • Most infections of Angiostrongylus costaricensis occur in Latin America and the Caribbean. Additionally, there have been some reports in the U.S. and in the Republic of Congo
  • Most infections from Angiostrongylus cantonensis can be found in Southeast Asia, the Pacific Basin, and to a lesser extent in Australia, Caribbean region, Hawaii, and Louisiana

What are the Risk Factors of Angiostrongyliasis? (Predisposing Factors)

The risk factors for Angiostrongylus Cantonensis Infection include ingestion of the following:

  • Raw or undercooked snails or slugs that are infected
  • Produce covered in pieces of infected snails and slugs
  • Food contaminated by infected snail or slug slime
  • Shrimp, land crabs, frogs, and other organisms that feed on mollusks; though, this is very infrequent

The risk factors for Angiostrongylus Costaricensis Infection include ingestion of the following:

  • Infected slugs
  • Raw vegetables contaminated with slugs or their slime

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Angiostrongyliasis? (Etiology)

Angiostrongyliasis is caused by varied species of nematodes (worms) belonging to the genus Angiostrongylus. The following are specific modes of infection:

  • Angiostrongylus cantonensis is transmitted via rats and mollusks (slugs or snails). Consumption of slugs or snails that are infected with this parasite can cause infection in humans
    • Additionally, transport hosts such as shrimp, land crabs, frogs, and other species that feed on mollusks, can become infected and transmit the parasite to humans incidentally, if ingested while raw or undercooked
    • Angiostrongylus cantonensis worms eventually travel to the human brain and die
  • Angiostrongylus costaricensis is a worm that resides in rodents and uses mollusks as intermediate hosts. Larvae are transmitted through rat feces, which are then ingested by slugs
    • The larvae can enter the human body incidentally through the consumption of mollusks or food containing their slime
    • Angiostrongylus costaricensis eventually die in the human abdomen, because the parasite cannot complete its lifecycle in humans

What are the Signs and Symptoms of Angiostrongyliasis?

The signs and symptoms of Angiostrongyliasis may vary between the affected individuals. Some individuals, who are infected with Angiostrongylus cantonensis may not present any symptom(s). However, when symptoms develop, they may resemble those of bacterial meningitis, including:

  • Nausea and vomiting
  • Stiffness in the neck
  • Severe headaches and seizures
  • Abnormal sensations in the limbs

Some rare symptoms associated with Angiostrongylus cantonensis may include:

  • Migration of the parasite into the eye, causing problems with vision
  • Neurological dysfunction

Angiostrongylus costaricensis resides in the abdomen, specifically in the intestine, causing the following symptoms that resemble acute appendicitis:

  • Pain in the lower right quadrant (of stomach)
  • Fever
  • Nausea and vomiting

Additionally, an inflammatory reaction can be stimulated in response to the adult Angiostrongylus costaricensis parasite, larvae, and eggs that are released into the intestinal tissues.

Rarely, the larvae can migrate into the mesenteric arteries in the abdominal cavity and mature into adults. This can lead to the following conditions:

  • Inflammation of the arteries, reducing blood flow to organs
  • Death of tissue due to insufficient blood supply
  • Blood clots
  • Bleeding in the gastrointestinal tract

How is Angiostrongyliasis Diagnosed?

Angiostrongyliasis is difficult to diagnose, as bacterial meningitis, acute appendicitis, and other parasitic infections present with similar symptoms. The diagnosis of the infection is made by:

  • A thorough physical examination and an assessment of symptoms
  • An evaluation of the affected individual’s medical history and region of residence and travel history (to locations where the parasite is known to be present in foods that are consumed raw, such as mollusks)
  • Collection and analysis of cerebrospinal fluid (fluid that surrounds the brain) for individuals presenting with symptoms of Angiostrongylus Cantonensis Infection
    • In bacterial meningitis, the fluid may contain elevated levels of polymorphonuclear leukocytes, which help fight bacterial infections
    • In Angiostrongylus Cantonensis Infection, elevated levels of eosinophils (special types of white blood cells) are present in the fluid. However, these cells may be absent, if the test is performed in the very early or very late stages of the disease
    • Polymerase chain reaction (PCR) can also confirm the presence of Angiostrongylus cantonensis DNA present in the infected individual’s cerebrospinal fluid
    • Rarely, larvae can be found in the cerebrospinal fluid of individuals infected with Angiostrongylus cantonensis
  • A positive blood test for high levels of eosinophils may be indicative of Angiostrongylus costaricensis parasite being present. However, this factor is common to many parasitic infections
  • Taking biopsies of tissue specimens to detect Angiostrongylus costaricensis eggs and larvae

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Angiostrongyliasis?

Complications of Angiostrongyliasis may include the following:

  • Angiostrongylus Cantonensis Infection
    • Neurologic dysfunction
    • Death may occur in some cases of infection
  • Angiostrongylus Costaricensis Infection: Complications from surgery to remove segments of inflamed intestine

How is Angiostrongyliasis Treated?

Most cases of Angiostrongyliasis infection resolve spontaneously without treatment, since these parasites cannot permanently survive in the human body. When necessary, supportive treatment for symptoms may include:

  • Corticosteroids to reduce the inflammatory reaction
  • Repeated drainage of the cerebrospinal fluid to reduce headaches
  • Surgical intervention for Angiostrongylus Costaricensis Infection, to remove segments of inflamed intestine

How can Angiostrongyliasis be Prevented?

Angiostrongyliasis infections can be prevented by the following measures:

  • Refraining from eating raw slugs and snails (particularly in the endemic regions)
  • Educating people living in or traveling to areas with a high prevalence of these parasites found in raw mollusks, shrimp, land crab, frogs, and contaminated vegetables
  • Removing mollusks and rats from near one’s houses and gardens
  • Washing hands and utensils with warm water and soap following contact with (touching) raw mollusks
  • Washing vegetables thoroughly before consuming them raw

What is the Prognosis of Angiostrongyliasis? (Outcomes/Resolutions)

  • The prognosis of Angiostrongyliasis is typically good, as most affected individuals recover fully without treatment after about 6 weeks
  • Supportive treatments can successfully alleviate symptoms associated with this infection

Additional and Relevant Useful Information for Angiostrongyliasis:

  • The incubation period for Angiostrongylus Cantonensis Infection is approximately 1-4 weeks, and it typically lasts between 2-8 weeks. However, in some cases, the infection may last longer
  • The incubation period for Angiostrongylus Costaricensis Infection is unknown, and is believed to range anywhere from a few weeks to 1 year

What are some Useful Resources for Additional Information?

References and Information Sources used for the Article:

Helpful Peer-Reviewed Medical Articles:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 30, 2017
Last updated: Aug. 31, 2021