Angiostrongylus cantonensis (Metastrongylidae)

Angiostrongylus cantonensis is a parasite that causes the potentially serious rat lungworm disease (human eosinophilic meningitis). It can be contracted by eating produce contaminated with snails or slugs infected with the parasite.  Angiostrongylus cantonensis is currently (Oct. 2012) to occur on Oahu and the Big Island in Hawaii.  Angiostrongylus cantonensis can cause harm to humans, and produce growers need to take precautions to limit the chance of their produce being contaminated with this pathogen. 

Species description or overview

Taxonomy & nomenclature

Impacts

Vectors

Dispersal and pathways

Human health issues

Department of Health advises public to wash produce thoroughly to prevent exposure to rare form of meningitis 
The parasite Angiostrongylus cantonensis causes a rare form of meningitis called eosinophilic meningitis or angiostrongyliasis (rat lungworm disease). The Hawaii Department of Health's advisory to wash produce addresses cases of rat lungworm disease on the Big Island (HDOA, 1/21/2009).

Distribution of Parmarion cf. martensi (Pulmonata: Helicarionidae), a new semi-slug pest on Hawaii Island, and its potential as a vector for human angiostrongyliasis 
The semi-slug Parmarion cf. martensi Simroth, 1893, was first discovered on Oahu, Hawaii, in 1996 and then on the island of Hawaii in 2004. This species, which is probably native to Southeast Asia, is abundant in eastern Hawaii Island, reportedly displacing the Cuban slug, Veronicella cubensis (Pfeiffer, 1840), in some areas. A survey in July-August 2005 found P. cf. martensi primarily in the lower Puna area of Hawaii Island, with an isolated population in Kailua-Kona (western Hawaii Island). It is now established in commercial papaya plantations, and survey participants reported it as a pest of lettuce and papaya in home gardens. Survey respondents considered P. cf. martensi a pest also because of its tendency to climb on structures where it deposits its feces and because of its potential to transmit disease. Individuals of this species were found to carry large numbers of infective third-stage larvae of the nematode Angiostrongylus cantonensis (Chen, 1935), the causative agent of human angiostrongyliasis and the most common cause of human eosinophilic meningoencephalitis. Using a newly developed polymerase chain reaction test, 77.5% of P. cf. martensi collected at survey sites were found infected with A. cantonensis, compared with 24.3% of V. cubensis sampled from the same areas. The transmission potential of this species may be higher than that for other slugs and snails in Hawaii because of the high prevalence of infection, worm burdens, and its greater association with human habitations, increasing the possibility of human-mollusk interactions.

Eosinophilic meningitis in Thailand
Angiostrongylus cantonensis was the probably cause of 484 typical cases of eosinophilic meningitis studied in Thailand (American J. Tropical Medicine and Hygene, 1975).

Angiostrongylus cantonensis infection fact sheet from the CDC
Rat lungworm disease (Angiostrongyliasis) information is provided by the Center for Disease Control.

Snails, slugs, and semi-slugs: A parasitic disease in paradise
An image of Angiostrongylus cantonensis larva obtained from a Parmarion martensi semi-slug collected in Hawaii, and information about parasite evaluation methods are provided by the Center for Disease Control.

Pest management systems to control rodents in and around packing sheds 
Diagrams and details about how to design rodent management systems incorporating bait stations and traps in and around produce packing stations are provided by CTAHR (University of Hawaii).

Avoid contracting Angiostrongyliasis (rat lungworm infection): Wash fresh fruits and vegetables before eating! 
Angiostrongyliasis overview and prevention measures are provided by the University of Hawaii College of Tropical Agriculture and Human Resources.

Best on-farm food safety practices: Reducing risks associated with rat lungworm infection and human eosinophilic meningitis 
Recent cases of eosinophilic meningitis have drawn attention to a foodborne parasitic infection that occurs in Hawaii, the Pacific Islands, southern and eastern Asia, and elsewhere. In late 2008, the Hawaii Department of Health reported that four people on the island of Hawaii were diagnosed with eosinophilic meningitis, secondary to rat lungworm infection. They may have been infected after eating fresh produce grown in the region that was contaminated with snails or slugs infected with the parasite Angiostrongylus cantonensis. Hawaii also experienced a cluster of five infections by this pathogen from November 2004 to January 2005 (Hochberg et al. 2007). According to the Hawaii Department of Health, reports of severe infections are uncommon. However, anecdotal evidence from a group of workshop attendees in the Puna district on Hawaii in January 2009 put the incidence rate much higher. Although reporting appears to lag behind actual disease incidence rate, the threat to residents and visitors is low. Due to the possible severity of the symptoms, it is important to practice preventive measures in your home garden or commercial farm, as well as in your kitchen.

Angiostrongylus cantonensis life cycle
Angiostrongylus cantonensis biology and life-cycle diagram are presented by Center for Disease Control.

DOH: Wash produce thoroughly to prevent rat lung worm
Angiostrongylus, or rat lung worm, which has sickened at least six people on Hawaii Island, can be prevented by washing produce thoroughly (Hawaii 247, 1/26/2009).

Emerging angiostrongyliasis in mainland China 
Our review of angiostrongyliasis in China found that the disease is emerging as a result of changes in food consumption habits and long-distance transportation of food. Enhanced understanding of angiostrongyliasis epidemiology, increased public awareness about the risks associated with eating raw food, and enhanced food safety measures are needed.

Eosinophilic meningitis attributable to Angiostrongylus cantonensis infection in Hawaii: Clinical characteristics and potential exposures 
The most common infectious cause of eosinophilic meningitis is Angiostrongylus cantonensis, which is transmitted largely by consumption of snails/slugs. We previously identified cases of giostrongyliasis that occurred in Hawaii from 2001 to 2005; the highest incidence was on the island of Hawaii. We now report symptoms, laboratory parameters, and exposures. Eighteen patients were evaluated; 94% had headache, and 65% had sensory symptoms (paresthesia, hyperesthesia, and/or numbness). These symptoms lasted a median of 17 and 55 days, respectively. Three persons recalled finding a slug in their food/drink. Case-patients on the island of Hawaii were more likely than case-patients on other islands to consume raw homegrown produce in a typical week (89% versus 0%, P < 0.001) and to see snails/slugs on produce (56% versus 0%, P = 0.03). Residents and travelers should be aware of the potential risks of eating uncooked produce in Hawaii, especially if it is from the island of Hawaii and locally grown.

An outbreak of eoinophilic meningitis caused by Angiostrongylus cantonensis in travelers returning from the Caribbean 
Outbreaks of eosinophilic meningitis caused by the roundworm Angiostrongylus cantonensis are rarely reported, even in regions of endemic infection such as Southeast Asia and the Pacific Basin. We report an outbreak of A. cantonensis meningitis among travelers returning from the Caribbean. We conducted a retrospective cohort study among 23 young adults who had traveled to Jamaica. Consumption of one meal (P=0.001) and of a Caesar salad at that meal (P= 0.007) were strongly associated with eosinophilic meningitis. Among travelers at risk, the presence of headache, elevated intracranial pressure, and pleocytosis, with or without eosinophilia, particularly in association with paresthesias or hyperesthesias, should alert clinicians to the possibility of A. cantonensis infection. (excerpted from the article's abstract)

Watch out Hawaii: Veggies may harbor rare parasite
Rat lungworm disease victims in Hilo, Hawaii, may have contracted the parasite by consuming raw vegetables (Scientific American, 1/8/2008).

Distribution of eosinophilic meningitis cases attributable to Angiostrongylus cantonensis, Hawaii 
During November 2004-January 2005, 5 cases of eosinophilic meningitis (EM) attributable to Angiostrongylus cantonensis infection were reported in Hawaii. To determine if this temporal clustering refl ected an increased incidence, we ascertained EM and A. cantonensis cases by systematic review of statewide laboratory and medical records for January 2001-February 2005 and generalized the data to population estimates. We identified 83 EM cases; 24 (29%) were attributed to A. cantonensis infection, which was included in the discharge diagnoses for only 2 cases. Comparison of A. cantonensis infection incidence rates (per 100,000 person-years) for the baseline (January 2001-October 2004) and cluster (November 2004-February 2005) periods showed statistically significant increases for the state as a whole (0.3 vs. 2.1), the Big Island of Hawaii (1.1 vs. 7.4), and Maui County (0.4 vs. 4.3). These findings underscore the need to consider the diagnosis of A. cantonensis infection, especially in the state of Hawaii.

In the news

Disease is blamed on home-grown veggies
A second Big Island resident is in a coma with rat lungworm disease, a rare ailment that can cause significant pain and trauma, including paralysis and blindness.

Disease outbreak on Big Island raising alarm among residents 
The rat lungworm disease that put two Big Island residents into comas is bringing attention to an illness confirmed in only 33 cases in Hawai'i since 2001 (Honolulu Advertiser, 2/8/2009).

Hawaii parasite victim slowly recovering after weeks in coma
The victim of one of the most severe cases of rat lungworm disease ever seen in Hawaii is slowly recovering after months of being in a coma (Honolulu Advertiser, 5/9/2009).

Full-text articles

An outbreak of eosinophilic meningitis caused by Angiostrongylus cantonensis in travelers returning from the Caribbean
A rat lungworm disease outbreak among 12 travelers was associated with consumption of Caesar salad in Jamaica (New England J. Medicine, 2/28/2002).

Distribution of Parmarion cf. martensi (Pulmonata: Helicarionidae), a new semi-slug pest on Hawaii Island, and its potential as a vector for human angiostrongyliasis 
The semi-slug Parmarion cf. martensi Simroth, 1893, was first discovered on Oahu, Hawaii, in 1996 and then on the island of Hawaii in 2004. This species, which is probably native to Southeast Asia, is abundant in eastern Hawaii Island, reportedly displacing the Cuban slug, Veronicella cubensis (Pfeiffer, 1840), in some areas. A survey in July-August 2005 found P. cf. martensi primarily in the lower Puna area of Hawaii Island, with an isolated population in Kailua-Kona (western Hawaii Island). It is now established in commercial papaya plantations, and survey participants reported it as a pest of lettuce and papaya in home gardens. Survey respondents considered P. cf. martensi a pest also because of its tendency to climb on structures where it deposits its feces and because of its potential to transmit disease. Individuals of this species were found to carry large numbers of infective third-stage larvae of the nematode Angiostrongylus cantonensis (Chen, 1935), the causative agent of human angiostrongyliasis and the most common cause of human eosinophilic meningoencephalitis. Using a newly developed polymerase chain reaction test, 77.5% of P. cf. martensi collected at survey sites were found infected with A. cantonensis, compared with 24.3% of V. cubensis sampled from the same areas. The transmission potential of this species may be higher than that for other slugs and snails in Hawaii because of the high prevalence of infection, worm burdens, and its greater association with human habitations, increasing the possibility of human-mollusk interactions.

Invasive species in the Pacific: A technical review and draft regional strategy
South Pacific Regional Environmental Programme (SPREP). Sherley, Greg (ed.) . 2000. Invasive species in the Pacific: A technical review and draft regional strategy. Apia, Samoa: South Pacific Regional Environment Programme. ISBN: 982-04-0214-X.

Emerging angiostrongyliasis in mainland China 
Our review of angiostrongyliasis in China found that the disease is emerging as a result of changes in food consumption habits and long-distance transportation of food. Enhanced understanding of angiostrongyliasis epidemiology, increased public awareness about the risks associated with eating raw food, and enhanced food safety measures are needed.

Changing epidemiology of Angiostrongyliasis cantonensis in Okinawa prefecture, Japan 
Okinawa Prefecture experienced an outbreak of angiostrongyliasis in January of2000 (I). The origin ofthe infection's outbreak could not be identified. We examined the past records of Angiostrongylus eantonensis (Ae) infection outbreaks and investigated the current distribution of Ae's intermediate and paratenic hosts with infective third-stage larvae in Okinawa. In order to find the infective larvae of Ae in the giant African snail, Achatina fulica, the pallial organ (lung) of the snail was compressed between two glass plates and examined under a microscope (2) (Figs. lA, IB). In other host animals, the whole body was digested in artificial gastric juice (l% pepsin/l% Hel), and the digested material was allowed to sediment; the sediment thus formed was then examined microscopically. In particular, albino rats were given larvae from Platydemus manokwari and Parmarion martensi orally with the specimen, and identification was made based on the morphology of the adult Ae recovered at 59 days post-inoculation.

Natural infection of the rat lungworm Angiostrongylus cantonensis in a Thai edible land snail, Hemiplecta distincta 
Rat lungworm found in edible snails is a source of meningoencephalitic angiostrongylosis in Thailand (1988).

Distribution of eosinophilic meningitis cases attributable to Angiostrongylus cantonensis, Hawaii 
During November 2004-January 2005, 5 cases of eosinophilic meningitis (EM) attributable to Angiostrongylus cantonensis infection were reported in Hawaii. To determine if this temporal clustering refl ected an increased incidence, we ascertained EM and A. cantonensis cases by systematic review of statewide laboratory and medical records for January 2001-February 2005 and generalized the data to population estimates. We identified 83 EM cases; 24 (29%) were attributed to A. cantonensis infection, which was included in the discharge diagnoses for only 2 cases. Comparison of A. cantonensis infection incidence rates (per 100,000 person-years) for the baseline (January 2001-October 2004) and cluster (November 2004-February 2005) periods showed statistically significant increases for the state as a whole (0.3 vs. 2.1), the Big Island of Hawaii (1.1 vs. 7.4), and Maui County (0.4 vs. 4.3). These findings underscore the need to consider the diagnosis of A. cantonensis infection, especially in the state of Hawaii.

Abstracts

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