NAME: Angiostrongylus cantonensis
SYNONYM OR CROSS REFERENCE: Parastrongylus cantonensis, rat lungworm, angiostrongyliasis, cerebral angiostrongyliasis, eosinophilic meningitis, eosinophilic meningoencephalitis.
CHARACTERISTICS: A. cantonensis is a parasitic nematode from the genus Angiostrongylus (1-4). Females are 21 mm to 25 mm long, while the males are 16 mm to 19 mm long. Mature worms live in the pulmonary arteries of rats and produce fertilized eggs that develop into first-stage larvae. These larvae migrate up the trachea, are swallowed and expelled with the feces. They remain viable and infectious in the feces or freshwater for several weeks. The life cycle is completed only if these larvae are ingested by a mollusc intermediate host (land snails or slugs). In about 2 weeks, the larvae then mature into infectious third-stage larvae that maintain infection for the life of the molluscs. Shrimp, fish, crabs, frogs, predacious land planarians, or monitor lizards may eat the infected mollusks and serve as paratenic hosts. Rodents ingest either the mollusks or paratenic hosts and become infected. Humans (dead end hosts) can become infected by ingesting raw contaminated intermediate or paratenic hosts or vegetables contaminated with third stage larvae.
PATHOGENICITY/TOXICITY: Infection may be mild and death is rare (4). Once infective larvae of A. cantonensis are ingested, they invade the intestinal tissue and can cause enteritis. The larvae then pass through the liver and lungs before reaching the nervous system. While the nematode moves through the lung, cough, rhinorrhoea, sore throat, malaise and fever can develop. After around 2 weeks, when the nematode reaches the central nervous system (CNS), the main clinical manifestation is eosinophilic meningitis, characterized by headache, neck stiffness, parasthesia, vomiting, fever, nausea and blurred vision or diplopia. Children may also feel sleepy, and experience abdominal pain, or weakness of the extremities. Eosinophilic pleocytosis, eosinophilic encephalitis and ocular angiostrongyliasis may also occur (3, 4).
EPIDEMIOLOGY: Angiostrongyliasis is endemic in Southeast Asia, Australia, the South Pacific and the Caribbean (2, 4). Sporadic cases can occur throughout the world and may be linked to travel in endemic areas (4, 5).
INFECTIOUS DOSE: Unknown.
MODE OF TRANSMISSION: Transmission is based on food-borne routes, ingestion of raw or insufficiently cooked contaminated molluscs, crustacean, or other hosts; or ingestion of vegetables contaminated with infectious larvae (4).
ZOONOSIS: Yes, illness can be transmitted to humans through ingestion of infectious larvae carried by reservoir hosts (6).
VECTORS: Molluscs, crustaceans, flatworms, frogs and monitor lizards (4).
DRUG SUSCEPTIBILITY: There is no specific treatment for angiostrongyliasis. A cantonensis is susceptible to albendazole and mebendazole, but a systemic response to dying worms may make the condition worse (2, 3, 7).
PHYSICAL INACTIVATION: Inactivation can be achieved by exposure to -15°C for 12 to 24 hours or by boiling for 2 - 3 minutes (11).
SURVIVAL OUTSIDE HOST: Third stage larva outside a host can survive for up to a week in water (12).
SURVEILLANCE: Monitor for clinical symptoms. Diagnosis is based on a history of exposure and presence of eosinophils in cerebrospinal fluid (CSF) (4). Serological tests can also be used to detect antibodies in serum or cerebral spinal fluid (CSF) (2-4).
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: Symptoms are usually mild and the infection is generally self-limiting (4). Supportive treatment to reduce pain and inflammation, such as corticosteroids, has been used (3, 4). Lumbar puncture can be used to relieve intracranial pressure. Patients with ocular angiostrongyliasis require surgery to remove worms from the eye. Anthelmintic drugs, such as albendazole and mebendazole, may be administered, but can also exacerbate the neurological symptoms due to an inflammatory response to dying worms.
LABORATORY-ACQUIRED INFECTIONS: None reported.
SOURCES/SPECIMENS: Infected tissues or cerebrospinal fluid, molluscs and other intermediate or paratenic hosts (2).
PRIMARY HAZARDS: Accidental perenteral inoculation, or ingestion of infected organisms.
SPECIAL HAZARDS: None.
RISK GROUP CLASSIFICATION: Risk Group 2.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eyes protection must be used where there is known or potential risk of exposure to splashes (13).
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities (13).
SPILLS: Allow aerosols to settle and, while wearing protective clothing, gently cover the spill with paper towels and apply suitable disinfectant, starting at the perimeter, working inwards towards the centre. Allow sufficient contact time before clean up , and then repeat (13, 14).
DISPOSAL: Decontaminate before disposal by steam sterilization, incineration, or chemical disinfection (13).
STORAGE: In locked, leak-proof containers that are appropriately labelled and secured (13).
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: October 2010
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.
Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2010