Monday, May 17, 2004, 11:10 EDT (11:10 AM EDT)
CDCHAN-00200-2004-05-17-ADV-N
Giant African Land Snails: Pests Not Pets
Recent media reports have noted that giant African land snails (Achatina spp), also referred to as GALS, have become pets in the United States. These snails are major agricultural pests and could pose a public health threat if infected with the parasite Angiostrongylus cantonensis, the rat lung worm.
These snails, which can be larger than a person's hand, reproduce rapidly and have ravenous appetites for agricultural crops. Importation is illegal. For more information, including what to do if you own any of these snails, go to the United States Department of Agriculture (USDA)'s Animal and Plant Infection Service website. A toll-free number will be posted early next week so that people who have these snails can arrange without penalty to have them removed from their premises. USDA does not recommend that people dispose of them.
Human health risk is low
The human health risk, specifically for infection with A. cantonensis associated with giant African land snails, in the continental United States, is probably low. This type of snail is one of many types that can be infected with this parasite. It is unknown if any of the giant African land snails in the continental United States are infected. The only way snails can become infected is by eating infected rat stool. The likelihood a snail is infected if at all is considerably lower if the snail was bred indoors and kept in a tank than if it was collected from the outdoors or ever been outdoors.
Even if the snail is infected, the infection can be spread to humans only under unusual circumstances. People get infected by eating raw or undercooked snails or slugs (or freshwater prawns, crabs, or frogs). Whether the slime shed by infected snails can contain parasite larvae and infect people is unknown (e.g., if the slime is shed on a person's hand and then gets into the person's mouth or nose, or if the slime gets on produce that is eaten). People who handle snails of uncertain origin should wear gloves and thoroughly wash their hands.
Clinical summary
In infected people, symptoms, if any, typically develop
several days to weeks after the exposure. They may last for weeks to months,
while the body's immune system reacts to dying parasites (people are "dead-end
hosts" for the parasite). The following are key points: 1) A. cantonensis
is the most common infectious cause of eosinophilic meningitis; 2) paresthesias
and hyperesthesias are more often associated with this than with other types of
meningitis; 3) eosinophilia is not always present the first time peripheral
blood and cerebrospinal fluid (CSF) are examined; 4) the diagnosis usually is
not confirmed parasitologically (i.e., the parasite usually is not found in
CSF) but may be supported by serologic data (i.e., an antibody response to the
parasite); 5) treatment, if needed, usually is directed at symptoms (e.g., pain
medication, therapeutic lumbar punctures, and glucocorticoid therapy to
decrease headaches) rather than at the parasite (antiparasitic drugs could
increase the inflammatory reaction to dying parasites, but they may be
beneficial for some patients); and 6) patients typically fully recover.
Technical information about A. cantonensis,
including a schematic showing the life cycle of the parasite: http://www.dpd.cdc.gov/dpdx/HTML/angiostrongyliasis.htm
Public information on A. cantonensis: http://www.cdc.gov/ncidod/dpd/parasites/angiostrongylus/factsht_angiostrongylus.htm
USDA Web site on Giant African Land Snails: http://www.aphis.usda.gov/lpa/issues/gals/gals.html
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HAN Message Types
- Health Alert: Conveys the highest level of importance; warrants immediate action or attention. Example: HAN00001
- Health Advisory: Provides important information for a specific incident or situation; may not require immediate action. Example: HAN00316
- Health Update: Provides updated information regarding an incident or situation; unlikely to require immediate action. Example: HAN00309
- Info Service: Provides general information that is not necessarily considered to be of an emergent nature. Example: HAN00319
## This Message was distributed to State and Local Health Officers, Public Information Officers, Epidemiologists and HAN Coordinators as well as Clinician organizations ##
You have received this message based upon the information contained within our emergency notification database. If you have a different or additional e-mail or fax address that you would like us to use, please contact your State-based Health Alert Network program at your State or local health department.
- Content source: CDC Emergency Risk Communication Branch (ERCB), Division of Emergency Operations (DEO), Office of Public Health Preparedness and Response (OPHPR)
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