The Giant African Land Snail (GALS), Lissachatina fulica, is a mollusk native to East Africa, particularly regions like Mozambique, Kenya, Tanzania, and Somalia. This terrestrial snail is one of the largest in the world, with shells that can reach up to 8 inches (20 cm) in length and 5 inches (13 cm) in diameter. Its conical shell typically displays a light brown coloration with distinctive dark brown vertical stripes. While appearing to be an ordinary garden dweller, this seemingly benign creature poses significant risks when introduced outside its native habitat.
Health Risks to Humans
Giant African Land Snails carry various pathogens and parasites, posing a direct health risk to humans. A primary concern is their role as an intermediate host for the rat lungworm, Angiostrongylus cantonensis. This parasite causes eosinophilic meningitis in humans, a serious condition affecting the brain and spinal cord.
Transmission often occurs through accidental ingestion of raw or undercooked snails or slugs, or unwashed produce contaminated with snail slime containing parasite larvae. Direct contact with the snail’s mucus also poses a risk. Symptoms of rat lungworm infection can vary from mild to severe, including headaches, stiff neck, tingling sensations in the skin, low-grade fever, nausea, and vomiting. The infection can lead to permanent neurological damage or be fatal.
Threats to Ecosystems and Agriculture
Giant African Land Snails inflict considerable damage on natural ecosystems and agricultural industries. These snails are voracious generalist feeders, consuming a wide variety of plants. Their diet includes valuable agricultural crops like vegetables, fruits, and ornamental plants, leading to significant crop loss and impacting food security.
They also feed on native vegetation, disrupting local ecosystems and outcompeting indigenous snail species for food. In addition to plant matter, GALS consume stucco, paint, and other building materials to obtain calcium for their shells, causing structural damage. Their presence and destructive activities are indicated by large mucus trails, ribbon-like feces, and damage to structures.
Why They Are a Potent Invasive Species
The Giant African Land Snail’s biological and behavioral traits contribute to its success as a highly invasive species. They have a rapid reproductive rate, allowing populations to expand quickly. GALS are hermaphroditic, meaning each individual snail has both male and female reproductive organs. After a single mating, a snail can store sperm and produce multiple clutches of eggs, laying up to 1,200 per year.
These snails exhibit considerable adaptability to various environments. While they thrive in tropical and subtropical climates, they can survive less ideal conditions, including colder temperatures, by entering a state of hibernation or aestivation (a period of inactivity during dry or hot conditions). In new environments, they typically lack natural predators that would control their populations. Their broad diet further enhances their invasive potential, enabling them to find sustenance in diverse habitats.
What to Do if You Encounter One
Encountering a Giant African Land Snail requires caution due to potential health risks. Avoid direct skin contact with the snail or its slime. If handling one, always wear gloves and wash your hands thoroughly with soap and water afterward. Thoroughly wash any fruits or vegetables grown in areas where these snails are present before consumption.
If you suspect you have found a Giant African Land Snail, report the sighting to your local agricultural or health authorities. These agencies provide specific instructions, as regulations and recommended actions vary by region. Reporting these invasive snails helps monitor their spread and implement control measures to protect human health and local ecosystems.