When discussing the world’s deadliest creatures, snails may not be the first animals that come to mind. However, these seemingly harmless gastropods are responsible for a significant number of human fatalities every year. Freshwater snails, in particular, are carriers of a parasitic disease called schistosomiasis, which infects almost 250 million people worldwide, primarily in Asia, Africa, and South America. This makes them one of the most dangerous parasites on the planet, according to a disease ecologist at Stanford University’s Hopkins Marine Station.
Different Ways Snails Kill People
There are multiple ways in which snails can pose a threat to humans. One of the primary ways is through the transmission of diseases caused by the parasites they host.
Schistosomiasis, also known as snail fever, is caused by flatworm parasites that live in the blood vessels of infected individuals. The disease spreads when people come into contact with contaminated water, where the snail hosts release the parasite larvae. Once these larvae penetrate the human skin, they develop into adult worms, leading to various health complications such as anemia, abdominal pain, and even organ damage. In severe cases, the disease can cause more than 200,000 deaths each year, as mentioned on Roaring Earth.
Another example of a parasitic snail-related disease is eosinophilic meningitis, caused by the worm Angiostrongylus cantonensis. This worm is found mainly in tropics and subtropics and is acquired by eating infected snails. The worm travels to the brain, causing inflammation of the lining of the brain and spinal cord.
Both schistosomiasis and eosinophilic meningitis can be severe and fatal if left untreated. Thus, snails indirectly contribute to the high number of deaths through the transmission of these dangerous parasites.
Another way snails can be deadly to humans is through their venom. Some species of marine cone snails, known as killer snails, possess a complex venom delivery system. These snails use a harpoon-like tooth to inject their prey with venom, which can be extremely toxic and fatal to humans. Cone snail venom contains powerful neurotoxins that can lead to paralysis or death in extreme cases.
Symptoms and Effects
When an individual comes into contact with the parasitic worms that certain snails carry, they may experience a variety of initial symptoms. These can include abdominal pain, diarrhea, and blood in the stool, with the classic sign of infection being blood in the urine. The parasites, which can penetrate the skin, migrate through the body until they end up in the blood vessels where they can live for many years, even decades.
The long-term effects of infection by these parasitic worms can be devastating. Known as schistosomiasis or bilharzia, this disease is second only to malaria in terms of its impact on humans. The long-term effects of schistosomiasis can include liver damage, kidney failure, infertility, and bladder cancer. Furthermore, the infection can also cause growth retardation in children and cognitive impairment.
Prevention and Treatment
Preventing infection from snails starts by being cautious around fresh water bodies. It’s vital to avoid skin contact with fresh water that might be contaminated with Schistosoma eggs and parasites. Some practical measures to reduce the risk of infection include:
- Wearing protective clothing when in or around potentially contaminated bodies of water
- Avoiding activities such as swimming, wading, or washing in fresh water where infected snails might be present
- Boiling or treating water with chlorine before use, if it is suspected to be contaminated
- Improving sanitation infrastructure to reduce contamination of water sources
If an individual becomes infected with the parasites spread by snails, medical intervention is necessary to treat the infection. The primary treatment for schistosomiasis is the drug praziquantel, which is effective against all major species of Schistosoma. A few points to remember during medical intervention include:
Praziquantel should be prescribed by a healthcare professional and taken as per the prescribed dosage and duration.
Monitor symptoms closely, and report any worsening or new symptoms to the healthcare provider.
In addition to praziquantel, supportive care might be necessary in some cases, depending on the severity of symptoms.
Preventing reinfection is crucial, so continue to practice protective measures whenever exposure to potentially infected snails or water sources is a possibility.