Diseases Passed on by Worms and Snails

Michael Powell and Dr. Oliver Fischer describe a number of conditions in their book, 101 Illnesses you Don't Want to Get. A surprising number of these are caused by parasites such as snails and worms. They are generally clustered in tropical and subtropical countries and are a greater problem in lower socioeconomic areas. Many of these cases can be prevented or treated effectively but a lack of finance and basic health care often hampers the process.

Sicknesses Carried by Snails

Bilharzia is a disease caused by parasitic worms which are carried by freshwater snails. The worms develop in the snails and then enter the water where they infect human swimmers by penetrating the skin. They lay eggs that can ultimately cause damage to tissues in the intestines, bladder and other organs. Early symptoms include a rash and later on a fever, sore muscles, swollen glands and diarrhoea. If not treated, the eggs may end up in the brain or spinal cord and result in seizures or paralysis.

Parasitic Worm Infections in Humans

Worms are responsible for a number of infections which affect people in the following ways:

• Whipworms cause an intestinal infection called trichuriasis. This is found around the world but particularly in warm humid areas. If a large number of eggs are ingested, the results will include bloody diarrhoea, long term anaemia and rectal prolapse. Anti-parasitic drugs are available and the condition can be cured
• Roundworms cause an infection in humans called toxocariasis. This is often passed on through contact with the faeces of infected dogs and cats. There are three forms with symptoms ranging from fever, cough and abdominal pain, to swollen organs, asthma and pneumonia. In some cases the larvae enter the back of the eyes and can damage vision and cause blindness. Treatment is available and preventative measures such as washing hands and de-worming pets are advisable.
• Hookworm infection, also called ancylostomiasis, is common in northern Africa, northern Asia, southern Europe and parts of South America. Eggs are deposited into the ground via faeces and burrow into skin when people walk barefoot. Once in the body, they attach to the intestinal wall and feed off the person's blood. Symptoms start with itchy skin, a fever and cough and progress to abdominal pain and anaemia. The infection is easy to cure but if left untreated, can be fatal in children.
• Tapeworm cause an infection called taeniasis. This is picked up by eating raw or undercooked pork, beef and fish. The condition occurs in all parts of the world and does not often cause symptoms. Serious complications can arise when larval cysts travel from the stomach to areas such as the brain, eye or spinal cord.

Treatments for Worm Infestations

There are a number of anti-parasitic drugs available for treating worm infestations. Some of these work against several types of worms. Once the worms have been killed, some of the damage they have done can also be treated. This may be in the form of surgery to remove cysts or iron and vitamin supplements to counteract deficiencies.

Worm infestations can be unpleasant and life-threatening but can be prevented by good hygiene. Never eat raw or undercooked meat and wash hands after playing with pets. If symptoms arise, seek medical treatment immediately as worms are normally much easier to treat at the beginning of an infestation.

Reference : , by Michael Powell with Dr Oliver Fischer, Cassell Illustrated, 2005, ISBN 1-84403-389-9

101 Illnesses You Don't want to Get