Taenia saginata (the beef tapeworm) is the most common cause of tapeworm disease. Immature forms of the tapeworm develop in the muscles of animals that have eaten tapeworm eggs while grazing on infected grass. People are infected when they eat raw or undercooked beef. The adult tapeworms develop in the person's small intestine and segments of the worms containing eggs are deposited in the environment when the person defecates. This is how the cycle is continued.
Hydatid disease, caused by dog tapeworm, is transmitted when a person ingests the eggs of Echinococcus granulosus in food contaminated with dog faeces. This disease may cause symptoms in women that resemble ‘false pregnancy', because its effect is to enlarge the liver and cause the abdomen to swell so the woman may appear to be pregnant. The infection may also lodge in the lung or the brain. The prevention of disease caused by dog tapeworm is through personal hygiene when handling food and thorough washing of raw foods, especially if they have come into contact with soil.
Fish tapeworm (Diphyllobothrium latum) infects people through the consumption of raw fish and is more common in the lake areas where the diet is highly dependent on fish. The symptoms of infection with the fish tapeworm are similar to those of other tapeworm infections, i.e. abdominal discomfort or pain, nausea, vomiting or diarrhoea, and loss of appetite and weight loss. People should be advised only to eat fish that has been properly cooked.