Tapeworm is a term that is used to describe a group of parasitic worms that live in the intestine of animals as well as humans. Tapeworms belong to a branch of platyhelminths known as the cestodes. They are highly specialized parasites.
Common species of tapeworms that infect the human intestine
Tapeworm infection of the intestine occurs when people eat raw, undercooked meat like beef, pork or even freshwater fish. Many people affected by tapeworm infestations do not show any symptoms. However, some people may complain of abdominal discomfort, diarrhea and vomiting.
Some of the common species of tapeworms that produce symptoms in humans are:
- taenia saginata (this is also called as beef tapeworm as it is common in beef),
- taenia solium (this is also referred to as pork tapeworm as it is common in pork) and
- diphyllobothrium latum (it is commonly known as fish tapeworm as it is found mainly in fish).
- One of the dangerous varieties of tapeworm is hydatid tapeworm. It is also referred to as Echinococcus granulosis. This variety of tapeworm is commonly found in the intestine of dogs. Humans get infected when they accidentally come in contact with faeces of an infected dog. In such cases they develop hydatid disease. Hydatid disease is a serious and potentially fatal disease.
Body of the Tapeworm
Tapeworm consists of an anchoring organ which is called as scolex. With the help of this scolex the tapeworm is able to attach itself to the wall of the intestine in humans or in animals. The scolex consists of suckers or hooks which help them to firmly lodge themselves in the intestine. The body of tapeworm consists of segments which are also called as proglottids. These proglottids are the reproductive organs of the tapeworm. They consist of both male and female reproductive organs.
Life Cycle of a Tapeworm
Tapeworm needs two hosts in order to complete its life cycle- the intermediate host and the definitive host. The intermediate host is commonly found in sheep, pigs, cattle, goats, horses, camels, wallabies and kangaroos. The definitive host is commonly found in dogs and dingoes.
Development of Hydatid disease in humans
Tapeworm infection of the intestine occurs when people eat raw, undercooked meat like beef, pork or even freshwater fish. People usually become infected by accidentally swallowing the tapeworm eggs that are passed through the faeces of the infected dog. A human acts as an intermediate host in the life cycle of the tapeworm.. The eggs travel through the bloodstream and attach themselves in organs with the help of their suckers or hooks that are present on the scolex. Once they are able to firmly lodge in the organs, they form watery cysts. These watery cysts are full of tapeworm heads. This is known as hydatid disease or echinococcosis. Hydatid disease is not contagious and is not passed by person-to-person contact. In hydatid disease the most commonly affected organ is the liver. Other organs like the kidneys and the brain may also be affected.