All tapeworms belong to the phylum platyhelminthes in the class cestoda. The class cestoda consists of about 5000 species. All are endoparasitic tapeworms. Most of them need at least 2 hosts. The definitive hosts of the adult tapeworms are usually vertebrates while the intermediate hosts are invertebrates. Tapeworms are adapted to the parasitic lifestyle. Their bodies may grow up to 12 meters. They do not have cilia but they have a tough outer tegument. The knob-shaped head, called scolex contains the hooks and suckers which are used to attach onto the host.
There are a few tapeworms that are common to the human beings. Among of them is the beef tapeworm or its Latin name is Taenia Saginatta. This parasite has cattle or related animals as its main intermediate hosts. The larval form in these animals is a cysticercus in the muscles and heart. These are infected by ingestion of the eggs of the tapeworm, shed from faeces of the definitive hosts such as man. Man is infected by ingestion of undercooked or raw meat. The bladder wall of the cysticercus will be digested in the intestine to release the scolex of the parasite. This attaches to intestinal wall and grows into the mature adult worm. Infection may be accompanied by broad range non-specific symptoms such as abdominal pain, digestive disturbances, excessive appetite or loss of appetite, weakness or loss of weight.
The next type of tapeworms is the pork tapeworm or in Latin, Taenia Solium. This parasite has pigs as the intermediate hosts. However, man may also act as an intermediate host for this parasite as well as being infected with the adult tapeworms. Infection with the larval form of Taenia Solium may have severe consequences. In man, the larvae mainly develop in the subcutaneous tissues, but infection in both Central Nervous System (CNS) and ocular tissues are also very common. Infection of the CNS may cause severe pain, paralysis, optical and psychic disturbances, and epileptic convulsions, mainly due to mechanical pressure as the larvae develop. Later, there may be loss of consciousness and even death.
Next is broad fish tapeworm or its Latin name is Diphyllobothrium Latum. This type of tapeworm is an intestinal tapeworm which possesses a scolex with 2 bothria unlike the typical 4 suckers seen on the Taenia species. The worm is widely distributed in sub-arctic region. The adult broad fish tapeworm may grow up to between 12 and 15 meters and grows continuously in its host throughout its life. The definitive hosts for this worm are humans, cats, and other fish eating mammals including seals. The symptoms associated with Diphyllobothrium Latum may be absent or including diarrhea, abdominal cramps, and distention and typically start 8-10 days after ingestion. The tapeworm may also cause a vitamin B12 deficiency which may lead to anaemia in a small percentage of people.
There are many other tapeworms besides the tapeworms mentioned above. However, most of them are less common compared to these three types of tapeworms. Those who were infected by these tapeworms are advised to take the treatment as quickly as possible.