Types of Tapeworm Infections in Humans

Tapeworms are segmented flatworms that live in the intestinal tracts of their hosts. Tapeworm infections occur when the host ingests water or eats meat infected with tapeworm larvae. There are several different types of tapeworm that cause infections in humans

Beef Tapeworm

A beef tapeworm (Taenia saginata) is a segmented flatworm that looks like a ribbon. This infection is caused when cattle feed is infected with human fecal matter, the larvae enters a cow's muscle tissue and humans ingest the infected meet. Tapeworm infections are endemic in the United States (US), Mexico, Africa, Europe and Latin America. Symptoms of a beef tapeworm infection include nausea, vomiting, lack of appetite, abdominal pain and weight loss.

Dwarf Tapeworm

Dwarf tapeworms (Hymenolepis nana), often called rat tapeworms, cause most of the tapeworm infections in humans. Tapeworm infections are distributed across India, Egypt, Latin America and rural areas in the southeastern US. Dwarf tapeworm infections typically occur when food sources are contaminated by the feces of infected rats. Dwarf tapeworms are smaller than other types of tapeworm, growing to be only about 2 inches in length. Symptoms of a dwarf tapeworm infection include abdominal pain and diarrhea filled with mucus or blood.

Pork Tapeworm

Pork tapeworm (Taenia solium) are large flatworms that can grow up to 30 feet long. Tapeworm infections are caused by eating undercooked pork infected with tapeworm larvae. These infections are common in Mexico, India, Africa, Eastern Europe and Asia. Pork tapeworm infections typically don't cause any symptoms, but some people experience mild gastrointestinal (GI) distress, such as abdominal pain or nausea.

Fish Tapeworm

Fish tapeworm (Diphyllobothrium latum) can also grow up to 30 feet long and typically infect humans, bears and cats. Fish tapeworm infections occur when the host eats a raw fish ingested with the larvae. Fish tapeworm infections occur in regions where freshwater fish is a dietary staple, such as North and South America, western Russia, Eastern Europe, Africa and the Baltics. Some infected individuals suffer from nausea, diarrhea, vomiting, abdominal pain and, occasionally, intestinal blockage. The fish tapeworm competes with the host to absorb the vitamin B12 in the small intestine. This causes many infected individuals to become vitamin B12 deficit and suffer from pernicious anemia. Symptoms of pernicious anemia include fatigue and a tingling or numb sensation in the limbs.

Dog Tapeworm

Dog tapeworm (Dipylidium caninum) causes a majority of infections in dogs and cats. Dog tapeworm spreads when a flea ingests infected feces. Humans contract the dog tapeworm infection when they accidentally swallow an infected flea. Dog tapeworm infections typically cause no symptoms, but individuals with low immunity sometimes show signs of fatigue, weakness and GI discomfort.

References

http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mmed&part=A4668
http://www.cdc.gov/ncidod/dpd/parasites/hymenolepis/factsht_hymenolepis.htm
http://www.merck.com/mmhe/sec17/ch196/ch196p.html
http://www.nlm.nih.gov/medlineplus/ency/article/001375.htm
http://www.cdc.gov/ncidod/dpd/parasites/dipylidium/factsht_dipylidium.htm