Tapeworm infection
Encyclopedia
Tapeworm infestation is the infection of the digestive tract by adult parasitic flatworm
s called cestodes or tapeworms. Live tapeworm larvae (coenuri) are sometimes ingested by consuming undercooked food. Once inside the digestive tract, a larva can grow into a very large adult tapeworm. Additionally, many tapeworm larvae cause symptoms in an intermediate host
. For example, cysticercosis
is a disease of humans involving larval tapeworms in the human body.
Among the most common tapeworms in humans are the pork tapeworm (T. solium), the beef tapeworm (T. saginata
), the fish tapeworm (Diphyllobothrium spp.), and the dwarf tapeworm (Hymenolepis
spp.). Infections involving the pork and beef tapeworms are also called taeniasis. Tapeworms of the genus Echinococcus
infect and cause the most harm to intermediate hosts such as sheep and cattle. Infection with this type of tapeworm is referred to as Echinococcosis
or hydatid disease. Symptoms vary widely, as do treatment options, and these issues are discussed in detail in the individual articles on each worm. With a few notable exceptions like the fish tapeworm, most cestodes that infect humans and livestock are cyclophyllid
s, and can be identified as such by the presence of four suckers on their scolex or head.
and include Southeast Asia
, West Africa
, and East Africa
.
may develop in people with the fish tapeworm. Infection is generally recognized when the infected person passes segments of proglottids in the stool (looks like white worms), especially if a segment is moving.
Rarely, worms may cause obstruction of the intestine
. And very rarely, T. solium larvae can migrate to the brain causing severe headaches, seizures and other neurological problems. This condition is called neurocysticercosis. It can take years of development before the patient has those symptoms of the brain.
. Praziquantel
and albendazole
can also be used.
For example, if a pig is infected with a tapeworm, it may pass eggs or segments (proglottids) of the adult tapeworm through its feces into soil. Each segment contains thousands of microscopic tapeworm eggs. These eggs can be ingested via food contaminated with the feces. Once the eggs have been ingested, they develop into larvae, which can migrate out of the intestines and form cysts in other tissues such as the lungs or liver. This type of infection is not common with beef or fish tapeworms, but can occur with the pork tapeworm — called cysticercosis — and can also occur with dog and sheep tapeworms — called echinococcosis.
Adult tapeworms can measure up to 50 feet (15.2 m) long and can survive as long as 20 years. Some tapeworms attach themselves to the walls of the intestine, where they cause irritation or mild inflammation, while others may pass through to the stool and exit the body.
Unlike other tapeworms, the dwarf tapeworm can complete its entire life cycle — egg to larva to adult tapeworm — in one host. This is the most common tapeworm infection in the world and can be transmitted between humans.
Even while being treated for certain tapeworm infections, reinfection can result from ingesting tapeworm eggs shed by the adult worm into the stool, as a result of insufficient personal hygiene.
Flatworm
The flatworms, known in scientific literature as Platyhelminthes or Plathelminthes are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals...
s called cestodes or tapeworms. Live tapeworm larvae (coenuri) are sometimes ingested by consuming undercooked food. Once inside the digestive tract, a larva can grow into a very large adult tapeworm. Additionally, many tapeworm larvae cause symptoms in an intermediate host
Intermediate host
A secondary host or intermediate host is a host that harbors the parasite only for a short transition period, during which some developmental stage is completed. For trypanosomes, the cause of sleeping sickness, humans are the primary host, while the tsetse fly is the secondary host...
. For example, cysticercosis
Cysticercosis
Cysticercosis refers to tissue infection after exposure to eggs of Taenia solium, the pork tapeworm. The disease is spread via the fecal-oral route through contaminated food and water, and is primarily a food borne disease. After ingestion the eggs pass through the lumen of the intestine into the...
is a disease of humans involving larval tapeworms in the human body.
Common types
Taenia saginata
Taenia saginata, also known as Taeniarhynchus saginata or the beef tapeworm, is a parasite of both cattle and humans, causing taeniasis in humans. Taenia saginata occurs where cattle are raised by infected humans maintaining poor hygiene, human feces are improperly disposed of, meat inspection...
), the fish tapeworm (Diphyllobothrium spp.), and the dwarf tapeworm (Hymenolepis
Hymenolepis
Hymenolepis is a genus of cyclophyllid tapeworms responsible for hymenolepiasis.Species include:*Hymenolepis nana*Hymenolepis diminuta*Hymenolepis microstoma- History :...
spp.). Infections involving the pork and beef tapeworms are also called taeniasis. Tapeworms of the genus Echinococcus
Echinococcus
The genus Echinococcus includes six species of cyclophyllid tapeworms to date, of the family Taeniidae. Infection with Echinococcus results in hydatid disease, also known as echinococcosis....
infect and cause the most harm to intermediate hosts such as sheep and cattle. Infection with this type of tapeworm is referred to as Echinococcosis
Echinococcosis
Echinococcosis, which is often referred to as hydatid disease or echinococcal disease, is a parasitic disease that affects both humans and other mammals, such as sheep, dogs, rodents and horses. There are three different forms of echinococcosis found in humans, each of which is caused by the larval...
or hydatid disease. Symptoms vary widely, as do treatment options, and these issues are discussed in detail in the individual articles on each worm. With a few notable exceptions like the fish tapeworm, most cestodes that infect humans and livestock are cyclophyllid
Cyclophyllidea
Tapeworms of the order Cyclophyllidea are the most important cestode parasites of humans and domesticated animals. All have multiple proglottid "segments," and all have four suckers on their scolex , though some may have other structures as well...
s, and can be identified as such by the presence of four suckers on their scolex or head.
Occurrence
Most occurrences are found in areas which lack adequate sanitationSanitation
Sanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes. Hazards can be either physical, microbiological, biological or chemical agents of disease. Wastes that can cause health problems are human and animal feces, solid wastes, domestic...
and include Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
, and East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
.
Symptoms
Although tapeworms in the intestine usually cause no symptoms, some people experience upper abdominal discomfort, diarrhea, and loss of appetite. AnemiaAnemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
may develop in people with the fish tapeworm. Infection is generally recognized when the infected person passes segments of proglottids in the stool (looks like white worms), especially if a segment is moving.
Rarely, worms may cause obstruction of the intestine
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
. And very rarely, T. solium larvae can migrate to the brain causing severe headaches, seizures and other neurological problems. This condition is called neurocysticercosis. It can take years of development before the patient has those symptoms of the brain.
Treatment
Tapeworms are treated with medications taken by mouth, usually in a single dose. The drug of choice for tapeworm infections is niclosamideNiclosamide
Niclosamide is a teniacide in the anthelmintic family especially effective against cestodes that infect humans...
. Praziquantel
Praziquantel
Praziquantel is an anthelmintic effective against flatworms. Praziquantel is not licensed for use in humans in the UK; it is, however, available as a veterinary anthelmintic, and is available for use in humans on a named-patient basis....
and albendazole
Albendazole
Albendazole, marketed as Albenza, Eskazole, Zentel and Andazol, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved...
can also be used.
Ingestion of eggs
Tapeworm eggs are generally ingested through food, water or soil contaminated with human or animal (host) feces.For example, if a pig is infected with a tapeworm, it may pass eggs or segments (proglottids) of the adult tapeworm through its feces into soil. Each segment contains thousands of microscopic tapeworm eggs. These eggs can be ingested via food contaminated with the feces. Once the eggs have been ingested, they develop into larvae, which can migrate out of the intestines and form cysts in other tissues such as the lungs or liver. This type of infection is not common with beef or fish tapeworms, but can occur with the pork tapeworm — called cysticercosis — and can also occur with dog and sheep tapeworms — called echinococcosis.
Ingestion of larvae cysts in meat or muscle tissue
Tapeworm infection can also be caused by eating raw or undercooked meat from an animal or a fish that has the larval form of the tapeworm cysts in its muscle tissue. Once ingested, the larvae then develop into adult tapeworms in the intestines.Adult tapeworms can measure up to 50 feet (15.2 m) long and can survive as long as 20 years. Some tapeworms attach themselves to the walls of the intestine, where they cause irritation or mild inflammation, while others may pass through to the stool and exit the body.
Unlike other tapeworms, the dwarf tapeworm can complete its entire life cycle — egg to larva to adult tapeworm — in one host. This is the most common tapeworm infection in the world and can be transmitted between humans.
Even while being treated for certain tapeworm infections, reinfection can result from ingesting tapeworm eggs shed by the adult worm into the stool, as a result of insufficient personal hygiene.
See also
- CoenurosisCoenurosisCoenurosis is a parasitic infection that results when humans ingest the eggs of dog tapeworm species Taenia multiceps, T. serialis, T. brauni, or T...
, a parasitic infection in animals and humans caused by ingested eggs of various species of dog tapeworm - Coenurosis in humans
External links
- Taeniasis - by A.D.A.M., Inc.
- Tapeworm Infection - Health in Plain English (with pictures)
- Tapeworm symptoms in humans
- Taenia spp., tapeworm, causative agent of cysticercosis/taenosis: life cycle, health implications at MetaPathogen