Tapeworms In Humans. Symptoms. Treatment. Life Cycle. Prevention

By Raj | Nov 22, 2007

Tapeworms are long, flat, ribbon shaped, intestinal worms found in the intestines of vertebrates. The term tapeworm is commonly restricted to members of the class Cestoidea. The tapeworms (cestodes) Taenia saginata (beef tapeworm) and Taenia solium (pork tapeworm) are of significance to human being as taeniasis occurs when raw or undercooked, unfrozen beef or pork are eaten. Of note is the life-threatening condition called cysticercosis (cysticercus disease), a disease caused by encystment (trapped bubbles) of cysticercus larvae of tapeworms in subcutaneous, muscle, or central nervous system tissues. Cysticercosis is typically developed in swine and cattle, producing measly pork and beef while in humans, it results from the hatching of the eggs of Taenia solium in the intestines or by accidental ingestion of eggs from human feces. Encystment in the brain may cause serious nervous damage and can be life threatening and encystment in the eye (usually the rear chamber) may cause ophthalmic damage.

Synonyms

Cestodes.

Epidemiology

Both species viz., Taenia saginata and Taenia solium are worldwide in distribution. Taenia solium is more prevalent in poorer communities where humans live in close contact with pigs and eat undercooked pork.

Echinococcus, another genus of the tapeworms, which causes hydatid disease, is found in sheep herders living closely with their infected dogs.

Fish tapeworms are found in the coastal region/in the regions of fish consumption.

Symptoms

Beef tapeworm infections produce only mild symptoms that may include diarrhea, abdominal pain and weight loss. Pork tapeworm infections generally produce no symptoms. Another sign of having tapeworms can be if pieces of the tapeworm break apart (proglottids) and come out through the feces. Cysticercosis, however, can cause muscle pain, weakness and fever. If the central nervous system is involved, it can also cause epilepsy or inflammation of the brain and the membranes around it. Severe tapeworm infection in humans is also known to cause anemia due to the lack of vitamin B-12, which the tapeworm absorbs through the lining of the gut.

Diagnosis

Eggs and proglottids can be seen in stool samples by microscopic examination. Cysticercosis is diagnosed by examining the muscles, brain or the part involved with a CT or MRI scan that can show the cysts. Blood tests for antibodies can confirm the diagnosis.

Life Cycle. How Do You Get It?

Humans are the only definitive hosts (containing the adult, sexually-reproducing stage) for Taenia saginata and Taenia solium. Eggs or gravid proglottids are passed with feces. The eggs can survive for days to months in the environment. Cattle and pigs become infected with Taenia saginata and Taenia solium respectively by ingesting vegetation contaminated with eggs or gravid proglottids. In the animal’s intestine, the hexacanths hatch, invade the intestinal wall, and migrate to the striated muscles, where they develop into cysticerci. A cysticercus can survive for several years in the animal. Humans become infected by ingesting raw or undercooked infected meat. In the human intestine, the cysticercus develops over two months into an adult tapeworm, which can survive for years. The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine. The adult parasitic worms produce proglottids which mature, become gravid, detach from the tapeworm, and migrate to the anus or are passed in the stool. The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces.

If this cycle is short circuited by a human by directly ingesting the eggs instead of a pig (which can occur in regions with poor sanitation), cysticerci can develop in human flesh too which may form large cysts (bubbles), often in the brain, which can be life threatening.

Contagious?

Not that severe, but yes in poor sanitary conditions where eggs can be ingested and get infected instead of getting infection from the meat.

Prevention and Treatment

Tapeworm infection may be prevented by thoroughly cooking meat/fish until juices run clear and the centers are no longer pink. This ensures that any tapeworm cysts in the meat/fish are destroyed.
Always avoid rare meat/fish. The heat it takes to properly cook meat/fish kills tapeworms.
Ensure clean drinking water.
Ensure good personal hygiene and eating habits. Keep hands always clean. Trim nails. Wash hands before eating or preparing food. Wash hands after a toilet visit. Any anti-bacterial soap will usually insure a worm-free existence. Emphasize the importance of washing hands to children.
Discourage thumb sucking/nail biting of children.
Deworm regularly or as directed by your primary physician.

Medications

Conventional drug options are quinacrine hydrochloride (atabrine hydrochloride) or niclosamide. Tapeworm cysts will require two separate drugs, praziquantel and albendazole. Talk to your doctor for more information and appropriate dosages and intervals.