- Slides: 17
Tapeworm Infection -It is the infection of the digestive tract by adult parasitic flatworms called cestodes or tapeworms. -It is caused by ingesting food or water contaminated with tapeworm eggs or larvae cysts. -Tapeworm larvae develop into adult tapeworms in the intestines (intestinal tapeworm infection). However, some tapeworms can also migrate outside the intestines and form cysts in body tissues and organs (invasive tapeworm infection). -Intestinal tapeworm infections are usually mild, but invasive tapeworm infections can cause serious complications.
An adult tapeworm consists of a head, neck and chain of segments called proglottids which contain eggs. An intestinal tapeworm head adheres to the intestine wall, and the proglottids grow and produce eggs. Adult tapeworms can live for up to 20 years in a host.
Common types The most common types of tapeworm infections in humans are: -Pork tapeworm (Taenia solium) -Beef tapeworm (Taenia saginata) -Dwarf tapeworm (Hymenolepis nana) -Fish tapeworm (Diphyllobothrium latum) Most occurrences are found in areas which lack adequate sanitation and include Southeast Asia and East Africa.
Transmission 1 -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: egg bearing parts) 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 either grow to adult worm in the intestine (Taeniasis) or these larava can migrate out of the intestines and form cysts in other tissues such as the lungs or liver or the brain. This type of infection is not common with beef or fish tapeworms, but can occur with the pork tapeworm — causing what is called Cysticercosis — (i. e) For the pork tapeworm only, people who ingest the eggs can become an intermediate host.
Cont. Transmission Ingestion of larvae cysts in meat or muscle tissue -Untreated infected human waste when released into the environment, the eggs may be ingested by intermediate hosts, such as pigs, cattle, or (in the case of fish tapeworms) small crustaceans, which are in turn ingested by fish. The eggs hatch into larvae in the intermediate host. The larvae invade the intestinal wall and are carried through the bloodstream to skeletal muscle and other tissues, where they form cysts. -Eating raw or undercooked meat from an animal or a fish that has the larval of the tapeworm in form of cysts in its muscle tissue lead to tapeworm infection. -Once ingested, the larvae is released , and then develop into adult tapeworms in the intestines of the human host. Adult tapeworms can measure up to 50 feet 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.
Symptoms Intestinal tapeworms in the intestine usually cause no symptoms, some people experience the following: -Nausea -Weakness -Loss of appetite -Abdominal pain -Diarrhea -Weight loss and inadequate absorption of nutrients from food -Occasionally, a person with a tapeworm can feel a piece of the worm move out through the anus or see part of the ribbon-like tapeworm in stool. -The fish tapeworm (Diphyllobothrium latum) can cause anemia because it absorbs vitamin B 12, which is necessary for red blood cells to mature.
If tapeworm larvae have migrated out of the intestines and formed cysts in other tissues, as in the brain and the tissues covering the brain (meninges) it will cause cysticercosis and result in neurological symptoms as: Headaches , -confusion -Seizures -Fever -Cystic masses or lumps -Allergic reactions to the larvae P. S. : It can take years of development before the patient has those symptoms of the brain. -Rarely, cysts develop in the eyes, sometimes causing blindness, or in the spinal cord, sometimes causing muscle weakness or paralysis.
Diagnosis -Diagnoses of intestinal tapeworm infection is microscopic identification to check for eggs or tapeworm segments in the feces. Because the eggs and segments are passed irregularly, the lab may need to collect two to three samples over a period of time to detect the parasite. -Eggs are sometimes present at the anus, so the doctor may use the "Scotch tape test, " in which a piece of transparent tape is pressed to the anus to collect eggs for microscopic identification. -In people with cysticercosis, cysts in the brain or other tissues can be seen using computed tomography (CT) or magnetic resonance imaging (MRI). Blood tests for antibodies to the pork tapeworm may also be helpful.
Prevention 1 -The first line of defense against tapeworms is thoroughly cooking meat and freshwater fish. 2 -Prolonged freezing can also kill cysts. Thus, freshwater fish should not be served as sushi, and should be eaten only after it has been cooked, or properly froze(Smoking and drying do not kill cysts). 3 -Another line of defense is careful evaluation of meat and fish by trained inspectors. As cysts are visible in infected meat. 4 -Adequate treatment of human waste interrupts the life cycle and thus helps prevent cysticercosis
Treatment Tapeworms are treated with medications taken by mouth, usually in a single dose. The drug of choice for tapeworm infections is niclosamide. Praziquantel is also effective , and albendazole (mainly for cerebral cysticercosis) are also being used
Niclosamide Mechanism of action Niclosamide uncouples oxidative phosphorylation in the tapeworm As it inhibits the mitochondrial A laxative should be taking before and during drug administration to avoid disintegration of died worm and the release of the eggs with increasing possibility of cycticercosis anaerobic phosphorylation of ADP to ATP. Adverse Effects The medication can have side effects such as abdominal pain, anorexia, diarrhea, and emesis. Rarely, dizziness, skin rash, drowsiness, perianal itching, and an unpleasant taste.
Praziquantel Mechanism of action It increases the permeability of the membranes of parasite cells for calcium ions. The drug thereby induces contraction of the parasites resulting in paralysis in the contracted state. The dying parasites are dislodged from their site of action in the host organism and may enter systemic circulation or may be destroyed by host immune reaction (phagocytosis).
n Side effects n The majority of side-effects develop due to the release of the contents of the parasites as they are killed and the consequent host immune reaction. Drowsiness , dizziness, headache, and malaise fatigue, and vertigo have also been seen. Almost all patients with cerebral cysticercosis experience CNS side effects related to the cell-death of the parasites (headache, worsening of preexisting neurological problems, seizures). These side effects may be life-threatening and can be reduced by coadministration of corticosteroids. It is strongly recommended that all patients with cerebral cysticercosis are hospitalized during treatment. Approximately 90% of all patients have abdominal pain or cramps with or without nausea and vomiting. Urticaria, rash, and pruritus. Fever, sweating, various cardiac arrhythmias, and hypotension n n
Albendazole Mechanism of Actions: n n n Albendazole and its metabolite albendazole sulfoxide are thought to act by inhibiting microtubule synthesis in the worm , thus irreversibly impairing glucose uptake. As a result, parasites are immobilized or die slowly, and their clearance may not be complete until several days after treatment. Albendazole also has been shown to inhibit the enzyme fumarate reductase, which is helminth-specific. This action may be considered secondary to the effect on the microtubules due to the decreased absorption of glucose. This action occurs in the presence of reduced amounts of nicotinamide-adenine dinucleotide in reduced form (NADH), which is a coenzyme involved in many cellular oxidationreduction reactions. Patients being treated for neurocysticercosis should receive appropriate steroid anticonvulsant therapy as required. Oral or intravenous corticosteroids should be considered to prevent cerebral hypertensive episodes during the first week of treatment .
Adverse Reactions n Albendazole may cause dizziness, headache, fever, nausea, vomiting, or temporary hair loss. n In rare cases it may cause persistent sore throat, severe headache, seizures, vision problems, yellowing eyes or skin, dark urine, stomach pain, mental/mood changes. n CBC and hepatic functions have to be obtained regularly in patients receiving Albendazole. n The drug, which is teratogenic and embryotoxic (even do not become pregnant for one month after taking this drug).
Treatments for invasive tapeworm infection n n Treating an invasive infection depends on the location and effects of the infection. Anthelmintic drugs. Albendazole can shrink some tapeworm cysts. Monitoring the cysts periodically using ultrasound or X-ray (to be sure the drug is effective )is needed. Anti-inflammatories. Anti-epileptic therapy. Shunt placement. One type of invasive infection cause too much fluid on the brain, called hydrocephalus. Placing a permanent shunt, or tube, in the head of the patient to drain the fluid is required. Surgery. Whether cysts can be removed surgically depends on their location and symptoms. Those that develop in the eyes are typically removed, since they can eventually threaten organ function.