Such tape worms in question are: the dwarf tapeworm, the dog tapeworm and Echinococcus multilocularis. Such names sound so scary huh? What are their effects?
Hymenolepis nana (dwarf tapeworm)
Hymenolepis nana is found worldwide, commonly in the tropics. Multilocular Hydratid disease occurs primarily in hunters and is endemic in northern Europe, siberia, and the western provinces of Canada. Unilocular Hydratid Cyst Disease is found primarily in shepherds living in the Mediterranean region, the Middle East and Australia.
It is only 2-3cm in length. Scolex has round form and contains suckers and hooks. Its neck is very long and thick. Strobila has 200 proglottides. the uterus has an excretory ostium. Eggs are released from it into the feces. Transmission is through the fecal-oral (by the ingestion of eggs from contaminated food or water) route.
H.nana is different from other tapeworms, because its eggs are directly infectious for humans; i.e ingested eggs can develop into adult worms without an intermediate host. Within the duodenum, the eggs hatch and differentiate into cysticercoid larvae and then into adult worms. Gravid proglottids detach, disintegrate, and release fetilized eggs. The eggs either pass in the stool or can reinfect the small intestine (autoinfection). In contrast to infection by other tapeworms, where only one adult worm is present, many H.nana worms (sometimes hundreds) are found.
It is asymptomatic, but diarrhea and abdominal cramps may be present. Diagnosis can be proven by observing eggs in stool. The characteristic feature of H.nana eggs is the 8-10 polar filaments lying between the membrane of the 6-hooked larva and the outer shell. There are so many suggestions to the treatment therapy of Hymenolepsis nana. One suggestions recommends Acranil drug in tablets taken orally (depending on doctor's prescription) while others recommend three drugs which are: Praziquantel, niclosamide and paromomycin. Nitrazoxamide has been recently discovered as another treatment option. Prevention consists of good personal hygiene and avoidance of fecal contamination of food and water.
Echinococcus granulosus (dog tapeworm)
It is found primarily in shepherds living in the Mediterranean region, the Middle East, Australia and USA (western states). The worm is up to 3-5mm. Scolex has suckers and hooks. Its neck is short, strobila has 3-5 proglottids. Posterior segment (mature) is the largest and contains uterus with the haustrums, genital pore situated in the back of the proglottid. Transmission is through the fecal oral route by the ingestion of eggs from contaminated food or water.
Dogs are the most important definitive hosts. The intermediate hosts are usually sheep. Humans are almost always dead-end intermediate hosts. Worms in the dog's intestine liberate thousands of eggs, which are ingested by sheep (or humans). The oncosphere embryos emerge in the small intestine and migrate primarily to the liver but also to the lungs, bones, and brain. The embryos develop into large fluid-filled hydatid cysts, the inner germinal layer of which generates many protoscoleces within "brood capsules". The outer layer of the cyst is thick, fibrous tissue produce by the host. The life cycle is completed when the entrails (for example liver containing hydatid cysts) of slaughtered sheep are eaten by dogs.
Many individuals with hydatic cysts are asymptomatic, but liver may cause hepatic dysfunction. Cysts in the lungs can erode into a bronchus, causing bloody sputum, and cerebral cysts can cause headache and focal neurologic stings. If the cysts ruptures spontaneously or during trauma or surgical removal, life-threatening anaphylaxis can occur (the cyst fluid contains parasite antigens, which can sensitize the host). Diagnosis may be done by X-ray, observation of eosinophilia and serologic tests. Prevention of human disease involves not feeding the entrails of slaughtered sheep to dogs.
Echinococcus multilocularis
It is found in northern Europe, siberia, Canada (western provinces), the USA (North and South Dakota, Minnesota, and Alaska). Many of the features of this organism are the same as those of E.granulosus, but the definitive hosts are mainly foxes and the intermediate hosts are various rodents. Humans are infected by accidental ingestion of food contaminated with fox feces. The disease occurs primarily in hunters and trappers. Within the human liver, the larvae form multiloculated cysts with few protoscoleces. No outer fibrous capsule forms, so the cysts continue to proliferate, producing a honeycomb effect of hundreds of small vesicles (without fluid). The clinical picture usually involves jaundice and weight loss. The prognosis is poor and hence surgical removal may be feasible.
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