Microbiology
Summary
The cestodes, commonly known as tapeworms, include Taenia solium and Taenia saginata, Diphyllobothrium latum, and Echinococcus granulosus. T. solium and T. saginata infections are caused by ingesting cysts or larvae in undercooked meat, usually from infected pigs or cattle, respectively. T. solium can be differentiated by the presence of hooks on its proglottid. Additionally, ingestion of T. solium eggs can lead to neurocysticercosis, where parasites travel to the brain, forming cyst-like brain lesions which may result in seizures or hydrocephalus. Diseases resulting from the Taenia genus can be treated with praziquantel, and in the case of neurocysticercosis, albendazole is also required.
Diphyllobothrium latum, or the fish tapeworm, is transmitted through consumption of uncooked or undercooked fish. This tapeworm can cause diarrhea and potentially lead to a vitamin B12 deficiency, resulting in megaloblastic anemia. Echinococcus granulosus, or sheep tapeworm, is contracted by ingesting eggs found in dog feces. This tapeworm commonly leads to a liver abnormality known as hydatid cysts. These cysts may rupture, causing an anaphylactic reaction and an acute abdomen.
Lesson Outline
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FAQs
Cestodes, commonly known as tapeworms, are a classification of parasitic worms within the phylum Platyhelminthes. These worms are segmented, flat, ribbon-like organisms that inhabit the intestines of their host.
Taenia solium (the pork tapeworm) and Taenia saginata (the beef tapeworm) are species of cestodes. Humans can become infected by consuming raw or undercooked meat contaminated with eggs or larvae, leading to taeniasis.
Neurocysticercosis is a specific form of cysticercosis (infection with the pork tapeworm's larvae) where the brain and central nervous system are affected. It is generally caused by ingestion of Taenia solium eggs, often through contaminated food or water, followed by the eggs hatching and larvae invading the central nervous system.
Diphyllobothrium latum (fish tapeworm) and Echinococcus granulosus (dog tapeworm) are both species of cestodes. Infection generally occurs when people ingest improperly cooked or raw fish (for Diphyllobothrium latum) or come into contact with infected dogs or dog feces (for Echinococcus granulosus).
Praziquantel and albendazole are both antiparasitic drugs commonly used to treat infections caused by cestodes. Praziquantel is especially effective against most species of adult tapeworms present in the intestines, such as Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm), and Diphyllobothrium latum (fish tapeworm). Albendazole is particularly beneficial in treating cysticercosis and echinococcosis, conditions caused by the larval forms of Taenia solium and Echinococcus granulosus, respectively.
