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CESTODES Faculty: AGUAZIM SAMUEL, M.D. • Lange Chapter 54 case • 33 year old Eskimo man presenting with abdominal pain, on and off, with pallor and weakness • No other known illnesses noted • He noticed whitish, tissue like particles in his stools recently • Avid sushi lover case case • Impression: Tapeworm infection • Praziquantrel and Iron, B complex vitamins given. • Recovered Platyhelminthes “flatworm”: • are divided into two large classes of parasites: Cestoda (tapeworms) and Trematoda (flukes). • Cestoda (tapeworms): consist of a rounded headed called a scolex and a flat body of multiple segments called proglottids CESTODES/ TAPEWORMS • worldwide distribution • higher incidence in developing countries • 10% in the third world • Pork tapeworm shows a higher incidence SCOLEX There are four medically important cestodes: – Taenia saginata – Taenia solium – Diphyllobothrium latum – Echinococcus granulosus Taenia saginata Disease: Taeniasis Characteristics: Cestode (beef tapeworm). Scolex has four suckers but no hooks. Gravid proglottids have 15—25 uterine branches. Life cycle: • Humans ingest undercooked beef containing cysticerci “larvae”. • Larvae attach to gut wall and become adult worms with gravid proglottids in about 3 months. • Terminal proglottids detach (containing eggs), pass in feces, and are eaten by cattle. • In the gut, oncosphere embryos emerge from the eggs in the cow’s intestine and burrow into blood vessels, and migrate to skeletal muscles, where they develop into cysticerci. Fun Facts • Adult tapeworms can live up to 25 years • Up to 10 m. in length • Contain over 3000 proglottids, each producing up to 50, 000 eggs • But, clinical infection is most often asymptomatic Scolex Can reach a length of 10 meters!!! Gravid proglottids •Beef tapeworm. Scolex has four suckers but no hooks. Gravid proglottids have 15—25 uterine branches. Taenia saginata (Beef Tapeworm) Transmission: • Transmitted by eating raw or undercooked beef. • Humans are definitive hosts; cattle are intermediate hosts. • Occurs worldwide but endemic in areas of Asia, Latin America, and eastern Europe. Pathogenesis: Tapeworm in gut causes little damage. Laboratory Diagnosis: Gravid proglottids visible in stool. Eggs seen less frequently. Treatment: Praziquantel (Ca is lost resulting in paralysis of worm) Prevention: Adequate cooking of beef & proper disposal of human waste. Gravid proglottids Scolex Pork tapeworm: Scolex has four suckers and a circle of hooks. Gravid proglottids have 5—10 uterine branches Taenia solium (Pork Tapeworm) Diseases: Taeniasis and cysticercosis. Characteristics: Cestode (pork tapeworm). Scolex has four suckers and a circle of hooks. Gravid proglottids have 5—10 uterine branches. • • • • Life cycle: see slide 11 !!!! Humans ingest undercooked pork containing cysticerci. Larvae attach to gut wall and develop into adult worms with gravid proglottids in about 3 months. Terminal proglottids detach (containing eggs), pass in feces, and are eaten by pigs. In pig gut, oncosphere embryos burrow into blood vessels and migrate to skeletal muscle, where they develop into cysticerci. Life Cycle of T. saginatum and T. solium Intestinal form of disease if you ingest undercooked meat!! Very Important!!! Cystercercosis if you are infected by fecal contaminated food !!!! Taenia solium (Pork Tapeworm) Transmission: • Taeniasis acquired by eating raw or undercooked pork. • Cysticercosis acquired only by ingesting eggs in fecally contaminated food or water. • Humans are definitive hosts; pigs or humans are intermediate hosts. • Occurs worldwide but endemic in areas of Asia, Latin America, and southern Europe. Pathogenesis: Tapeworm in gut causes little damage. Cysticerci can expand and cause symptoms of mass lesions, especially in brain. Laboratory Diagnosis: Gravid proglottids visible in stool. Eggs seen less frequently. X-rays and Computed tomography (CT) to demonstrates the presence of the cyst in tissue. Taenia solium (Pork Tapeworm) • If humans eat T. solium eggs in food contaminated with human feces, the oncospheres burrow into blood vessels and disseminate to organs (eg, brain, eyes) where they encyst to form cysticerci. Taenia solium (Pork Tapeworm) Treatment: Praziquantel for intestinal worms and for cerebral cysticercosis. Prevention: Adequate cooking of pork. Proper disposal of human waste. CT Scan of Cysticercosis Diphyllobothrium latum (fish tapeworm) Disease: Diphyllobothriasis. Characteristics: • Cestode (fish tapeworm up to 10 meter long). • Scolex has two elongated sucking grooves; no circular suckers or hooks. • Gravid uterus forms a rosette. Oval eggs have an operculum (lidlike opening) at one end. Fish tapeworm: Scolex has two elongated sucking grooves; no circular suckers or hooks Fish tapeworm: Oval eggs have an operculum (lidlike opening) at one end. Diphyllobothrium latum (fish tapeworm) Life cycle: • Humans ingest undercooked fish containing sparganum larvae. • Larvae attach to gut wall and become adults containing gravid proglottids. • Eggs are passed in feces. • In fresh water, eggs hatch and the embryos are eaten by copepods. • When these are eaten by freshwater fish, larvae form in the fish muscle. Copepod Cope-Greek for “oar” Podos-Greek for foot Diphyllobothrium latum (fish tapeworm) Transmission: Transmitted by eating raw or undercooked freshwater fish. Pathogenesis: Tapeworm in gut causes little damage Symptoms: • may be mild, depending on the number of worms. • abdominal discomfort, loss of weight, loss of appetite and some malnutrition. • 40% of D. Latum carriers may have low serum levels of vitamin B12, presumably because of the competition between the host and the worm for dietary vitamin. • A small percentage (0.1% to 2%) of people infected with D. Latum develop clinical signs of vitamin B12 deficiency. • megaloblastic anemia • neurological problems such as numbness and loss of vibration sense. Diphyllobothrium latum (fish tapeworm) Laboratory Diagnosis: Eggs visible in stool. Treatment: Praziquantel. Prevention: Adequate cooking of fish. Proper disposal of human waste. Echinococcus granulosus (dog tapeworm) Disease: Unilateral hydatid cyst disease. Characteristics: • Cestode (dog tapeworm). • Scolex has four suckers and a double circle of hooks. Adult worm has only three proglottids • Multilocularis hydatid cyst disease is caused by Echinococcus Multilocularis Dog tapeworm. Scolex has four suckers and a double circle of hooks. Echinococcus granulosus (dog tapeworm) Life cycle: • Dogs are infected when they ingest the entrails of sheep, eg, liver, containing hydatid cyst. • Adult worms develop in the gut, and eggs are passed in the feces. • Eggs are ingested by sheep (and humans) and hatch larvae in the gut that migrate in the blood to various organs, especially the liver and brain. • Larvae form one large, unilocular hydatid cyst containing many minor pathogen and daughter cysts. Echinococcus MOT: ingeston of eggs E. Multilocularis multilocular, liver Echinococcus granulosus (dog tapeworm) Transmission: ingestion of eggs in food contaminated with dog feces. Pathogenesis: Hydatid cyst is a space occupying lesion. Also, if cyst ruptures, antigens in fluid can cause anaphylaxis. Laboratory Diagnosis: • Serologic tests, eg, indirect hemagglutination. • Pathologic examination of excised cyst. Treatment: Albendazole or surgical removal of cyst. Hymenolepis nana (dwarf tapeworm) most frequently diagnosed cestode infection in theUS small tapeworm infects children Reservoirs: Rodents vague abdominal pain enteritis Diagnosis :eggs DOC: Nicolsamide MOT: INGESTION OF EGGS/ CYSTICERCOID IN INSECTS Spirometra sparganosis MOT: ingest polluted water raw or inadequately cooked flesh of snakes or frogs southeastern region of the United States east Asia (China, Japan, and Korea) southeast Asia (Malaysia, India, and the Philippines) Sparganosis • • • • • • subcutaneous edema Muscles Eyes urogenital system abdominal viscera central nervous system Sparganosis • Treatment Surgical removal of sparganum larvae Praziquantel no available treatment for proliferative sparganosis