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Lecture 2
Trematodes and Cestodes
Question | Answer |
---|---|
Definitive host of Schistosomes | Humans |
Intermediate host of Schistosomes | Snails |
Where do adult Schistosomes inhabit in the human body? | Portal and Mesenteric vessels |
Species of Schistosoma that infect humans | (1) Schistosoma mansoni (2) Schistosoma japonicum (3) Schistosoma haematobium (4) Schistosoma mekongii (5) Schistosoma intercalatum (6) Schistosoma malayi |
Geographic distribution of Schistosoma mansoni | Arabia, Africa, South America, Caribbean |
Geographic distribution of Schistosoma japonicum | Japan, China, Philippines |
Geographic distribution of Schistosoma haematobium | Africa, Middle East |
Geographic distribution of Schistosoma mekongii | Southeast Asia |
Geographic distribution of Schistosoma intercalatum | West and Central Africa |
Geographic distribution of Schistosoma malayi | Penang Peninsula and Malaysia |
Geographic location of 80% of Schistosoma infections worldwide | Sub-Saharan Africa |
(T or F) Each schistosome species and also strains require a specific species of snail intermediate host. | True. Infections in the US cannot be transmitted due to lack of appropriate snail species. |
(T or F) Most Schistosomiasis infections are asymptomatic. | True. |
Bilharzia or Bilharziosis | Clinical presentation of Schistosomiasis |
Three major syndrome of Schistosomiasis infection | (1) Dermatitis (Swimmer's itch) (2) Acute schistosomiasis (Katayama fever) (3) Chronic Schistosomiasis |
Schistosomiasis infection syndrome caused by penetrating cercariae presenting with a papular pruritic rash | Dermatitis (Swimmer's itch) |
Schistosomiasis syndrome occuring when worms have matured and egg deposition begins. Syndrome presents with serum sickness-like syndrome. | Acute schistosomiasis or Katayama fever |
Most common signs and symptoms of Acute schistosomiasis or Katayama fever | (1) Fever (2) Cough (3) Lymphadenopathy (4) Eosinophilia |
Antaomical location of Shistosomiasis haematobium lesions | Bladder and Ureters |
A Schistosomiasis infection syndrome associated with mature worms and heavy egg deposition. The syndrome is characterized by granuloma formation, most commonly in the liver and intestines. | Chronic Schistosomiasis |
Signs and symptoms of Chronic Schistosomiasis | (1) Fatigue (2) Abdominal pain (3) Diarrhea or Dysentery (4) Heptosplenomegaly (5) Hematuria or Hematemesis |
Symmer's Pipestem Fibrosis | Granulomatous response in the liver leading to continuous fibrosis |
Type of samples needed for microscopic detection of Schistosomiasis eggs | Stool or Urine (Schistosomiasis haematobium) |
Diagnosis of Schistosomiasis Infection | (1) Obtain history of travel and contact with water (2) Microscopic egg detection in stool or urine (3) ELISA test for adult worm antigens |
Treatment of all six species of Schistosomiasis | Praziquantel |
Clinical workup of confirmed Schistosomiasis infection | (1) Liver function tests (2) Heaptic and/or urinary tract imaging |
A parasite of fish-eating mammals in the Far East. Humans become infected by consuming under cooked, pickled, or raw fish. Infection associated with increased incidence of cholagiocarcinoma. | Clonarchis sinesis (Chinese liver fluke) |
Intermediate host of clonarchis sinesis | Snails |
Clinical symptoms of Clonorchiasis | (1) Upper right quadrant pain (2) Anorexia (3) Weight loss |
Pathophyisology of Clonorchiasis | Adult Clonarchis sinensis worms inhabit the bile ducts causing localized obstruction and thickening of the bile duct walls. This results in cholangitis and cholangiohepatitis. |
Treatment of choice for Clonorchiasis | Praziquantel |
Liver fluke that primarily infect cats and dogs | Opisthorchiasis |
Geographic distribuation of Opistrhochis felineus | South East Asia |
Geographic distribution of Opistrhochis viverrini | Thailand |
Geographic distribution of Fasciola hepatica | South America, Europe, Africa, China, and Australia |
Liver fluke in humans associated with watercress consumption | Fascioliasis hepatica |
Natural hosts of Fasciola hepatica | Sheep, cattle and sometimes humans |
Clinical signs/symptoms of Fascioliasis | Early infection: (1) Right upper quadrant pain (2) Hepatomegaly (3) Eosinophilia. Later stages of infection: (1) Bile duct obstruction (2) Biliary cirrhosis |
Treatment of choice for Fascioliasis | Triclabendazole |
Common signs/symptoms of intestinal fluke infection | (1) Diarrhea (2) Abdominal pain (3) Signs of malabsorption |
Intestinal fluke found in Southeast Asia and the Far East. Its metacercariae encyst on aquatic plants | Fasciolpsis buski |
Intestinal fluke found in the Nile delta, Far East, and Southeast Asia. Its metacercariae encyst in freshwater or brakish fish. | Heterophyes heterophyes |
Geographic distribution of Paragonimus westermani | Western Africa, Far East, Indian subcontinent, and Central and South America |
Type of trematode that resides in the lung parenchyma. Typically causes infects humans after ingesting undercooked crabs and crayfish. | Paragonimus westermani |
Clinical signs and symptoms of Paragonimiasis | (1) Eosinophilia (2) Productive cough with brownish sputum (3) Intermittent hemoptysis (4) Chronic bronchitis (5) Pleuritic chest pain |
Treatment of choice for Paragonimiasis | Praziquantel and corticosteroids |
Why must corticosteroids be simultaneously be administered with praziquantel for Paragonimiasis? | Dying worms may cause seizures or other neurological complications with neuroparagnimiasis. |
Scolex | Head of a cestode (tapeworm) |
Strobila | Tail of a cestode (tapeworm). Consists of a chain of independent proglottids. |
Intermediate and definitive host of Taenia saginata | Intermediate host: cattle Definitive host: human |
Intermediate and definitive host of Taenia solium | Intermediate host: Pigs, humans, dogs Definitive host: Humans |
Intermediate and definitive host of Diphyllobothrium latum (Fish tapeworm) | Intermediate host: Copepods then fish Definitive host: humans |
Intermediate and definitive host of Hymenolepsis nana (Dwarf tapeworm) | Intermediate host: Humans Definitive host: Humans |
Intermediate and definitive host of Echinococcus granulosus | Intermediate host: Sheep, cattle, humans Definitive host: Dog |
Intermediate and definitive host of Echinococcus multilocularis | Intermediate host: Rodents, humans Definitive host: Dog |
Geographic distribution of Taenia saginata (Beef Tapeworm) infections | Central Asia, Near East, Central and South America |
Mode of human infection by Taenia saginata | Humans infected after consumption of under cooked beef with Taenia saginata cysts. |
Clinical symptoms of Taenia saginata infection | (1) Mild abdominal cramps (2) Malaise |
Treatment of choice for Taenia saginata infection | Praziquantel or niclosamide |
Diagnosis of Taenia saginata | Stool examination for several days for evidence of Taenia saginata eggs and proglottids. |
Geographic distribution of Taenia solium infection | Mexico, Central and South America, Africa, Southeast Asia, India, Philippines, and Southern Europe |
Mode of human tapeowrm infection by Taenia solium | Human infection caused after consumption of under cooked poork with Taenia solium cysts |
Mode of cysticercosis infection | Humans infected by ingesting eggs becoming the intermediate host. Ingested eggs develop into tissue cysts. |
The most common parasitic disease of CNS characterized by seizures, hydrocephalus, parses, meningitis, mental deterioration, and coma. | Neurocysticercosis caused by Taenia solium cysts in the CNS. |
Diagnosis of neurocysticercosis | Radiological evidence of cysts |
Treatment of choice of Taenia solium tapeworm infection | Praziquantel or niclosamide |
Treatment options for Cysticercosis | Albendazole, praziquantel, or surgical removal of cysts |
(T or F) Intraocular cysticercosis can be treated with albendazole or praziquantel. | False. Intraocular cysticercosis should not be treated with drugs. |
Highly endemic areas of Diphyllobothrium latum infection | Europe, North America, Siberia, Japan and Chile |
Cestode infection resulting from ingestion of under cooked fish with cysts. Symptoms include abdominal discomfort, salt craving, and diarrhea. May also cause B12 deficiency anemia. | Diphyllobothrium latum (Fish tapeworm) |
Diagnosis of Diphyllobothrium latum tapeworm infection | (1) Contrast studies of intestine (2) Stool examination for proglottids or eggs |
Treatment of choice for Diphyllobothrium latum tapeworm infection | Praziquantel or niclosamide and Vitamin B12 supplements |
Endemic areas of Hymenolepsis nana tapeworm infections | Asia, Southern and Eastern Euorpe, Central and South America, and Africa |
Mechanism of transmission of Hyemnolepsis nana infections | (1) Human to human (2) Fecal-oral or autoinfection |
Diagnosis of Hymenolepsis nana tapeworm infection | Stool examination for Hymenolepsis nana eggs |
Treatment of choice for Hymenolepsis nana tapeworm infection | Praziquantel or niclosamide |
Mechanism of human infection by Echinococcosis | Humans are inadvertent intermediate hosts, ingest eggs by contamination with feces canines infected with the tapeworm. |
Most common anatomical sites of hydatid cysts of Echinococcus granulosus | Liver (50-70%) and lungs (20-30%) |
Symptoms of Hydatid cyst disease | (1) Mass effects due to enlargin cysts (2) Bacterial infections secondary to obstruction (3) Allergic reaction ot parasite antigens |
Where do new Echinococcus granulosus larvae (scolices) develop? | Larva form a central cyst with a germinal layer from which new larvae (scolices) develop. Cysts can rupture and disseminate scolices, seeding other organs. |
Treatment of choice for Hydatid cyst disease | Albendazole or mebendazole. Surgical resection of cyst may be possible, but must take care not to rupture the cyst. |
Geographic distribution of Echinococcus multilocularis alveolar cyst disease | Europe, Asia, and North America |
Most common anatomical site of Alveolar cyst disease | Cysts are usually found in the liver. |
Treatment of choice of Alveolar cyst disease | Surgical removal and adjunct albendazole therapy |