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Lecture 2

Trematodes and Cestodes

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
Created by: UVAPATH4