Echinococcus granulosus
Echinococcus granulosus ADULT MORPHOLOGY - small tapeworm - 3-6 mm long consists of scolex, neck, immature proglottid, mature proglottid, and gravid proglottid
Echinococcus granulosus Hydatid disease Cosmopolitan Mediterranean countries Russian federation China North and East Africa Australia South America North America: Deep South and Far West
Carnivore Humans Herbivore
10-30 scolices per brood capsule
Pathogenesis Hydatid cyst Slow growth Asymptomatic for years Up to 20 years (unless in nervous system) Pathology depends on Location Size How many
Pathogenesis Crowds host tissues Destroys tissues-replaces with cyst Grows continuously 15 quarts of fluid Millions of scolices Rupture of the cyst fatal Anaphylactic shock hydatid fluid (death) In most herbivores, cysts do not keep growing
Unilocular hydatid cyst in the lung Note pressure effects exerted by cyst that crowds and destroys lung tissue
Hydatid Cyst
Diagnosis Physical imaging MRI CT scan Ultrasound X-ray Serodiagnosis
Hydatid Cyst of Echinococcus granulosus
Treatment Surgery Recurrence Mebendazole Preoperative chemotherapy-albendazole Protoscolicidal compounds Ethanol Saline Formalin Recurrence 50% Undetected cysts Inadequate removal Mebendazole 48% of cysts
Epidemiology How do people get infected? How do eggs get into environment? How do we ingest them?
Epidemiology Human-Dog Herbivores: Sheep, goats, camels, rabbit Sheep raising areas Offal
Epidemiology Human-Dog contact
Epidemiology Human-wildlife contact
Echinococcus granulosus
Complex Echinococcus granulosus comprises multiple species Life cycle patterns Host specificity Development Rate Antigenicity Transmission dynamics Chemotherapeutic drug response Pathology
Control Sheep vaccine successful
Echinococcus multilocularis
Life Cycle of Echinococcus multilocularis 1. Adult tapeworm occurs in intestine of foxes. Dogs, cats, and coyotes can also serve as definitive hosts. Adult is small - 1-2 mm long
Echinococcus multilocularis Alveolar hydatid cyst in a mouse - cyst metastasizes from the liver to fill the body cavity
Alveolar Hydatid Cyst
Echinococcus multilocularis Liver Cyst multilocular hydatid External budding Extend processes throughout tissues Cirrhosis of liver Thinner membrane Metastasis Advanced cases
Echinococcus multilocularis Not easily operable timing Chemotherapy Praziquantel can increase growth Mebendazole and albendazole given throughout the life of the patient. retards growth Not easily treatable
Echinococcus multilocularis Fox tapeworm Europe, Asia, Americas, New Zealand
Echinococcus multilocularis This species has recently been reported in the upper Midwest (North and South Dakota, Minnesota, Iowa, Nebraska, southern Wisconsin, and Indiana). Recently identified in Illinois, Ohio and Missouri.
Epidemiology Increasing in Europe Up to 1980’s only in France, Switzerland, Germany, and Austria Spreading throughout Europe.
Epidemiology Increase in fox infection Increase in human infection Still rare Switzerland and Germany Antirabies vaccines Increased fox abundance Movement of foxes Encroachment on urban areas Contact with domestic dogs
Hymenolepis
Hymenolepis Hymenolepis diminuta Hymenolepis nana Rare in humans 90 cm Model tapeworm Hymenolepis nana “Dwarf tapeworm” 40 mm long Common in humans 97.3% children in Moscow 1% children in SE US Cysticercoid
Hymenolepis nana D A 1 B 2 3 4 C
Pathogenesis and Treatment Similar to Adult species of Taenia Praziquantel
Dipylidium caninum
Dipylidium caninum Most common tapeworm of dogs Cats, humans 2 sets of reproductive organs
Gravid proglottids shed Dog eats flea Infective stage?
Diagnostics
Pathogenesis and Treatment Similar to Adult species of Taenia Praziquantel