Echinococcus granulosus

Hydatid diseaseHydatid disease CosmopolitanCosmopolitan –Mediterranean countries –Russian federation –China –North and East Africa –Australia –South America –North America: Deep South and Far West

Echinococcus granulosus ADULT MORPHOLOGY - small tapeworm mm long consists of scolex, neck, immature proglottid, mature proglottid, and gravid proglottid

Carnivore Herbivore Humans

10-30 scolices per brood capsule

Pathogenesis Hydatid cystHydatid cyst Slow growthSlow growth Asymptomatic for yearsAsymptomatic for years Up to 20 years (unless in nervous system)Up to 20 years (unless in nervous system) Pathology depends onPathology depends on –Location –Size –How many

Pathogenesis Crowds host tissuesCrowds host tissues Destroys tissues-replaces with cystDestroys tissues-replaces with cyst Grows continuouslyGrows continuously –15 quarts of fluid –Millions of scolices Rupture of the cyst fatalRupture of the cyst fatal –Anaphylactic shock hydatid fluid (death) In most herbivores, cysts do not keep growingIn 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 imagingPhysical imaging –MRI –CT scan –Ultrasound –X-ray SerodiagnosisSerodiagnosis

Hydatid Cyst of Echinococcus granulosus

Treatment SurgerySurgery –Preoperative chemotherapy-albendazole –Protoscolicidal compounds EthanolEthanol SalineSaline FormalinFormalin RecurrenceRecurrence –50% –Undetected cysts –Inadequate removal MebendazoleMebendazole –48% of cysts

Epidemiology How do people get infected?How do people get infected? How do eggs get into environment?How do eggs get into environment? How do we ingest them?How do we ingest them?

Epidemiology Human-DogHuman-Dog Herbivores: Sheep, goats, camels, rabbitHerbivores: Sheep, goats, camels, rabbit Sheep raising areasSheep raising areas OffalOffal

Epidemiology Human-Dog contactHuman-Dog contact

Epidemiology Human-wildlife contactHuman-wildlife contact

Echinococcus granulosus

Complex Echinococcus granulosus comprises multiple speciesEchinococcus granulosus comprises multiple species –Life cycle patterns –Host specificity –Development Rate –Antigenicity –Transmission dynamics –Chemotheraputic drug response –Pathology

Control Sheep vaccine successfulSheep 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 mm long

Echinococcus multilocularis Alveolar hydatid cyst in a mouse - cyst metastasizes from the liver to fill the body cavity

Alveolar Hydatid Cyst

LiverLiver Cyst multilocular hydatidCyst multilocular hydatid External buddingExternal budding Extend processes throughout tissuesExtend processes throughout tissues Cirrhosis of liverCirrhosis of liver Thinner membraneThinner membrane MetastasisMetastasis –Advanced cases Echinococcus multilocularis

Not easily operableNot easily operable –timing ChemotherapyChemotherapy –Praziquantel can increase growth –Mebendazole and albendazole given throughout the life of the patient. retards growthretards growth Not easily treatableNot easily treatable

Echinococcus multilocularis Fox tapewormFox tapeworm Europe, Asia, Americas, New ZealandEurope, 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 EuropeIncreasing in Europe Up to 1980’s only in France, Switzerland, Germany, and AustriaUp to 1980’s only in France, Switzerland, Germany, and Austria Spreading throughout Europe.Spreading throughout Europe.

Epidemiology Increase in fox infectionIncrease in fox infection Increase in human infectionIncrease in human infection –Still rare Switzerland and GermanySwitzerland and Germany –Antirabies vaccines –Increased fox abundance –Movement of foxes –Encroachment on urban areas –Contact with domestic dogs

Hymenolepis

Hymenolepis Hymenolepis diminutaHymenolepis diminuta –Rare in humans –90 cm –Model tapeworm Hymenolepis nanaHymenolepis nana –“Dwarf tapeworm” 40 mm long –Common in humans –97.3% children in Moscow –1% children in SE US Cysticercoid

Hymenolepis nana A B C D

Pathogenesis and Treatment Similar to Adult species of TaeniaSimilar to Adult species of Taenia PraziquantelPraziquantel

Dipylidium caninum

Most common tapeworm of dogsMost common tapeworm of dogs Cats, humansCats, humans 2 sets of reproductive organs2 sets of reproductive organs

Gravid proglottids shed Dog eats flea Infective stage?

Diagnostics

Pathogenesis and Treatment Similar to Adult species of TaeniaSimilar to Adult species of Taenia PraziquantelPraziquantel