Echinococcus Flashcards
Cystic echinococcosis - epidemiology
1 million affected worldwide
Worldwide distribution
Eradicated = NZ, Iceland, Tasmania
Cystic echinococcosis - organism
Echinococcus granulosus
Adult = 3-8mm long
Eggs = 30-35um
Definitive host = canine
Intermediate host = sheep/goat
Cystic echinococcosis - transmission
Ingestion of E granulosus eggs
Echinococcus granulosus - cysts
Lifespan = 5-25 years
Growth rate = 0-5cm per year
2 membranes:
-Laminated membrane
-Germinal membrane producing protoscolices [parasite larvae that will only develop into adults in definitive host = canines]
Cystic echinococcosis - clinical features
70% hepatic cysts
20% lung cysts
10% cysts elsewhere or in multiple sites
Can be asymptomatic or symptoms due to:
-Pressure effection - e.g. RUQ pain with capsular stretching
-Erosion into adjacent organs
-Rupture of cysts = can develop allergic rash, anaphylaxis
Cystic echinococcosis - differential diagnosis
Cystic lesion in liver:
-Simple cyst
-Haematoma
-Abscess
-Cystadenoma
-Cystadenocarinoma
-Necrotic liver mets
Cystic echinococcosis - diagnosis
Imaging:
-WHO classification CE1, 2, 3A/B, 4, 5
-Always do CXR to exclude lung involvement
Serology:
-Sensitivity 80-95% = depends on stage, organ and rupture. Non-viable cysts have low sensitivity
-Specificity 90% = may cross-react with other cestodes
Occasionally = diagnostic puncture
Cystic echinococcosis - CE 1 cyst
Viable
Unilocular
Double line sign
Cystic echinococcosis - CE 2 cyst
Viable
Multiseptated
Daughter cysts
Honey-comb
Rosette
Cystic echinococcosis - CE 3A cyst
Transitional
Cyst with detached membranes
Waterlilly sign = floating membrane within pericyst
Cystic echinococcosis - CE 3B cyst
Transitional
Daughter cysts in solid matrix
Cystic echinococcosis - CE 4 cyst
Inactive
Cyst with heterogenous hypo/hyperechoic contents
No daughter cysts
Cystic echinococcosis - CE 5 cyst
Inactive
Solid cyst with calcified wall
Cystic echinococcosis - management
Depends on type, size and position of cyst
CE1/3A [both unilocular]:
<5cm = albendazole alone 3-6 months
>5cm = PAIR + albendazole
CE2/3B [both multilocular]:
Surgery or other percutaenous procedure with albendazole
CE4/5 [non-viable]:
Watch and wait
Cystic echinococcosis - albendazole MOA
Blocks glucose uptake - kills cysts
Cystic echinococcosis - albendazole use
Small CE1/3A cysts <5cm
Combined with surgery in CE1/3A >5cm and CE2/3B
Cystic echinococcosis - albendazole SE
Hepatitis
Leucopenia
Alopecia [common and reversible]
Cystic echinococcosis - praziquantel MOA
Prevents differentiation of protoscolex into a cyst
Does not penetrate mature cyst = may boost intra-cystic albendazole
Cystic echinococcosis - praziquantel Use
Peri-operatively/procedure
Ruptured cysts
Cystic echinococcosis - praziquantel SE
Nausea
Abdominal pain
Dizziness
Cystic echinococcosis - PAIR
PAIR = puncture-aspiration-injection-reaspiration
-Only hepatic cysts
-Approach through liver parenchyma
-Aspirate tested for bilirubin - to assess if cyst continuous with biliary tree [do not inject scolicidal agent - ethanol or hypertonic saline]
Cystic echinococcosis - PAIR use
CE1/3A cysts >5cm = give albendazole and praziquantel cover
Does not work if daughter cysts present
Cystic echinococcosis - management of other cysts
Lung cysts:
-Surgery - followed by albendazole
Disseminated disease:
-Remove as many cysts as safely as possible
-Long term albendazole
Cystic echinococcosis - control
Definitive host:
-Praziquantel treatment for dogs every 2 months
Community:
-Improved facilities at slaughter house - safe disposal of offal
Vaccine:
-EG95 vaccine for sheep
Alveolar echinococcosis - organism
Echinococcus multilocularis
Alveolar echinococcosis - epidemiology
Definitive hosts = foxes, domestic dogs
Intermediate host = small rodent - voles, marmot, lemmings, hamsters
Hyperendemicity:
-Parts of Germany, France - now expanding across Europe
-China
Alveolar echinococcosis - incubation period
5-15 years
Alveolar echinococcosis - clinical features
Primarily infects liver:
-RUQ pain, weight loss, jaundice, cholangitis
-Unlike CE = primary ifnection of other sites is rare
Infiltration of local organs = kidneys, adrenals, diaphragm, pleura, lungs
Can metastisises elsewhere = spleen, lungs, brain, bone
Alveolar echinococcosis - diagnosis
Imaging [US/CT/MR/PET]:
-Infiltrate growth at margins of lesion
-Necrosis in centre of lesion
-Scattered calcification across lesion
Serology = confirmatory role
Biopsy = if unable to exclude malignancy
Alveolar echinococcosis - management
Radical surgery with albendazole 2 years:
-Solitary liver lesions
-Resection margin
If hepatic complications - biliary obstruction with metastatic disease:
-Palliative surgery with lifelong albendazole
Metastatic disease but no hepatic complications:
-Lifelong albendazole
Liver transplant
