Echinococcus multilocularis: Difference between revisions

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Echinococcus multilocularis
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* Cestode in the [[Echinococcus]] family
  
* Cestode in the [[Echinococcus]] family
  +
*Disease is caused by the larval form
  +
  +
=== Life Cycle ===
  +
  +
* Definitive hosts are canid carnivorous animals, including urban coyotes
  +
* Eggs contaminate the environment, including produce
  +
** They are infective after a few days, and are viable for up to 16 months at 4ºC
  +
* Intermediate hosts (metacestode) are rodents, possibly pigs, and and incidentally humans
  +
* Intermediate host is eaten by the definitive host, completing the life cycle
  +
  +
=== Epidemiology ===
  +
  +
* Estimated 18,000 cases annually
  +
* Worldwide in the northern hemisphere
  +
** Most cases in China (90%), followed by Japan and Russia
  +
** Rare in North America
  +
* Within Canada:
  +
** Associated with arctic foxes and wolves
  +
** Alberta has highest number of cases, with 19 cases from 2013 to 2021
  +
** 0 to 3 case reports in other provinces
   
 
==Clinical Manifestations==
  
==Clinical Manifestations==
   
−
*Causes alveolar echinococcosis
 +
*Causes '''alveolar echinococcosis'''
  +
*Incubation period [[Incubation period range::5 to 15 years]]
⚫
*Presents as a metastatic malignancy of unknown primary
  
  +
*Vague abdominal pain may precede diagnosis by years
⚫
*May also mimic hepatic carcinoma, cirrhosis, and tuberculosis
  
  ⚫
*Presents as a metastatic malignancy of unknown primary, mot commonly with malaise, weight loss, and right upper quadrant discomfort
⚫
*Main treatment is surgical resection followed by at least 2 years of antihelminthic therapy
  
  ⚫
**May also mimic [[hepatocellular carcinoma]], [[cirrhosis]], and [[tuberculosis]]
  +
**Causes continuously-growing tumour-like polycystic mass, made up of multiple vesicles that are lined by laminated germinal layer
  +
*Can cause cholestatic [[jaundice]], [[cholangitis]], [[portal hypertension]], and [[Budd-Chiari syndrome]]
  +
  +
== Diagnosis ==
  +
  +
* Combination of radiologic and serologic investigations
  +
*A single negative serologic test does not rule out infection
  +
* May be confirmed by biopsy
  +
  +
=== Case Definition (Alberta) ===
  +
  +
* Typical organ lesion detected by imaging with US or CT
  +
* AND histopathology compatible with alveolar echinococcosis
  +
* AND
  +
** Detection of ''E. multilocularis'' by serology
  +
** OR detection of ''E. multilocularis'' by molecular diagnostic methods
  +
  +
=== Imaging ===
  +
  +
* Ultrasound or CT demonstrates lesions which typically have an irregular contour, no well-defined wall, central necrosis, and irregular intralesional and wall calcifications
  +
  +
=== PNM Classification ===
  +
  +
* P=parasitic mass in the liver, N=neighbouring organ involvement; M=metastases
  +
  +
{| class="wikitable"
  +
!
  +
!P
  +
!N
  +
!M
  +
|-
  +
|X
  +
|Primary tumour cannot be assess
  +
|Not evaluable
  +
|Not evaluable
  +
|-
  +
|0
  +
|No detectable tumour in liver
  +
|No regional involvement
  +
|No metastasis
  +
|-
  +
|1
  +
|Peripheral lesions without proximal vascular and/or biliary involvement
  +
|Regional involvement of contiguous organs or tissues
  +
|Metastasis
  +
|-
  +
|2
  +
|Central lesions with proximal vascular and/or biliary invovlement of 1 lobe
  +
| rowspan="3" |
  +
| rowspan="3" |
  +
|-
  +
|3
  +
|Central lesions with hilar vascular or biliary involvement of both lobes and/or with involvement of 2 hepatic veins
  +
|-
  +
|4
  +
|Any liver lesion with extension along the vessels and biliary tree
  +
|}
  +
  +
== Management ==
  ⚫
*Main treatment is surgical resection followed by at least 2 years of antihelminthic therapy (e.g. [[albendazole]])
 
*Poor prognosis, with 90% 10-year mortality if untreated
  
*Poor prognosis, with 90% 10-year mortality if untreated
   

Latest revision as of 12:09, 2 March 2023


Background

Microbiology

  • Cestode in the Echinococcus family
  • Disease is caused by the larval form

Life Cycle

  • Definitive hosts are canid carnivorous animals, including urban coyotes
  • Eggs contaminate the environment, including produce
    • They are infective after a few days, and are viable for up to 16 months at 4ºC
  • Intermediate hosts (metacestode) are rodents, possibly pigs, and and incidentally humans
  • Intermediate host is eaten by the definitive host, completing the life cycle

Epidemiology

  • Estimated 18,000 cases annually
  • Worldwide in the northern hemisphere
    • Most cases in China (90%), followed by Japan and Russia
    • Rare in North America
  • Within Canada:
    • Associated with arctic foxes and wolves
    • Alberta has highest number of cases, with 19 cases from 2013 to 2021
    • 0 to 3 case reports in other provinces

Clinical Manifestations

  • Causes alveolar echinococcosis
  • Incubation period 5 to 15 years
  • Vague abdominal pain may precede diagnosis by years
  • Presents as a metastatic malignancy of unknown primary, mot commonly with malaise, weight loss, and right upper quadrant discomfort
  • Can cause cholestatic jaundice, cholangitis, portal hypertension, and Budd-Chiari syndrome

Diagnosis

  • Combination of radiologic and serologic investigations
  • A single negative serologic test does not rule out infection
  • May be confirmed by biopsy

Case Definition (Alberta)

  • Typical organ lesion detected by imaging with US or CT
  • AND histopathology compatible with alveolar echinococcosis
  • AND
    • Detection of E. multilocularis by serology
    • OR detection of E. multilocularis by molecular diagnostic methods

Imaging

  • Ultrasound or CT demonstrates lesions which typically have an irregular contour, no well-defined wall, central necrosis, and irregular intralesional and wall calcifications

PNM Classification

  • P=parasitic mass in the liver, N=neighbouring organ involvement; M=metastases
P N M
X Primary tumour cannot be assess Not evaluable Not evaluable
0 No detectable tumour in liver No regional involvement No metastasis
1 Peripheral lesions without proximal vascular and/or biliary involvement Regional involvement of contiguous organs or tissues Metastasis
2 Central lesions with proximal vascular and/or biliary invovlement of 1 lobe
3 Central lesions with hilar vascular or biliary involvement of both lobes and/or with involvement of 2 hepatic veins
4 Any liver lesion with extension along the vessels and biliary tree

Management

  • Main treatment is surgical resection followed by at least 2 years of antihelminthic therapy (e.g. albendazole)
  • Poor prognosis, with 90% 10-year mortality if untreated
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