Echinococcus multilocularis

Background

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

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

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
- 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 jaundrice, cholangitis, portal hypertension, and Budd-Chiari syndrome

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

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