Epidemiology
Reporting Obligations
Echinococcus multilocularis infection is designated as a disease of public health significance and is reportable under the Ontario Health Protection and Promotion Act. Report suspect and confirmed cases within one business day to the local Health Unit.
Aetiologic Agent
Echinococcus multilocularis infection in humans is caused by the ingestion
of eggs of the E. multilocularis tapeworm. Once ingested, the eggs develop
into the larval form, which grows as multiple, small budding cysts.
Clinical Presentation
Proliferation of the larval stage of E. multilocularis produces a highly
invasive, destructive disease called alveolar echinococcosis. Once clinical
signs of alveolar echinococcosis develop, lesions are usually found in the
liver and expand to produce solid, tumour-like masses. Metastases can
result in secondary cysts and larval growth in other organs. Clinical
manifestations depend on the size and location of cysts, but are often
confused with hepatic carcinoma and cirrhosis.Modes of Transmission
Ingestion of eggs passed in the feces of foxes, coyotes, dogs or cats that
have fed on infected rodents. Fecally soiled dog hair and other
environmental fomites also serve as vehicles of infection.
- Incubation Period
Infection of humans with E. multilocularis is characterized by an initial
asymptomatic incubation period of 5–15 years.
Period of Communicability
E. multilocularis eggs are highly resistant, and may remain infective for
approximately one year in a suitable, moist environment at lower
temperatures. There is no person to person transmission.
Risk Factors/Susceptibility
Susceptibility is general. Due to the long incubation period, alveolar
echinococcosis usually affects adults.
Diagnosis & Laboratory Testing
Diagnosis is complex and based on serodiagnosis for early stages of
infection, and histopathology for later stages of infection, when lesions
have become apparent in the liver or other organs.
Serologic testing for E. multilocularis is not performed in Canada. Rather,
serum specimens with a requisition for “alveolar hydatid” or “E.
multilocularis” are sent for reference laboratory testing in Switzerland,
after approval of the request by the Public Health Ontario (PHO)
Laboratory.
Treatment & Case Management
Treatment is under the direction of the attending health care provider. All
patients require treatment.
With treatment the prognosis of this disease has improved significantly.
Early diagnosis and treatment with albendazole improves life expectancy
significantly.
DRUG SUSCEPTIBILITY: Sensitive to mebendazole, albendazole, praziquantel
https://www.canada.ca/en/public-health/services/laboratory-biosafety-biosecurity/pathogen-safety-data-sheets-risk-assessment/echinococcus-multilocularis.html
Provide cases with information about the infection and how it is
transmitted as listed below.
Education of both pet owners and individuals in high risk occupations
(veterinary staff, wildlife workers, hunters and trappers, etc.) about the
lifecycle of the parasite and risks of exposure to E. multilocularis eggs
is an important preventive measure.
Hunters and trappers handling foxes, coyotes or other wild canids should
wear plastic gloves when handling these animals or their carcasses.
Wild fruits and vegetables should not be collected from the ground or
eaten. All wild-picked foods should be washed carefully or cooked before
being eaten.
All dogs and cats having access to wild rodents in areas known to be
endemic for E. multilocularis should be dewormed monthly with praziquantel
to reduce the risk of exposure to parasite eggs in household environments.
Pet owners should prevent dogs and cats from eating rodents.
Regular, frequent hand hygiene after handling pets and their feces, and
before handling food, can reduce the risk of transmission to humans. Areas
inhabited by dogs and cats with known E. multilocularis infections should
be decontaminated to prevent risk of exposure to parasitic eggs on surfaces
such as pet beds, floors, carpets and car interiors.
Patient Information
Additional Resources
Centers for Disease Control and Prevention. “Echinococcus”, December
2012.
Public Health Ontario. “Management of Echinococcus multilocularis Infections in Animals Guideline, 2018”
References
Ministry of Health, Infectious Diseases Protocol - Ontario Public Health Standards, 2022.