Canis ISSN: 2398-2942

Echinococcus multilocularis

Synonym(s): E. multilocularis

Contributor(s): Dwight Bowman, Maggie Fisher

Introduction

Classification

Taxonomy

  • Class: Cestodae.
  • Family: Taeniidae.
  • Genus: Echinococcus.

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Clinical Effects

Epidemiology

Habitat

  • Adult tapeworms in anterior small intestine of fox, occasionally dog and rarely cat Echinococcus granulosus adult embedded within intestinal villi.
  • Eggs in environment: feces, soil, on pelts, on low level blackberries, etc.
  • Metacestodes (alveolar cysts) in rodents, particularly voles.
  • In human, alveolar cysts are found almost exclusively in the liver, although metastatic and local spread to other organs can then occur.

Lifecycle

  • 1. Adult.
  • 2. Egg.
  • 3. Alveolar cyst containing protoscolices.

Transmission

Transmission to vole
  • Ingestion of eggs in fox feces.
Transmission to fox/dog
  • Ingestion of protoscolices in fertile alveolar cyst in vole.
  • Foxes may eat 1000 or more voles a year.

Pathological effects

  • Very little or no protective immunity develops within the dog population.
  • It is not known if immunity develops in the sylvatic intermediate host population.

In dog definitive host

  • Adult worms, even in large numbers, in fox/dog cause little pathology and essentially no clinical signs are apparent.

In humans

  • The alveolar cyst is multivesicular and invasive, growing by adding vesicles and invading the liver parenchyma.
  • The early presenting sign is liver pain followed by jaundice, by which time metastasis to other organs may have occurred. The infection is fatal if untreated and treatment is difficult.

Control

Control via animal

  • Anthelmintic treatment of dog.

Control via chemotherapies

Control via environment

  • Egg resistant to many disinfectants.
  • Desiccation or dry heat kills eggs.
  • Sodium hypochlorite solution (3.75% or higher) for at least 2-3 hours can be used to clean concrete surfaces.

Other countermeasures

Control programs
  • Currently, every dog and cat entering the UK under the PETs Scheme Pet Travel Scheme is treated with praziquantel to eliminate Echinococcus spp tapeworms (http://www.defra.gov.uk/animalh/quarantine/index.htm).
  • In the endemic area it is recommended that dogs that may have access to rodents are treated at monthly intervals. Epidemiologically, cats are far less important than dogs as a source of infection and so treatment of cats may be recommended if the cat has access to rodents and the owner is concerned to prevent risk. The treatment on re-entry to the UK is insufficient to prevent patent infection if the animal has been in the endemic area for more than a month. Where an owner is planning to take a dog or cat to the area where E.multilocularis is endemic then monthly treatment should be recommeded where the pet may have access to rodents.
  • Some success had been achieved in controlling infection in foxes using praziquantel-treated bait in the Zurich area.

Diagnosis

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Eckert J & Deplazes P (2004) Biological, epidemiological, and clinical aspects of echinococcosis, a zoonosis of increasing concern. Clinical Microbiology Reviews 17, 107-135.
  • Roberts M G & Aubert M F A (1995) A model for the control of Echinococcus multilocularis in France. Vet Parasitol 56, 67-74 (Mathematical model of control in foxes).

Other sources of information

  • Eckert J et al (2002) WHO/OIE Manual on echinoccosis in humans and animals: a public health problem of global concern. Published by WHO and OIE, Paris.
  • www.esccap.org: website for European Scientific Counsel: Companion Animal Parasites, guidelines for worm control in cats and dogs.
  • Eckert J (1998) Alveolar echinococcosis (echinococcus multilocularis) and other forms of echinococcosis (echinococcus vogeli and echinococcus oligarthrus. In: Zoonoses. Biology, clinical practice and public health control. Oxford University Press. pp 689-716.

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