Parasitology



Comparative development of Echinococcus multilocularis in its definitive hosts


R. C. A. THOMPSON a1, C. M. O. KAPEL a2, R. P. HOBBS a1 and P. DEPLAZES a2a3c1
a1 World Health Organisation Collaborating Centre for the Molecular Epidemiology of Parasitic Infections, School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Western Australia 6150
a2 WHO/FAO Collaborating Center for Parasitic Zoonoses, Danish Centre for Experimental Parasitology, Royal Veterinary and Agricultural University, Dyrlaegevej 100, DK 1870 Frederiksberg C, Denmark
a3 WHO Collaborating Center for Parasitic Zoonoses, Institute of Parasitology, University of Zurich, Winterthurerstrasse 266A, 8057 Zurich, Switzerland

Article author query
thompson rc   [PubMed][Google Scholar] 
kapel cm   [PubMed][Google Scholar] 
hobbs rp   [PubMed][Google Scholar] 
deplazes p   [PubMed][Google Scholar] 

Abstract

The comparative development of Echinococcus multilocularis was studied in its definitive hosts, the fox, dog, cat and raccoon dog, beyond the pre-patent period to 90 days post-infection. All host species, apart from cats were susceptible to infection and capable of supporting substantial worm burdens. Although worms in cats matured and produced thick-shelled eggs, their overall development was retarded compared to that in other species in which the parasite matured rapidly producing large populations of gravid worms. E. multilocularis matured rapidly in foxes and raccoon dogs and this was sustained in raccoon dogs but not in foxes in which maturation of worms declined during the later stages of infection, in contrast to that in both raccoon dogs and dogs. These populations were sustained for longer in raccoon dogs and dogs compared to foxes. Cats would appear to have only a minor role in the maintenance of E. multilocularis in endemic areas, and infections in cats may be of minimal public health significance. In contrast, foxes, dogs and the recently recognized definitive host the raccoon dog, are all capable of playing significant roles in the epidemiology of alveolar echinococcosis. This study also demonstrated that the developmental processes of growth, segmentation, proglottization and maturation in adult Echinococcus are independent and can be influenced by environmental factors thus confirming earlier in vitro observations.

(Received August 24 2005)
(Revised October 27 2005)
(Accepted October 29 2005)
(January 19 2006)


Key Words: Echinococcus multilocularis; adult development; dogs; raccoon dogs; foxes; cats.

Correspondence:
c1 Institute of Parasitology, University of Zurich, Winterthurerstrasse 266A, CH-8057 Zurich, Switzerland. Tel: +411 635 85 01. Fax: +411 635 89 07. E-mail: deplazesp@access.unizh.ch Internet URL: http://www.unizh.ch/paras


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