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Experimental human infection with the dog hookworm, Ancylostoma caninum

Juergen K Landmann and Paul Prociv
Med J Aust 2003; 178 (2): 69-71.

Summary

Objective: To investigate possible routes for human infection by the dog hookworm (Ancylostoma caninum).

Design, setting and participant: Relatively small numbers of infective larvae were administered orally and percutaneously to an informed healthy volunteer (J K L) under medical supervision, at intervals between May 1998 and May 1999.

Main outcome measures: Symptoms; weekly blood eosinophil counts; faecal microscopy.

Results: A marked blood eosinophilia followed a single oral exposure to 100 infective larvae, while faecal examination remained negative. Eosinophil counts then declined gradually, although a rapid, spontaneous rise several months later, at the beginning of spring, possibly indicated reactivation of dormant larvae. Blood eosinophil numbers did not rise significantly after percutaneous infection with 200 larvae. A subsequent, smaller, oral inoculum of 20 larvae provoked an eosinophil response similar to that of the first experiment.

Conclusions: Our findings suggest that, following ingestion, some infective larvae of A. caninum develop directly into adult worms in the human gut (as they do in dogs). While the percutaneous route might be the most common means of human exposure to canine hookworm larvae, leading generally to subclinical infection, oral infection may be more likely to provoke symptomatic eosinophilic enteritis.

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  • Juergen K Landmann1
  • Paul Prociv2

  • Department of Microbiology and Parasitology, The University of Queensland, St Lucia, QLD.

Correspondence: 

Acknowledgements: 

We thank Debbie Laws and Rebekah Wilson from the School of Companion Animal Science, The University of Queensland, for providing access to infected dogs. Sullivan and Nicolaides Pathologists, Brisbane performed the routine white cell counts. Vicki Whitehall, the first author's wife (fiancée at the time), is thanked for allowing experimentation and sample collection in the bathroom of her rented townhouse.

Competing interests:

None identified.

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