Ancylostoma caninum: Adult worm removal,corticosteroid treatment,and resumed development of arrested larvae in dogs |
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Authors: | Gerhard A Schad Michael R Page |
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Institution: | Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, U.S.A. |
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Abstract: | Beagles, 2 months old and helminth naive, were infected with chilled arrest-prone larvae of Ancylostoma caninum. Eighteen days after infection, the pups were treated with an adulticidal anthelmintic (disophenol or dichlorvos) to remove adult worms while allowing dormant larvae to survive. Examinations of treated pups at necropsy demonstrated that the remaining hypobiotic larvae could develop and mature in the same dogs within which their development was arrested. Removal of adult worms was not a stimulus for resumption of larval development. Indeed, larvae resumed development in untreated control dogs harboring substantial populations of adult worms. Prednisolone treatment of dogs, although apparently producing some degree of immunodepression as judged by lymphocyte transformation assays, did not release larvae from dormancy. In fact, the dogs treated with the corticosteroid harbored significantly greater populations of hypobiotic larvae at 100 days after infection than did their untreated controls. Some hypobiotic larvae appeared to resume development spontaneously and idiosyncratically during the 2 to 3 month duration of these experiments. Whether a synchronous resumption of development would occur given other stimuli or spontaneously after a longer period of dormancy remains to be determined. |
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Keywords: | Hookworm Nematode parasitic larvae hypobiotic Arrest Development Dog Disophenol Dichlorvos Corticosteroids Prednisolone |
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