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Survival and development of Ascaris suum and Trichuris suis eggs in deep-litter on an organic pig farm

Roepstorff, Allan; Mejer, Helena; Nejsum, Peter and Thamsborg, Stig Milan (2011) Survival and development of Ascaris suum and Trichuris suis eggs in deep-litter on an organic pig farm. In: Proceedings of the 23rd International Conference of the World Association for the Advancement of Veterinary Parasitology, p. 107.

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Summary

Helminths in pigs have generally received little attention from veterinary parasitologists, despite Ascaris suum, Trichuris suis, and Oesophagostomum sp. being common worldwide. The present paper presents challenges and current research highlights connected with these parasites.
In Danish swine herds, new indoor production systems may favour helminth transmission and growing knowledge on pasture survival and infectivity of A. suum and T. suis eggs indicates that they may constitute a serious threat to outdoor pig production. Furthermore, it is now evident that A. suum is zoonotic and the same may be true for T. suis. With these ‘new’ challenges and the economic impact of the infections, further research is warranted. Better understanding of host-parasite relationships and A. suum and T. suis egg ecology may also improve the understanding and control of human A. lumbricoides and T. trichiura infections.
The population dynamics of the three parasites are well documented and may be used to study phenomena, such as predisposition and worm aggregation. Furthermore, better methods to recover larvae have provided tools for quantifying parasite transmission. Thus, an on-going study using helminth naïve tracer pigs has surprisingly demonstrated that soil infectivity with A. suum and T. suis increases during the first 2-3 years after pasture contamination.
Though all three helminth species stimulate the Th2 arm of the immune system, Oesophagostomum seems weakly immunogenic, perhaps via specific modulation of the host immune system. Ascaris suum and T. suis potently modulate the host immune response, up-regulating Th2 and down-regulating Th1. As a consequence, A. suum may compromise the efficacy of certain bacterial vaccines, whereas T. suis, which establish only short-term in humans, is a favourite candidate for down-regulating autoimmune Th1-related diseases in man.
Some basic research findings have offered new possibilities for future sustainable control measures. For example, the heredity of host resistance to A. suum is so high that breeding for resistant pigs may be a possibility. Experimental studies have demonstrated that fermentable dietary carbohydrates have an antagonistic effect on Oesophagostomum and to a lesser extent on T. suis and A. suum, whereas egg-destroying microfungi may be used to inactivate the hard-shelled A. suum and T. suis eggs in the environment.
Helminth control in Denmark has previously relied solely on anthelmintic treatment in herds with low helminth transmission. When indoor transmission rates increase, or in outdoor herds with high pasture contamination levels, medication may advantageously be combined with sustainable control measures, such as selected pig genomes, bioactive forages, and egg-destroying microfungi.


EPrint Type:Conference paper, poster, etc.
Type of presentation:Keynote presentation
Subjects: Animal husbandry > Production systems
Animal husbandry > Health and welfare
Animal husbandry > Production systems > Pigs
Research affiliation: Denmark > Organic RDD > PAROL
Denmark > ICROFS - International Centre for Research in Organic Food Systems
Denmark > KU-LIFE - Faculty of Life Sciences
Deposited By: Mejer, Dr Helena
ID Code:20238
Deposited On:04 Jan 2012 12:26
Last Modified:04 Jan 2012 12:26
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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