Studies on ascariasis in pigs. The seasonal incidence and the effects of infection on growth, with special attention to factors of resistance to harmful infection.

Statistics published by the Dominion Department of Agriculture of Canada show that about 20% of the Canadian pig crop dies every year. This mortality is due to several causes -- bacterial, virus, parasitic, nutritional diseases and bad management. Diseases due to virus and bacterial infections are comparatively few and the means for their control are not lacking. However, there are disease problems of a more complex nature; these include parasitic as well as nutritional diseases. This has been previously pointed out by Watson. It is widely believed that intestinal parasites play an important role in diseases of swine. The intestinal parasite most commonly found in pigs in Canada is Ascaris lumbricoides Linn. 1758. This nematode is readily recognized by breeders and is generally believed to be an important factor in swine losses. It is this nematode that has claimed the attention of most investigators interested in the problem of swine diseases and losses. However, while a large amount of work has been carried out with regard to the exact relationship between Ascaris infection and its clinical and pathological manifestations in the host animal, this relationship is still very poorly understood