Pathogenesis of Liver Lesions in Mice following a Primary Infection with Ascaris suum

Abstract. The development of liver lesions in mice infected with Ascaris mum is described and compared to the lesions in pigs. The findings suggest that liver necroses in mice are initially periacinar (centrilobular), caused by anoxia resulting from a vascular obstruction by the A. suum larvae located in the sinusoids; and that the lesions in pigs following a primary infection have a different pathogenesis. It is concluded that mice are unsuitable models for studying the pathogenesis of A. suum-induced liver lesions in pigs. The common occurrence of the large intestinal nematode Ascaris mum in pigs and the great medical and economic problems involved have promoted intensive research in porcine ascariasis for decades. The main lesion seems to be the liver damage (“milk spots”) caused by the migrating larvae in infected pigs. Larval A. mum infections can be established easily in laboratory animals such as rats, guinea pigs and mice, and for years these animals have served as models for an understanding of larval ascariasis in pigs, particularly the immunological aspects. The suitability of small laboratory animals as models for ascariasis in pigs never has been questioned; on the contrary, it was concluded after studies on the developmen