PARASITES AND PARASITIC DISEASES OF DOMESTIC ANIMALS

Ascaris suum

Introduction

A. suum is one of the commonest nematodes of pigs and is also the largest with female worms ranging from 25 to 40 cm in length and 5 mm in diameter. Males are smaller, ranging from 15 to 25 cm long and 3 mm in diameter. The image shows mature Ascaris suum from a pig at necropsy. The small intestine is opened to show the mass of adult worms present.

The mouth opening is surrounded by three lips as shown in this scanning electron micrograph. There is one dorsal lip (A) and two ventro-lateral lips (B) The yellow arrows point to rows of tiny denticles on the inner surface of each lip.