Differentiation of two Oesophagostomum spp. from pigs, O. dentatum and O. quadrispinulatum, by computer-assisted image analysis of fourth-stage larvae.

A method was developed to differentiate between fourth-stage larvae (L4) of two species of porcine nodular worms, Oesophagostomum dentatum and O. quadrispinulatum, by computer-assisted analysis of digitised microphotographs of L4 grown in vitro for various time periods and of L4 ex vivo. The overall lengths of the larvae and the lengths of the oesophagus as well as parameters describing the shape of the oesophagus and buccal capsule were measured and a formula based on these parameters was developed that could differentiate between the two species on the basis of the morphometric data. It was demonstrated that morphometry can produce unbiased data which can be employed for the calculation of indices suitable for the differentiation of morphologically different specimens. Computer-based techniques facilitate the processing of the complex data and offer the option for automation of measurements for routine applications.