A novel method for the isolation of gastro-intestinal nematode eggs that allows automated analysis of digital images of egg preparations and high throughput screening.

A simple and robust method for the isolation of gastro-intestinal nematode eggs from faeces is described that uses both salt- and sugar solutions for flotation. Application of this 'salt-sugar' isolation method to large numbers of faecal samples of adult dairy cows indicates a 3- or 4-fold reduction in the proportion of e.p.g.-negative cows relative to studies that used other techniques for egg isolation. The procedure detects more eggs than the Wisconsin flotation method in replicate samples and in spiked egg-free faeces. The number of recovered eggs in spiked faecal samples is linear over a range of egg concentrations, and the transparent faecal preparations that result from the protocol can be stored as digital images which can be used as input for an efficient automated egg-counting procedure. The increased rate of processing of faeces combined with the large reduction of the percentage of e.p.g.-negative cows allows more accurate analysis of large numbers of adult or resistant animals for studies of nematode parasitism.