Flow-cytometry analysis of sheep-nematode egg populations

Flow cytometry was applied to the analysis of nematode populations. Three strains of Haemonchus contortus susceptible or resistant to anthelmintics were studied. Eggs were chosen for these analyses. Data on light-scatter emissions and native green fluorescence were collected. In addition, the size of the eggs (image analysis), the hatching rate, and the susceptibility to benzimidazoles were measured. The results showed that nematode eggs are a suitable material for multiparametric flow-cytometry analyses. Forward-scatter emission is a discriminating parameter for the egg size. The hatching rate and side-scatter emission have a significantly positive relationship. For resistant strains, the rate of resistance shows a significant regression on the native greenfluorescence pulses that might reflect the state of oxidation of associated flavin molecules.