A simple method to count total faecal Capillaria worm eggs in racing pigeons (Columba livia)

Capillaria columbae and C. longicollis are fine threadworms found in racing pigeons' small intestines that produce a characteristic lemon shaped bipolar egg. Clinically, capillariasis in racing pigeons can present as severe illness and it has been suggested that worms may affect race performance. A major aim of this study was to validate a cheap, simple to perform flotation technique for counting Capillaria worm eggs in racing pigeon droppings. Trials using reference samples of pigeon droppings laced with 348, 275 and 129 Capillaria eggs per gram, found a typical flotation method based on the modified Wisconsin technique to be inaccurate at counting worm eggs. The main sources of error were due to the loss of eggs in the faecal discard and insufficient flotation time. A new technique, using 0.15 g sample size and 8h flotation time resulted in significantly improved test accuracy. On average the new technique recovered 93% of eggs from reference samples with 129-348 epg concentration, recovering 197 times more eggs than the modified Wisconsin technique. Typical percentage error, as a measure of absolute reliablility, was 10% for the new technique and 50% for the modified Wisconsin technique. The regression line on a test-retest series of samples over a range of egg counts from 0 to 573 epg had a gradient of 0.96 (y=0.96x+6.28; r(2)=0.8408) for the new technique and 0.54 (y=0.54x+0.06; r(2)=0.4249) for the modified Wisconsin technique. The Pearson product moment correlations of the new technique and the modified Wisconsin technique were 0.92 and 0.65 respectively. As measures of relative reliability both the gradient of the regression line and the Pearson product moment correlation further suggested better repeatability of the new technique. It was concluded that the new technique would be an appropriate quantitative method of assessing worm egg burdens in racing pigeons.