Probability of correctly identifying a lice-affected flock of sheep using visual inspection (fleece parting)

Nearly two-thirds of Queensland, Australia, sheep graziers who detect lice (Bovicola ovis) in their flocks do so by fleece parting or visual inspection of the skin for lice. However, visual inspection is known to have low sensitivity which varies with the number of lice per infested sheep. This report examines the effectiveness of fleece parting in lice detection under varying levels of infestation, test sensitivity and sample size. The authors conclude that fleece parting should be considered as just one source of information to be taken into consideration by graziers when determining the probable lice status of a flock.