FLOTAC: an improved method for diagnosis of lungworm infections in sheep

Abstract

The FLOTAC techniques involve the spinning of faecal samples onto the surface of counting chambers to permit enumeration of parasitic elements (eggs, larvae, oocysts and cysts) to an accuracy of one parasitic element per gram of faeces. In the present study it is demonstrated that FLOTAC provides a rapid and very sensitive method for counting of lungworm larvae of sheep. The optimum flotation solution for lungworm larvae is zinc sulphate and mercury II iodide (s.g. 1.45) although zinc sulphate (s.g. 1.20 or 1.35) on its own also gave good results. Samples preserved in 5% formalin gave the highest counts but fresh, frozen and samples in 10% formalin also gave higher counts than McMaster and simple flotation. Larval counts of 307 field samples gave up to 1.27x more positives samples than use of Baermann funnels and up to 4.18x more larvae per sample. As FLOTAC is faster than Baermannisation of samples it offers a better method of counting larvae in ruminant faecal samples.