[Coprological diagnosis: what's new?].

Analysis of faecal samples for the presence of parasite eggs, larvae, cysts and oocysts is the most widely used diagnostic procedure both in veterinary and human parasitology. After its fundation by C. J. Davaine in 1857, several copromicroscopic techniques have been developed. The McMaster technique developed and improved at the McMaster laboratory of the University of Sidney (whose name derives from one of the great benefactors in veterinary research in Australia, the McMaster family) is the most universally used technique for estimating the number of parasite elements in faeces. In the literature, however, many variations of the McMaster technique are to be found, and there is a clear need for the standardization of this technique. Recently, we have conducted a study in order to evaluate the influence of flotation solution, sample dilution, and the choice of McMaster slide area (volume) on the reliability of the McMaster technique in estimating the egg counts of gastrointestinal strongyles and Dicrocoelium dendriticum in a composite sample of faeces from naturally infected sheep. The study used 14 flotation solutions (having specific gravities between 1.200 and 1.450), 6 sample dilutions (1:10, 1:15, 1:20, 1:30, 1:40 and 1:50), and 4 McMaster slide areas (volumes) (McM 0.15 ml, McM 0.3 ml, McM 0.5 ml and McM 1.0 ml). The type of flotation solution used significantly influenced the EPG in the GI strongyle and in the D. dendriticum egg counts. All the sucrose based solutions at s.g. between 1.200 and 1.350 floated more GI strongyle eggs than the others. With respect to D. dendriticum, only six solutions were capable of floating eggs and the potassium jodomercurate solution (s.g.1.440) floated more eggs than the others. The reliability of the McMaster technique regarding sample dilution was high for both GI strongyle and D. dendriticum EPG at 1:10 and 1:15, and then progressively decreased with increasing dilution. The reliability of the McMaster technique regarding the choice of the McMaster slide area (volume) was high for both GI strongyle and D. dendriticum EPG at the McMaster slide area (volume) of 1.0 ml, i.e., the total area of the McMaster slide. The EPG counts resulting from choosing any of the other three McMaster slide areas (volumes), i.e. McM 0.15 ml, McM 0.3 ml, or McM 0.5 ml, produced unreliable over-estimates. In order to improve the sensitivity of copromicroscopic diagnosis, at our laboratory a novel technique (flotation-translation) was established based upon a new apparatus, the FLOTAC. This technique allows, after the centrifugation, the real count of the parasite elements in 1 gram of feaces.