Comparison of fecal analysis methods for the detection of Platynosomum fastosum in naturally infected cats.

OBJECTIVES

Diagnosis of Platynosomum fastosum Kossack 1910, a liver fluke of cats, can be challenging, with infections potentially not identified depending on the fecal analysis method used. The aim of this study was to compare three methods for identification of P fastosum eggs in feces.

METHODS

Feces from 50 cats with unknown infection status from a location endemic for P fastosum were analyzed. The methods used included double centrifugation with Sheather's sugar flotation solution (specific gravity 1.28); the Mini-Parasep (Apacor) flotation kit with ZnSO4 (specific gravity 1.20); and the Mini-Parasep sedimentation kit with Triton X/ethyl acetate solution.

RESULTS

Thirty-four cats were identified as positive for P fastosum. Of these cats, 33 were identified with the double centrifugation method, 16 with the Mini-Parasep flotation kit and 11 with the Mini-Parasep sedimentation kit. Using the total number of samples identified as positive by at least one method as the true positive, the sensitivity of the methods was 97.1% for double centrifugation, 47.1% for the Mini-Parasep flotation kit and 32.4% for the Mini-Parasep sedimentation kit. Other parasite eggs (eg, Ancylostoma tubaeforme, Trichuris species and Toxocara cati) also were detected more frequently with the double centrifugation method.

CONCLUSIONS AND RELEVANCE: Of the three methods tested, double centrifugation with Sheather's sugar flotation solution was the most effective in identifying cats with P fastosum and other helminth eggs in their feces. The lower specific gravity of the flotation solution in the Mini-Parasep flotation kit likely influenced the results. A primary drawback of the Mini-Parasep sedimentation kit was the amount of sediment. While more sediment was examined than recommended in the manufacturer's instructions, this was still only a small portion of the total sediment. In addition, reading the slides took longer than with the other methods.