Mini-FLOTAC for counting Toxoplasma gondii oocysts from cat feces – Comparison with cell counting plates

Abstract

Oocysts of Toxoplasma gondii represent one of the most common environmental contaminants causing the zoonotic infection toxoplasmosis. The aim of the present study was to compare the Mini-FLOTAC device with traditional cell counting plates (Kova Slide) for the detection of T. gondii oocysts from feline feces. Two types of experiments were performed: (i) purified oocysts were counted in different dilutions and (ii) specific pathogen free T. gondii-negative cat feces was inoculated with numbers of purified oocysts and counting was performed directly from feces. Our analysis showed a thousand times higher sensitivity of Mini-FLOTAC (5 × 102 oocysts) compared to Kova Slide (5 × 105 oocysts). Also, when compared by McNemar's test, counting of the purified oocysts showed a higher sensitivity of Mini-FLOTAC compared to Kova Slide, for a dilution of 103 oocysts/ml (chi2 = 6.1; P < 0.05). A better sensitivity was also found with Mini-FLOTAC in dilutions of 105 and 104 oocysts/ml, when counted from feces (chi2 = 4.2 and 8.1, respectively, P < 0.05). Our results show that Mini-FLOTAC is more sensitive than traditional methods of T. gondii oocysts detection and quantification is more accurate. Furthermore, Mini-FLOTAC simplicity and cost effectiveness allow it to be used with light microscopes in any laboratory or field conditions. We therefore recommend its use for regular screening. Further studies are needed to validate Mini-FLOTAC for the detection of oocysts in soil and water samples in field conditions.