Soil contamination by Taenia solium egg DNA in rural villages in Kongwa district, Tanzania

Abstract

The presence of<i>Taenia solium</i> DNA from eggs in soils around the households in four Tanzanian villages in Kongwa district were analysed in relation to seasonal fluctuations and infection risk implications. A total of 192 pooled soil samples from five sampling points per household were examined by droplet digital Polymerase Chain Reaction (ddPCR) from 96 pig-keeping households both during the dry and rainy seasons. The pooled samples were first processed by a flotation-double sieving technique, followed by screening for worm DNA employing universal primers targeting the mitochondrial cytochrome c oxidase subunit I (<i>cox1</i>) gene of human taeniid species and some other helminths. All DNA positive samples were later confirmed by a specific ddPCR probe assay targeting the mitochondrial <i>cox1</i> gene of <i>T. solium</i>. A total of 17.2% (n = 33) samples were positive with the universal ddPCR, whereas <i>T. solium</i> DNA was confirmed by the specific ddPCR only in 3.1% (n = 3) of the surveyed households. The detection of <i>T. solium</i> DNA in this study spells out a low risk of exposure to <i>T. solium</i> eggs from contaminated household soil. Based on our results, ddPCR seems to be a promising technology for screening <i>T. solium</i> eggs in soil.