Preliminary insights regarding water as a transmission vehicle for Cryptosporidium and Giardia in Tigray, Ethiopia

This study was part of a larger One Health project with the aim of investigating the epidemiology of Cryptosporidium and Giardia infections among humans and animals in rural areas of Tigray, Ethiopia. Here we report on the contamination of different drinking water sources in four locations of this region with these Cryptosporidium oocysts and Giardia cysts; 19 samples were from unprotected surface water sources and 18 from protected water sources. A modified version of the standard ISO 15553 technique was used for analysis, and Giardia cysts were detected in 6 of the samples (16%) and Cryptosporidium in two (5%), with one of these samples containing both parasites. The number of Giardia cysts in positive samples ranged from 3 to 22 cysts per 10 L sample, and the number of Cryptosporidium oocysts in positive samples ranged from 1 to 3 oocysts per 10 L sample. Low numbers of parasites and absence of nuclei, as indicated by the absence of DAPI staining, precluded further molecular analyses. We found no association with contamination and whether the water source was protected or not, but there was an association with location, with one location more likely to have a contaminated sample than the others. These preliminary data suggest that this location should be in focus for further parts of this study.