Public Health Implication of Drinking Water Sources Contaminated with Giardia spp. and Cryptosporidium spp. in South Ethiopia

Abstract Background: Giardia duodenalis and Cryptosporidium spp. are topmost causes of gastrointestinal diseases mainly in socio-economically disadvantaged regions. Understanding the molecular diversity and distribution of these parasites in water sources and the environmental variables that influence their prevalence is important to effectively control infections in at-risk populations, however, the state of knowledge about risks of these parasites associated with source water is little in Africa. This study aimed at characterizing risks of Giardia duodenalis and Cryptosporidium spp. from water sources in southern Ethiopia.Methods: Twenty-one water samples (10L per source) were collected from five different types of drinking water sources. Sample was analyzed using immunofluorescence assay with fluorescein isothiocyanate–monoclonal antibodies and nested PCR; tpi-PCR was used for genotyping purpose in Giardia duodenalis isolates and SSU-rRNA and gp60-PCR in Cryptosporidium spp. isolates. Statistical analysis was performed using Spearman’s rho correlation and independent-samples nonparametric test.The risk was characterized using quantitative microbial risk assessment.Results: The immunofluorescence assay showed that cyst was detected in 81% (17/21) and oocyst in 71% (15/21) of the samples with mean concentrations of 64.6 cysts.10 L-1 and 62.8 oocysts.10 L-1. Genotypic analysis showed that Giardia duodenalis assemblage B was genotyped in 29.4% (5/17), assemblage A in 17.6% (3/17) and assemblages A+B in 52.9% (9/17) of the samples. Cryptosporidium spp. genotype was detected in 57.1% (12/21) of the samples; Cryptosporidium parvum in 38.1% (8/21), Cryptosporidium hominis in 14.3% (3/21) and Cryptosporidium parvum and Cryptosporidium hominis in 4.7% (1/21) of the samples. The average probability of illness from the water sources was 0.06 for Giardia duodenalis and 0.22 for Cryptosporidium spp.Conclusions: The finding highlights the significance of water for transmission of Giardia spp. and Cryptosporidium spp. in southern Ethiopia. Genotypes detected in the samples indicate multiple sources likely contaminated the sources. Health risk that is inferred from the water sources to the public are significantly higher than most other reported findings. This study recommends the need of regular follow-up, improvement in water treatment facilities and setting appropriate legislation in areas where cycles of parasitic infection is linked to water sources.