Waterborne Giardia and Cryptosporidium: contamination of human drinking water by sewage and cattle feces

Abstract

Water is an important vehicle for pathogens such as Cryptosporidium spp. and Giardia duodenalis. In fact, these organisms are responsible for almost 58% and 38% of the waterborne outbreaks reported in ~60 years. Characteristics related to the environmental phase of these protozoa and the different types of hosts are important factors related to environmental contamination. In cryptosporidiosis and giardiasis, outbreaks caused by waterborne pathogens are identified as major risk factors for contamination of water resources by untreated sewage and the entrainment of cattle feces in rainwater. Further, this review covers taxonomic, biologic, and epidemiologic aspects such as prevalence, risk factors, and molecular characterization of these protozoa observed in humans and cattle in order to elucidate the role of these hosts in environmental pollution, and consequently, as a source of infection for susceptible humans, especially in rural areas. Alternative water resources such as wells and springs are used without water treatment and potability monitoring. Epidemiological data are useful, but insufficient to characterize the source of infection, thereby requiring the use of appropriate molecular methods for subtyping the protozoa detected in environmental and feces samples as well as for assessing public health risk.