# Food and Drinking Water as Sources of Pathogenic Protozoans: An Update
## 4 _Cryptosporidium_ spp.
### Cryptosporidium _spp. in Drinking Water_  
Control of _Cryptosporidium_ is a major challenge for drinking water sanitization sinceocysts can pass through different types of filters. Though the conventional filtration methods using coagulation, flocculation, and sedimentation could remove 99% of _Cryptosporidium_ cells [10], ubiquitous presence, resistance to disinfectants, and lack of retention of the filtration stage [4] have led to large waterborne outbreaks [4; 9; 10; 122; 123]. Indeed, _Cryptosporidium_ oocysts can survive for more than seven days at concentrations higher than 1 ppm of free available chlorine, the recommended concentration for sanitization of drinking water [10]. Moreover, _Cryptosporidium_ spp. was found to be able, under defined conditions, to aggregate and reproduce in biofilms formed in domestic water networks so that oocyst could be retained and gradually released [5]. The prevalence of _Cryptosporidium_ spp. was higher among people with no access to household water or dependent on river water in Qatar [97] and in people using desalinated potable water transported with tanker trucks and stored in overhead tanks in Kuwait [115]. In Gamba consumption of stored drinking water was associated with an increased risk of cryptosporidiosis in children below five years of age [114] and diarrhea caused by _Cryptosporidium_ in children younger than two years was associated with public tap water use in southwest Ethiopia [117]. In the years 2010-2020, drinking water was the origin of 7% of waterborne outbreaks caused worldwide by _C. hominis_, with genotype IbA10G2 most frequently involved [113]. In the USA, drinking-water-related cryptosporidiosis outbreaks accounted for 28% of cases between 2013 and 2014, and it was estimated that 748,000 cases occur annually, of which only 2% are officially reported [89]. In France, from 2017 until 2019, 60% of notified cases of cryptosporidiosis were associated with unbottled water consumption [90], and in an outbreak involving military trainees in southwest France, _C. hominis_ IbA10G2 was detected in the water network. The contamination was eliminated by restricting the polluting activities and installing an additional ultrafiltration module in the water treatment plant [9; 123]. The largest waterborne outbreak described in France, with several thousand cases, occurred in the Provence-Alpes-Cote d'Azur region from October to December 2019 and was caused by leaching after intense precipitation. Water sources were contaminated by multiple _C. parvum_ subtypes (IIdA22G1, IIa15G2R1, IIdA17G2, IIdA18G1, IIa17G1R1). The high number of waterborne cryptosporidiosis outbreaks in France can be explained by leaching from livestock farms; the ineffectiveness of drinking water treatment plants, mainly based on sedimentation and chlorination; and the prevalent use of tap water for human consumption. Nevertheless, _Cryptosporidium_ spp. are not yet included among the microbiological criteria for drinking water in the country [9]. In Italy, drinking water contaminated by _C. parvum_ subtype IIdA25G1 caused an outbreak of cryptosporidiosis among tourists staying in a small town in the Apennines. Since water disinfection measures adopted in the area may be insufficient to inactivate these parasites, the authors warned that testing drinking water for protozoan pathogens, which is not commonly included in routine water analysis in Italy, should be implemented [122]. In contrast, in China, _Cryptosporidium_ was listed as one of the microbial contaminant indicators in Chinese Standards for Drinking Water Quality since 2006, though no water borne outbreaks were reported in the country. A retrospective epidemiological analysis showed that _Cryptosporidium_ prevalence was significantly associated with the use of well water and with drinking unboiled water [124]. The first global comprehensive scoping review on the presence of _Cryptosporidium_ spp. in drinking water regarded groundwater sources and included literature records from the year 1992 to July 2019 [5].