# Food and Drinking Water as Sources of Pathogenic Protozoans: An Update
## 3 Waterborne and Foodborne Protozoan Infections
### Parasitic Protozoans in the General Population in Different World Regions  
An indirect overview of the distribution of four intestinal protozoan parasites in tropical regions was recently delineated by the GeoSentinel network, a global, clinical-care-based surveillance and research network created by the collaboration between the US Centers for Disease Control and Prevention (CDC) and the International Society of Travel Medicine [49]. In 2517 international travelers returning with illnesses giardiasis accounted for 82.3% cases and was most frequently acquired in south Central Asia (45.8%) and Subsaharan Africa (22.6%), cryptosporidiosis was acquired for 24.7% in Subsaharan Africa and 19.5% in south Central Asia, cyclosporiasis was acquired for 31.3% in Southeast Asia and 27.3% in Central America, and cystoisosporiasis was acquired for 62.5% in Subsaharan Africa [50].  
In European countries, according to a review of approximately 1000 studies published in the five years preceding 2021, IPI prevalence was 5.9% in children aged 0-19. _B. hominis_ was most commonly detected, with a prevalence of 10.7% of positive samples, followed by _Cryptosporidium_ spp., _G. intestinalis_, _E. nana_, and _D. fragilis_. Prevalence in single studies ranged between 1.3% for _Cryptosporidium_ and 68.3% for _D. fragilis_[51].  
_E. hystolitica/dispar_ was found to be predominant in Ethiopia, Jordan, Brazil, Iraq, and Pakistan [44; 52; 53; 54; 55; 56; 57] and to be present in Argentina [58]. _G. intestinalis_ was the second-most prevalent protozoan in Spain, Argentina, Ethiopia [46; 52; 53; 57], and Pakistan [56] and the third most prevalent in Brazil [44]. Moreover, _Cryptosporidium_ spp. were detected in Ethiopia, and the species _C. parvum_ in Jordan and Iraq [53; 54; 55]. _B. hominis_ was the most prevalent intestinal protozoan in Spain and Argentina and the second most prevalent in Jordan [46; 54; 58]. _E. nana_ and _P. hominis_ were detected in Brazil and Pakistan, respectively [44; 56]. In Brazil, _G. intestinalis_ showed a higher prevalence in children aged 0-10 years and teenagers. The decreased infection rate with increasing age was attributed to acquired immunity and improvement of personal hygiene [44]. Additionally, in Pakistan, parasitic infections were more prevalent in children, possibly as a result of poorer hygiene [56]. Multiple infections with two (3.5%) or three parasites (0.1%) comprising _B. hominis_, _G. intestinalis_, and _Cryptosporidium_ spp. were observed among schoolchildren in Spain by using PCR tests [46].  
Source of drinking water, eating raw vegetables, and hygiene-related factors such as unavailability of toilets, handwashing habits, and fingernail trimming were positively associated with IPIs [52; 53; 55; 56]. Washing vegetables was a protective factor for _B. hominis_ infection [46].  
The concern of under-reporting protozoan infections was demonstrated by a prospective study on the prevalence of cryptosporidiosis and giardiasis in children from January toFebruary 2021 in Latvia. Notably, it was found that prevalence in one month equalized the one officially reported annually in the years 2000-2020 by the National Centre for Disease Prevention and Control [59].