# Food and Drinking Water as Sources of Pathogenic Protozoans: An Update
## 18 Discussion  
This review summarizes recent records on the transmission of protozoan infections from food and drinking water, with the number of published outbreaks and cases reflecting the relevance of the pathogen for public health, albeit representing a small fraction of the actual number of infections occurring. The number of cases and outbreaks of waterborne and foodborne protozoan infections published for each pathogen since 2019 are shown in Figure 2.  
In Figure 2, 271 cases reported since 2019 for _Cryptosporidium_ spp. [127; 132; 90] are not shown because they were too numerous to be presented in the graph. Moreover, it was not clear if they were from outbreaks. The low number of cases and outbreaks reported for _G. intestinalis_ and _B. coli_ reflects the rarity of severe infections caused by these microorganisms that are, for this reason, poorly investigated. Nevertheless, the long-term detrimental effects on the well-being of _G. intestinalis_[23; 29; 30; 31] and the possible severe infections caused by _B. coli_[280; 281] justify further studies on their occurrence in the general population, associations with chronic pathologies, and sources of contamination. All cases reported for _E. histolytica_ and _C. belli_ were included despite the lack of information on the causative dietary source since the acquisition from food and water is the most probable for these infectious agents [7; 269]. It can be observed that _B. hominis_, _B. coli_, _E. histolytica_, and _C. belli_ were identified in sporadic cases rather than outbreaks. The lack of reports for _D. fragilis_ and _P. hominis_ reflects the poorly defined pathogenicity of these species so further investigation into the occurrence of symptomatic cases after the consumption of contaminated food or water should be considered [21, 284, 286]. The identified or most probable sources of infection associated with recent cases and outbreaks of waterborne and foodborne protozoan infections are shown in Table 1. \begin{table}
\begin{tabular}{c c} \hline
**Infectious Agent** & **Dietary Infection Sources in Cases and Outbreaks \({}^{*}\)** \\ \hline _Cryptosporidium_ spp. & Drinking water, unpasteurized or re-contaminated pasteurized milk, meat, dairy foods, dishes prepared outdoors, barbecued foods, raw foods, raw vegetables, raw fruits, \\  & unpasteurized drinks, apple juice, raw shellfish [9, 89, 97, 100, 113, 114, 121, 122, 123, 124, 127, 128, 129, 131, 133] \\ \hline _Entamoeba_ spp. & Drinking water, alcoholic fermented sap of the Palmyra toddy [7, 209] \\ \hline _Toxoplasma gondii_ & Raw vegetables, fruits, raw or undercooked meats, unpasteurized milk, raw cow’s milk \\  & cheese, raw or undercooked crustaceans or shellfish, whale meat, drinking water \\  & [11, 157, 159, 161, 164, 168, 169, 170, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 171, 160, 172, 173, 174] \\ \hline _Giardia intestinalis_ & Drinking water, fresh produce, composite ready-to-eat food, canned salmon, raw oysters, ice cream, noodle salad, chicken salad, dairy products, sandwic, tripe soup, \\  & unpasteurized milk, shellfish, unidentified foods [26, 29, 140, 147, 149, 154] \\ \hline _Trypanosoma cruzi_ & Acai juice, sugar cane juice, palm, guanabana, guava, milpesillo, majo, mango, mandarin, \\  & orange juices, raw meat [12, 251] \\ \hline _Balantiotides coli_ & None reported \\ \hline _Cyclospora cayetanensis_ & Berries, cilantro, basil, lettuce, ready-to-eat bagged salads, sugar snap peas [242, 237, 6, 238] \\ \hline _Cystoisospora belli_ & None reported \\ \hline _Sarrocystis_ spp. & Beef, pork, venison, whale meat [173, 260] \\ \hline _Blastocystis hominis_ & None reported \\ \hline _Endolimax nana_ & None reported \\ \hline \end{tabular}
\end{table} 
Table 1: Sources of pathogenic protozoans involved in infection cases and outbreaks according to literature published since 2019.