# Food and Drinking Water as Sources of Pathogenic Protozoans: An Update
## 4 _Cryptosporidium_ spp.
### Diseases Caused by Cryptosporidium _spp_  
Cryptosporidium are carried asymptomatically or cause acute diarrhea that, in immunocompetent hosts, is self-limiting and lasts for 3-12 days [10]. However, the infection can be life-threatening in immunocompromised patients and is the primary cause of chronic diarrhea that increases the mortality rates in HIV-infected patients with acquired immunodeficiency syndrome (AIDS) [105]. In these patients, _Cryptosporidium_ spp. can cause biliary tree inflammation and biliary tract blockage, sclerosing cholangitis, papillary stenosis, and pancreatitis [106,107]. In southern Africa, cryptosporidiumosis showed a higher pooled prevalence in HIV/AIDS patients (25.2%) compared to children (20.5%) and diarrhoea individuals (17.9%) [92]. In children with primary immunodeficiency _Cryptosporidium_ spp. caused sclerosing cholangitis and pulmonary infections [108]. In AIDS patients, _Cryptosporidium_ spp. were isolated also from the respiratory tract, including bronchioles [10]. The prevalence of cryptosporidiumis in HIV-infected individuals ranged from 5.6% to 25.7% in Africa, 3.7% to 45.0% in Asia, 5.6% to 41.6% in South America, and 2.6% to 15.1% in Europe [101]. Higher infection rates and more severe clinical outcomes were seen in HIV-positive individuals with CD4+ cell counts lower than 200 cells/uL [105]. In AIDS patients and children, _C. parvum_ is less virulent than _C. hominis_ and has been mostly associated with vomiting and chronic diarrhea [10]. _Cryptosporidium_ infections in immunocompromised subjects should not be treated with the only approved drug, nitazoxanide, that can be safely administered to immunocompetent patients only. Moreover, there are presently no vaccines available [108, 109, 110]. Some studies reported a higher prevalence of cryptosporidiosis in immunocompromised patients. In a case-control study performed in western Iran, this infection was significantly more prevalent in CRC patients [111]. In low- and middle-income countries, cryptosporidiumis was reported to be more frequent in hemodialysis and renal transplant patients. Instead, in industrialized nations, it occurs in individuals of various ages and immune statuses [101]. In particular, in France, cryptosporidiosis cases--previously more frequent in immune-deficient patients--became dominant in immunocompetent individuals after 2019, possibly as an effect of the improvement in monitoring [90]. The most common sequelae of cryptosporidiosis are long-lasting diarrhea (25%), abdominal pain (25%), nausea (24%), fatigue (24%), and headache (21%). Symptoms meeting the definition for IBS were described in 10% of cases for up to 36 months, more frequently in children than in adults [28]. Massive _C. hominis_ infection with chronic diarrhea, large intestine-cryptitis and damage of lamina propria, joint-related symptoms, and chronic urtic in immunocompetent individuals were recently reported [112, 113, 114, 115]. Diarrhea is a common problem in solid organ transplanted patients, with a prevalence of 20-50%. A large proportion of diarrhea cases in liver transplanted patients was caused by _Cryptosporidium_ spp. but the lack of vigilance and awareness led to delays in diagnosis and treatment, resulting in immune rejection and shock. Inappropriate treatments with antibiotics and antifungals led to septic shock and multiorgan functional impairment in a 55-year-old Chinese man with long-lasting diarrhea of food origin. After ten days of hospitalization, _Cryptosporidium_ oocytes were detected in stool, and the organism was detected in blood by new generation sequencing (NGS), so the infection was successfully treated with nitazoxanide [108]. In a case-control study carried out in China, a correlation was found between _C. parvum_ infection and CRC, liver cancer, and esophageal and small intestine cancers, with infection rates of 40%, 6.25%, 17.24%, and 14.29%, respectively. The isolates showed 18S rRNA sequences identical to those of cattle isolates, suggesting zoonotic transmission. _C.