Cryptosporidium and Colon Cancer: Cause or Consequence?

Abstract

The number of cancers attributable to infectious agents represents over 20% of the global cancer burden. The apicomplexan intracellular parasite Cryptosporidium is currently considered one of the major causes of mild and severe diarrhea worldwide. However, less attention has been paid to its tumorigenic potential despite the high exposure of humans and animals to this ubiquitous parasite. Herein, we discuss the potential causal link between Cryptosporidium infection and digestive cancer, with particular emphasis on colon cancer, based on increasing clinical, epidemiological and experimental pieces of evidence supporting this association. In addition, we highlight the current knowledge about the potential mechanisms by which this parasite may contribute to cell transformation and parasite-induced cancer.

An Update on Zoonotic Cryptosporidium Species and Genotypes in Humans

“…The parasite has a complex life cycle that initiates upon ingestion and excystation of oocysts and involves both asexual and sexual phases, which culminate in the shedding of infectious thick-walled oocysts in faeces [ 14 ]. In humans, in addition to watery diarrhoea, cryptosporidiosis can cause abdominal pain, vomiting, headaches, joint pain, malnutrition, failure to thrive and cognitive deficits and has been linked with colon cancer [ 15 , 16 , 17 , 18 , 19 , 20 ]. Although usually self-limiting in immunocompetent hosts, cryptosporidiosis can become chronic, persisting for 2 years or more [ 5 , 17 ].…”

Bacterial and Parasitic Pathogens as Risk Factors for Cancers in the Gastrointestinal Tract: A Review of Current Epidemiological Knowledge

“…Infection occurs mainly through the fecal-oral pathway or through consumption/ingestion of contaminated food and water. Over 90% of the infections are caused by the species Cryptosporidium parvum and Cryptosporidium hominis ( Sawant et al, 2020 ). Cryptosporidium is known for its opportunistic behavior in immunocompromised patients (e.g., HIV-patients or individuals receiving oncological treatment) ( Kalantari et al, 2020 ).…”

Stressing a tired host: Cryptosporidium species and Helicobacter pylori infections in diabetes mellitus patients with gastrointestinal manifestations

“…cryptosporidiosis is increasing, and the frequency of infection is likely to be one hundred-fold higher than the number of reported cases [14] . Parasite oocysts are transmitted primarily through the fecal oral route [15] , and hence Cryptosporidium is responsible for several waterborne outbreaks of gastrointestinal disease [16][17][18] . The oocysts are highly infectious and are resistant to hard environmental conditions [19,20] .…”

“…In patients with immunodeficiencies, the biliary and respiratory tracts may also be involved [25,26] . A link between cryptosporidiosis and colorectal carcinoma was suggested [18] . Cholangiocarcinoma, complicating chronic cryptosporidiosis and cholangitis, was also postulated [27] .…”