Role of Protozoans in Causing Cancer in Human

Infections are found as one of the causes of cancer with almost every group of microorganisms involved. Some of these infections developing cancers are continuously being transmitted in society. International Agency for Research on Cancer (IARC) has certified certain microorganisms developing cancer in humans. Protozoans are one of them. They are eukaryotic, unicellular, anthroponotic microorganisms. Protozoans cause cancer in humans via the insertion and integration of their DNA sequences in the host cells stimulating cell division and proliferation by the release of reactive oxygen and nitrogen radicals developing DNA damage and p53 gene inhibition. This review discusses some cancer-causing protozoan parasites like Plasmodium falciparum, Leishmania donovani, Trypanosoma brucie, Toxoplasma gondii, Trichomonas vaginalis, Blastocystis hominis, Theileria microti and Cryptosporidium parvum in the light of recent researches done so far in the field of microbial origin of cancer.