Infectious causes of cancerFrom Wikipedia, the free encyclopediaWorldwide 16.1% of cancers are related to infectious diseases.[1] This proportion varies in different reions of the world from a hih of !".#% in $u%&$aharan 'frica to !.!% in 'ustralia and (ew )ealand.[1] *iruses are the usual infectious aents that cause cancer %ut +yco%acterium, some other %acteria and parasites also have an effect.' virus that can cause cancer is called an oncovirus. These include human papillomavirus ,cervical carcinoma-, .pstein&/arr virus ,/&cell lymphoproliferative diseaseand nasopharyneal carcinoma-, 0aposi1s sarcoma herpesvirus ,0aposi1s $arcoma and primary effusion lymphomas-, hepatitis / and hepatitis 2 viruses ,hepatocellular carcinoma-, and 3uman T&cell leukemia virus&1 ,T&cell leukemias-. /acterial infection may also increase the risk of cancer, as seen in Helicobacter pylori&induced astric carcinoma.["] 4arasitic infections stronly associated with cancer include Schistosoma haematobium ,s5uamous cell carcinoma of the %ladder- and the liver flukes, Opisthorchis viverrini and Clonorchis sinensis ,cholaniocarcinoma-.[!]Contents[hide] 1+yco%acterium "*iruses !/acteria 64arasites 7$ee also 68eferencesMycobacterium[edit]Tu%erculosis is a risk factor for lun cancer.[6]Viruses[edit]'ccordin to some authors, viruses are one of the most important risks factor for cancer development in humans, second only to to%acco use.[7]There are two types of cancers caused %y viruses9 acutely transforming or slowly transforming cancers. :n acutely transformin viruses, the virus carries anoveractive oncoene, and the infected cell %ecomes cancerous as soon as the overactive viral ene is e;pressed. :n contrast, in slowly transformin viruses, the virus enome is inserted near a previously e;istin proto&oncoene in the enome of the infected cell. The virus causes overe;pression of that proto&oncoene, which typically induces uncontrolled cell division. /ecause the virus1 enes miht not insert near enouh to a proto&oncoene to trier the cancerous chanes[citation needed] and, even if optimally located, it miht take some time to %ecome activated, slowly transformin viruses usually cause tumors much loner after infection than the acutely transformin viruses, if at all.:nfection %y some hepatitis viruses, especially hepatitis / and hepatitis 2, can induce a chronic viral infection that leads to liver cancer in a%out 1 in "