They are the same culprits that cause infection in your body: viruses, parasites, and bacteria. These are responsible for nearly one-fifth of all cancers across the globe. Looking at data from 2002, about 18% of cancers were caused by viruses that trigger HIV, hepatitis, and stomach ulcers. Scientists believe that if we could prevent these infections, then a large chunk of worldwide cancers could be lopped off.

 Two million cases of cancer every year are attributable to infections. The worst offender? That’d be the H. pylori bacteria, which causes ulcers in your abdomen and contributes to stomach cancer. Back in 2002, it’s estimated that H. pylori was responsible for six percent of all cancer cases. Others include:

 – HPV: The “human papillomavirus” afflicts 20 million people and causes genital warts. Several strains of this infection can cause cervical cancer.

 – Hepatitis: Both the B and C viruses cause an astronomical 85% of all liver cancers. It’s worst in developing nations. In the U.S., it causes around 42% of all liver cancer cases.

 – EBV: The “Epstein-Barr” virus is very common; it’s a herpes-like infection that stays dormant in your immune system after you have contracted it. It is also linked to Hodgkin’s and non-Hodgkin’s lymphoma, as well as nasopharyngeal cancer.

 – HIV: The infamous virus that can cause AIDS can also trigger many cancers by damaging your immune system. They include cervical cancer, Kaposi’s sarcoma, and lymphoma.