Cervical cancer is unrelated to viral infection.

Cervical cancer had long shown hints of an infectious cause. Its occurrence was linked to patterns of sexual exposure, but for decades researchers could not identify a specific infectious agent.

Harald zur Hausen proposed that particular types of human papillomavirus might be responsible. HPV is a large family of viruses that infect skin and mucous membranes. Most infections are temporary and cause no cancer.

In 1983, zur Hausen’s group found DNA from HPV16 in cervical-cancer tissue, followed soon afterward by HPV18. These and several related types are now called high-risk HPV because persistent infection can interfere with proteins that normally control cell division and prevent damaged cells from multiplying.

Large epidemiological studies then showed that persistent high-risk HPV infection is present in essentially all cervical cancers.

The distinction between infection and cancer matters. HPV infection is extremely common, and most infections disappear without treatment. Cancer usually requires a high-risk infection that persists for years and accumulates additional cellular changes.

That discovery also changed prevention. Vaccination can prevent infection by major high-risk HPV types, while HPV testing can identify persistent infections before cancer develops.