HPV: The puzzling virus
The Human Papillomavirus (HPV) is considered as a major health threat for women worldwide. The majority of cervical cancer cases, by far, are thought to result from chronic infection with certain strains of HPV. The virus can be hidden for years from a woman’s immune system with no apparent symptoms — then awaken and create the deadly disease. This is called shy virus that puzzled scientists for many years. In 1983, Dr Harald zur Hausen of Germany discovered the association of HPV with cervical cancer for which he was awarded the Nobel Prize in Medicine in 2008.
HPV infects predominantly the cervix (lower part of uterus) and also can affect vagina and anus. Although it causes cancer in women, it can lead cancers of the anus and penis in men. It can also infect the mouth and throat. Over 100 different types of HPV have been identified so far. Some HPV types cause warts, but do not cause cancer; whereas, other types cause cancer, but do not cause warts. However, the majorities of viruses are considered harmless and have no symptoms. Most infected individuals do not know that they are infected and are passing the virus on to their sex partner. Very rarely, a pregnant woman with genital HPV can pass HPV to her baby during delivery.
About 40 types of HPV are typically transmitted through sexual contact. Persistent infection with high-risk HPV types (HPV-16,18,31,33 etc.) different from the ones that cause warts — may progress to pre-cancerous lesions and invasive cancer.
Most HPV infections in young females are temporary, 70 per cent of infections are gone in one year and 90 per cent in two years. But when infection persists, 5-10 percent of infected women develop pre-cancer, which can eventually progress to invasive cervical cancer. This process usually takes 15–20 years, providing opportunities for detection and potential treatment with high cure rates. There are several ways that one can lower the chances of getting HPV — practice of safer sex, faithful relationship and vaccines.
Visual Inspection using Acetic Acid (VIA) and Pap test are used to detect abnormal cells which may develop into cancer. A cervical examination also detects warts and other abnormal growths. Abnormal and cancerous areas can be removed with a simple procedure, typically with a cauterising loop or cryotherapy. New HPV DNA tests are now available that is more sensitive than Pap or visual inspection.
Cervical cancer screening has reduced the incidence and fatalities in the developed world, whereas, substantial death tolls are still associated with HVP infections in the developing countries like Bangladesh where the cancer ranked number one among cancers that affect females.
An immunologist working in a multinational health care company in the USA.
Source: The Daily Star, February 20, 2010