HPV – human papillomavirus- infection and HPV related diseases - Times of India
HPV – a double stranded DNA virus, a common virus infecting the reproductive tract of both men and women and responsible for cancers, warts and death. It's a virus with more than 200 strains.
It causes cancer in parts of the body where HPV infects cells, such as in the cervix, oropharynx anus, penis, vagina, and vulva. The low risk types would cause warts in the same areas of the body.
Epidemiology:
Human papillomavirus (HPV) causes more than one-fourth of infection related cancers globally.
According to the National Cancer Registry Programme (NCRP) data – among all cancers, 7.5% were HPV related cancers. Cervical cancer (87.6%) and oropharyngeal cancer (63.2%) were the most common HPV related cancers in India among females and males respectively. Worldwide data of HPV-related cancers : High-risk HPVs cause about 5% of all cancers worldwide, with an estimated 570,000 women and 60,000 men getting an HPV-related cancer each year. Cervical cancer is among the most common cancers and a leading cause of cancer-related deaths in low- and middle-income countries, where screening tests and treatment of early cervical cell changes are not readily available. In the United States, high-risk HPVs cause 3% of all cancers in women and 2% of all cancers in men, according to the Centers for Disease Control (CDC).
Transmission:
Primary mode of transmission is through any intimate skin-to-skin contact and sexually transmitted via vaginal, anal, or oral sex.
HPV infection is common and nearly all sexually active people are infected with HPV within months to a few years of becoming sexually active. Almost 50% of these are with a high-risk HPV type and can infect both males and females.
It is not transmitted by hugging, holding hands, swimming pool, hot tubs, sharing food, toilet seats. Condoms and dental dams can lower the chance of HPV transmission but do not prevent it completely.
Pathophysiology :
Every HPV infection does not lead to cancers. Most of the time the immune system controls HPV infections and clears it. However sometimes HPV infections are not successfully controlled by our immune system and high-risk HPV infection may persists for many years, leading to cell changes that, if untreated, may eventually become malignant. The atypical cellular changes to eventually develop into cancer would take 15-20 years in normal individuals and 5-10 years in immunocompromised people. This gives a long window for detection of the disease and the changes, where the cellular changes can be detected easily with regular Pap smear or HPV genotyping and timely treatment can be given to prevent cancers.
They are of two types of HPV-
Low risk and high risk.
- Low-risk HPVs– usulayy cause no disease. And a few may cause ano genital or oral warts.
- High-risk HPVs – responsible for causing several types of cancer. There are about 14 high-risk HPV types including HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68. Of these, HPV16 and HPV18, cause most HPV-related cancers.
HPV infects the squamous cells that line the inner surfaces of these organs. For this reason, most HPV-related cancers are a type of cancer called squamous cell carcinoma. Some cervical cancers come from HPV infection of gland cells in the cervix and are called adenocarcinomas
Risk factors:
High risk for infection would be immunocompromised status, co-infection with Sexually Transmitted Infections (STI), homosexuals, smoking, multiple sexual partners.
Signs and symptoms:
Most of HPV associated cancer lesions remain asymptomatic. The precancerous cell changes caused by a persistent HPV infection at the cervix rarely cause symptoms, which is why regular cervical cancer screening is important. Precancerous lesions at other sites in the body may cause symptoms like itching or bleeding. If an HPV infection develops into cancer, the cancer may cause symptoms like bleeding, pain, foul smelling discharge or swollen glands. Some cause warts which can cause disfiguring, itching dryness and pain at sexual contact.
Treatment:
There is no treatment for HPV, but in most cases it goes away without treatment.
Precancerous vaginal, vulvar, penile, and anal lesions and genital warts: Treatment methods include topical medicines, surgical excision, cryosurgery, and laser therapy or excision
Precancerous cervical cell changes- loop electrosurgical excision procedure (LEEP), which is a method to remove the abnormal tissue.
Once cancerous changes develop it has to be treated as other non HPV related cancers with standard treatment protocols.
Prevention
HPV vaccination provides strong protection against new HPV infections. Vaccination is prevention and does not cure an infection once you have it. The HPV vaccine is not used to treat HPV infections or diseases caused by HPV. HPV vaccination offers the most protection when given at ages 9-12. HPV vaccination is estimated to prevent up to 90% of HPV-related cancers.
Three HPV vaccines—9-valent HPV vaccine (Gardasil 9, 9vHPV), quadrivalent HPV vaccine (Gardasil, 4vHPV), and bivalent HPV vaccine (Cervarix, 2vHPV)—have been licensed by the U.S. Food and Drug Administration (FDA). All three HPV vaccines protect against HPV types 16 and 18 that cause most HPV cancers. The HPV vaccine Gardasil 9® protects against infection from nine HPV types: the two low-risk HPV types that cause most genital warts, plus the seven high-risk HPV types that cause most HPV-related cancers.
All HPV vaccines have been found to have high efficacy (close to 100%) for prevention of HPV vaccine type-related persistent infection, cervical intraepithelial neoplasia (CIN) 2/3, and adenocarcinoma in situ (AIS) in clinical trials .
- Children aged 9 through 14 years who have received two doses of HPV vaccine less than 5 months apart will need a third dose.
- Three doses are also recommended for people aged 9 through 26 years who have weakened immune systems.
Efficacy of vaccination :
- Since HPV vaccination was first recommended in 2006, infections with HPV types that cause most HPV cancers and genital warts have dropped 88% among teen girls and 81% among young adult women.
- Fewer teens and young adults are getting genital warts.
- HPV vaccination has also reduced the number of cases of precancers of the cervix in young women.
- The protection provided by HPV vaccines lasts a long time. People who received HPV vaccines were followed for at least about 12 years, and their protection against HPV has remained high with no evidence of decreasing over time.
Screening for HPV and cell changes caused by HPV
Screening tests are used to check for disease when there are no symptoms. The goal of screening for cervical cancer is to find precancerous cell changes at an early stage, before they become cancer and when treatment can prevent cancer from developing.
Disclaimer
Views expressed above are the author's own.
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