What is hpv virus?
HPV
6% ~ 7% of women have been infected with HPV? Viral infection
People, especially women, have been worried about cervical cancer for a long time. In fact, cervical cancer is not terrible. It is the only cancer that can be effectively prevented, found early and treated early among all cancers. Most women who are afraid of cervical cancer stem from their lack of knowledge about cervical cancer.
Modern medicine has confirmed that the cervical cancer of women is caused by human papillomavirus (HPV) infection. Although there is a correlation between cervical cancer and HPV, not all women infected with HPV will develop cervical cancer.
Because HPV is widely distributed in nature, human skin, digestive tract, respiratory tract and so on all carry this virus. Therefore, all women who have sexual life may bring HPV into their reproductive tract through sexual contact. Medical workers have conducted a general survey of women aged 18-28 and found that HPV infection is not uncommon. Experts speculate that as far as women are concerned, the cumulative lifetime infection rate of hpv can be as high as 6% ~ 7%. In other words, 6% ~ 7% of women have been infected with HPV in their lifetime, but this infection is usually transient.
Because when people are infected with this virus, the body will gradually become immune to the virus, and a few patients will soon form immunity to the virus. When the immunity is strong enough, HPV will be eliminated. Therefore, a large number of medical statistics show that although the proportion of people infected with HPV is large, most of them are transient, that is, the virus will disappear naturally in 1-2 years (generally referring to HPV infection). Most women's immune system can eliminate HPV entering the body, and only a few women with weak immune function can't eliminate HPV entering the body, resulting in HPV persistent infection, but this process takes about 8 to 12 years before it can develop into cervical cancer.
Almost all the patients with cervical cancer found in clinic are women over 3 years old. Therefore, women who have sex can start HPV-DNA testing after the age of 3. The test result is negative, which means that it has not been? HPV infection, so there will be no risk of cervical cancer for a long time. Therefore, this inspection can be done every three years. If the test result is positive, it may not necessarily develop into cervical cancer, because the immune system in the body may destroy the virus. It is only possible to develop into cervical cancer. Therefore, a cervical smear should be done first to see if there are any abnormal cervical cells at present. If not, these two inspections should be reviewed annually. Once the abnormality is found, it can be treated immediately, so that cervical cancer can be eliminated in the bud.
Therefore, as far as women are concerned, hpv infection has strong universality and self-limitation. Even if you are infected with HPV, there is nothing to be afraid of. Usually, the human body can gradually remove it. Women with a little immunity can completely avoid the occurrence of cervical cancer by doing regular gynecological examinations and cancer screening every year.
Human papillomavirus (human? Papillomavirus (HPV) is an epitheliophilic virus with high specificity. For a long time, it has been known that HPV can cause benign tumors and warts in human beings, such as human common warts, condyloma acuminatum and papilloma on mucosa near reproductive organs. HPV is a species-specific epitheliophilic virus, which belongs to a small DNA virus with double-stranded closed loop and contains about 8 base pairs. It includes 8 early open reading frames (E1-E8), 2 late reading frames and 1 non-coding long control area. In the early open reading frame, E6 and E7 genes are the most important to stimulate cell growth, and E6 and E7 proteins encoded by E6 and E7 cause the immortalization of cervical epithelial cells. The late reading frame L1 and L2 genes respectively encode the major and minor capsid proteins of HPV, which are assembled into the capsid of HPV. Since 1976 zur? Since Hansen put forward that HPV may be a carcinogenic factor of sexually transmitted diseases, the research on the relationship between HPV infection and cervical cancer has become a hot topic in the study of tumor virus etiology. ?
There is no special drug treatment for HPV. In fact, there is no drug for virus treatment. Interferon and others all improve immunity and do not directly correspond to viruses. HPV is easy to spread, but HPV is not equal to cancer. Especially, most people heal themselves within one or two years when there are HPV antibodies in the blood only indicating that they have been infected with HPV, and HPV is found in secretions or exfoliated objects such as cervix. Sexually transmitted diseases are generally considered as sexual contact infection, or contact with secretions (including sweat) of sexually transmitted diseases patients, and are not transmitted through the air. This is because people's resistance is limited, and too strong invasion may not be able to resist, which does not mean that all viruses can cause diseases. The venereal warts commonly known as "cauliflower" are caused by HPV infection, and women may get cervical cancer after warts occur. Three steps, HPV infection-self-healing or developing into warts or concealed-long-term infection increases. After all, in addition to life, women also want to maintain normal functions, early treatment, little damage, and can not affect their lives. At the same time, it should also be pointed out that it is not the cause of sexual life-HPV- cervical cancer, but unmarried women may also suffer from cervical cancer, of course, the probability will be much smaller.
Of course, some people take this as an argument. coburn, an American obstetrician and Congressman, regards HPV as another AIDS crisis. He suggested that the condom package should state that the products can't prevent HPV, so that women can know that condoms can't resist the virus that can cause cervical cancer. ? As a virus, especially a widely spread virus, HPV should have special disinfection and prevention procedures to ensure that condoms can prevent the spread of the virus. Simply put, tap water (with chlorine) is soaked for one night, basked in the sun during the day and reused at night, which is absolutely anti-HPV. However, if you have the time, it is better to eat well, exercise more, rest more, have better immunity, and be less prone to HPV infection.
HPV is the general name of a group of viruses, which belong to a family. The virus morphology is similar, but the DNA restriction endonuclease map is different, and the antigenicity of the nuclear shell protein is different. The results under the electron microscope are shown in Figure 1. At present, there are about 8 types of HPV, which can be divided into skin-type HPV and genital epithelial HPV according to the location of infected epithelium. About 35 types can infect women's reproductive tract, and about 2 types are related to tumors (HPV infections mentioned below are all female reproductive tract infections). According to the different types of HPV and the risk of tumor occurrence, it is divided into low-risk types and high-risk types of HPV. The low-risk types of HPV include HPV6, 11, 42, 43, 44, etc., which often cause benign lesions such as external genital condyloma, including low-grade cervical intraepithelial lesions (CIN? I), high-risk HPV types include HPV16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, etc., which are associated with cervical cancer and cervical intraepithelial lesions (CIN? II/III), especially HPV16 types 16 and 18. ?
2. what is the prevalence rate of HPV infection in female reproductive tract?
With regard to the study on the prevalence rate of HPV infection, the positive rate of HPV infection reported in each study is different due to the differences in the source of test specimens, the HPV detection technology used, the types of HPV detection and the population differences in the study area. By testing HPV? The infection rate determined by DNA method is slightly higher, but it is very low by cytology or colposcopy. Many direct detection methods, such as nucleic acid blot in situ hybridization or dot blot hybridization, detect that the infection rate is about 1-2%, and the result by PCR is higher. The female college students in a university (97% have had sex, and the average number of sexual partners is 4) were examined. The results showed that the PCR method was 46%, while the dot blot hybridization method was only 11%, which showed that the detection method affected the detection of HPV infection. In the experiment of Melkert., the detection rate by PCR was 4.1% in ordinary women; Herrero reported in Costa? The positive rate of HPV infection in women aged 18-94 in rural areas of Rica was 16%. At present, many studies use HC method to detect HPV. DNA, this method is more sensitive, so the detection rate is higher. Clavel? C et al. detected the HPV infection status of 1,518 women aged 15-72 by HC-II method, and found that the positive rate of HPV infection was 22.3%. ?
3. age distribution?
The infection rate of p>HPV mainly depends on people's age and sexual habits. Many studies have found that the infection rate of HPV among sexually active young women is the highest, and the peak age is 18-28 years old, which decreases obviously with the increase of age, but most data reports do not distinguish between high-risk and low-risk types, as shown in Figure 2. Most HPV infections can disappear in a short period of time, and the virus is gradually eliminated by the body through the autoimmune system, especially the low-risk type HPV is easier to be eliminated by the body, which lasts for about 18 months, so the positive rate of low-risk type HPV infection shows a downward trend. However, for high-risk HPV infection, many studies report that the peak age of infection is 2-3 years old. At this stage, the infection rate is temporary and high, reaching 25-3%. After that, the infection rate gradually decreases, and 5-1% of high-risk HPV infection is continuous after 35 years old. There are still some disputes about whether the positive rate of HPV infection begins to rise or fall after the age of 4, and more detailed data are needed to verify it. ?
4. what are the epidemic factors of HPV infection?
Because HPV infection usually has no obvious clinical symptoms, its detection rate varies with various methods, so it is difficult to determine the epidemiological factors of HPV infection. However, it is clear that HPV infection is a sexually transmitted disease, which is related to sexual behavior factors. However, good personal hygiene, attention to menstrual hygiene, hygiene before and after the same room, and the use of intrauterine devices can reduce the probability of HPV infection. ?
(1) Sexual behavior: Most studies show that the number of women's recent sexual partners, the frequency of sexual intercourse, and the genital warts of sexual partners are closely related to HPV infection. Although some studies show that the age of first sexual intercourse is also related to HPV infection, this factor is affected by the number of sexual partners, and its risk is not significant after adjusting the number of sexual partners.
(2) Immune factors: The host's immunity plays a great role in the progress of HPV infection and lesions. Studies have found that the infection rate of HPV in immunosuppressants with kidney transplantation is 17 times that of normal people. The infection rate of HPV among people infected with HIV also increased. Because of the chaotic sexual behavior of HIV-infected people, the large number of partners and the young age of first sexual intercourse, the probability of HPV infection increases. However, some studies can't prove that there is a direct correlation between immunosuppression and HPV infection. The HIV population may increase the HPV infection rate because of the high risk of self-exposure or the decreased ability of the body to resist latent viruses. The detection level of DNA is higher than that of normal people, which indicates that the ability of the body to inhibit HPV infection is reduced.
(3) Pregnancy: Studies have shown that the increased number of pregnancies, deliveries and miscarriages of women do not increase the risk of HPV infection, but the number of teratomas is related to HPV infection. Some studies show that the infection rate of HPV in pregnant women is high, and the amount of virus detected is also increased, but this may be due to the increase of virus level during pregnancy, which improves the detection efficiency. A study on the detection of HPV by PCR confirmed this view. The detection of HPV by PCR was independent of the virus content, and it was found that there was no significant difference in the infection rate between pregnant and non-pregnant women (9.6%/1.9%).
(4) Oral contraceptives: Although oral contraceptives can increase the risk of cervical cancer, whether it affects HPV infection is still controversial. Studies have shown that oral contraceptives can indeed increase the probability of HPV infection, but some people think that oral contraceptives have no effect on the occurrence of low-grade cervical lesions, but they can increase the risk of high-grade cervical lesions. Therefore, oral contraceptives are believed to change the progress of the disease rather than directly affect the HPV infection rate. ?
5.HPV infection and the risk of cervical cancer?
The relationship between HPV infection and cervical cancer was first put forward in the 197s, and many epidemiological and molecular studies have undoubtedly confirmed the etiological relationship between HPV and cervical cancer. Bosch and Manos collected cervical cancer biopsy samples from 22 countries for PCR detection, and found that HPV can be detected in 99.7% of tumors? DNA, and there is no significant difference between countries. This is the highest detection percentage of human tumor pathogenic factors reported so far, and it also shows that the correlation between HPV infection and cervical cancer is of universal significance. ?
Case-control study is an analytical epidemiological method to test the hypothesis of etiology. Whether it is a large-scale epidemiological study in Latin America with low accuracy detection technology (FISH) or a study with high sensitivity detection technology (PCR, HC-II), all the results show that HPV infection has obvious correlation with cervical cancer (OR=3.6-254.2), especially HPV types 16 and 18. A population-based case-control study conducted by Muňoz et al. in Colombia and Spain (the incidence of cervical cancer is 8 times higher in the former than in the latter) included 436 histologically confirmed cases and 387 randomly selected cases as controls from the population where the cases were located. At the same time, three HPV types were used. DNA detection technology (ViraPap, SH? And PCR). This study avoids the selective deviation of population and region, and at the same time takes into account the differences between detection technologies. After adjusting some confounding factors, all three detection methods reach the same conclusion: HPV types 16, 18, 31, 33 and 35 are strongly correlated with cervical cancer in two countries, suggesting that HPV and cervical cancer have a causal relationship. Cohort study is another important analytical epidemiological method used to verify the hypothesis of disease etiology, which can directly reflect the time sequence of HPV infection and cervical cancer, and more effectively verify the hypothesis of disease etiology. Campion for 1 cases of mild cervical intraepithelial lesions (CIN? I) After more than two years of follow-up, 56% of HPV16 16,18 positive patients developed into severe cervical intraepithelial lesions (CIN? III), while only 2% of the subjects with positive HPV6 progressed. Murthy et al. showed that 63 cases of cervical atypical hyperplasia developed into carcinoma in situ, and the positive rate of HPV16/18 in tissue samples was 68.3%, while the positive rate of 44 cases of non-progressive atypical hyperplasia was 27.3%, and the relative risk was 5.9 (95% CI: 2.5-14.1), which had significant statistical significance. In addition, strong evidence of human papillomavirus carcinogenesis has been obtained in cytology and molecular biology. In 1995, WHO and IARC identified HPV as the cause of cervical cancer. ?
6.HPV types and cervical cancer?
HPV infection in reproductive tract is the most common.