Disease and Discrimination
February 26, 1999
The Most Common STD Which No One Knows About
Human papillomavirus (HPV) is one of the most common sexually transmitted diseases (STDs) in the United States, however, few people know about the disease; those who do know about it have limited information because of the general lack of knowledge about HPV. Twenty-four to forty million Americans have been infected by HPV at some point in their life, with a new infection rate of 1 million annually. In addition, 60% of United States college students are reported to have been exposed to the virus. However, these statistics are slightly unreliable because HPV is not a reportable disease. Some scientists estimate that for every one case of visible, external genital warts there are two subclinical, undetected cases of HPV. The actual prevalence of the disease is probably higher than the reported figures.
HPV is spread through skin, not bodily fluids, and is the result of skin-to-skin contact. Although genital contact is the most common form of transmission, HPV can be transmitted to and from mouth, throat, and anus, as well as from mother to fetus. Skin-to-skin contact with the area of a person's body infected with external genital warts results in a 60% to 90% chance of contracting the virus. In one study at the University of Washington, researchers determined that 20% of female college students contracted HPV after their first sexual encounter and more than 90% of those infected women contracted another strain of HPV within two years. Risk factors for contracting the virus include multiple sexual partners, smoking, and the use of oral contraceptives. The lesions occur most frequently in women on the vulva, cervix, or rectum, and in men on the penis, scrotum, or rectum.
There are more than 80 varieties of the human papillomavirus, which infects epithelial cells at different locations on the body. The viruses are a part of two genuses of the family Papovaviridae and are distinguished from each other based on DNA homology. The life cycle of the virus is dependent upon the growth of the host epithelial cells and a given virus type tends to only infect a specific type of epithelial cells in one area of the body. For example, the virus that causes warts on hands and feet is not the same virus that causes genital warts. Genital HPV, which is induced by approximately one-third of the virus types, infects the area around the genitals or anus of both men and women. Genital warts are generally caused by HPV types 6, 11, 42, 43, and 44. The warts are considered dry warts, in order to distinguish them from the moist lesions of secondary syphilis. In the late 1980s, a strong link was also discovered between HPV types 16, 18, 31, 33, and 45 and cervical cancer. The manner in which the DNA incorporates itself into the epithelial cells is different depending on the type of virus and also effects the manifestation of the virus. For the virus types that cause cervical cancer, HPV DNA is integrated into the host cell's DNA which then produces a protein to maintain cell transformation. HPV DNA for the virus types that do not cause cervical cancer are not integrated into the host's DNA. Because the types of HPV that induce genital warts are different than the types that cause cervical cancer, genital warts and cervical cancer are not linked and a person's risk of cervical cancer is not higher if she has genital warts.
HPV infection can manifest itself in three different forms of genital warts: clinical, subclinical, and latent. Clinical HPV infection is limited to a genital lesion that causes symptoms such as itching, burning, pain, and tenderness, or is visible to the unaided eye. Subclinical infection requires a colposcope or microscope in order to be detected and can also be discovered through an abnormal Pap smear. The presence of HPV DNA in tissue without detectable symptoms or lesions is determined to be latent HPV infection, which is the most common clinical manifestation of the virus. A given individual may experience one or more varieties of virus manifestations with a given infection.
The incubation period for HPV is approximately three months, however the time between exposure and detection varies much more widely because people often do not know that they are infected, particularly if the infection is subclinical or latent. According to a study by the National Institute of Allergy and Infectious Diseases, nearly half of the women with HPV infection had no detectable symptoms. There is currently no way of determining how long the virus has been in a person's system, therefore the source of infection is often unknown. Researchers have not determined whether external genital warts are more infectious than subclinical or latent infection, or if the removal of warts decreases the chances for transmitting the virus.
Currently, it is not possible to culture HPV in cells, and as a result, researchers have used viral DNA detection as a method of determining whether the virus is present. Methods such as in situ hybridization, Southern blot hybridization, and polymerase chain reaction (PCR) have been used to determine the presence of HPV in a given sample. Hybridization methods tend to have a very low sensitivity and higher false-positive rates, whereas PCR has a high level of sensitivity and lower false-positive rates. Using these methods of detection, researchers have determined that the infection tends to cycle through periods of replication and viral production resulting in a patient having both positive and negative tests for the virus depending on the point in the cycle that she or he is tested. As a result, doctors cannot detect carriers of HPV infection and there are no practical screening tests available. In addition, medical tests are not able to determine which type or types of virus a person is infected with or how likely she or he is to develop cancer as a result of the infection. Even if it could be determined which type of virus was causing the infection, the viruses that tend to cause cervical are not guaranteed to cause cancer.
The current treatments for HPV do not destroy the virus, but rather remove the warts. Genital warts can cause psychological stress as well as pain and irritation. Patients who choose to have the warts remove do so in order to ameliorate the symptoms, not to cure the HPV because the treatment does not exterminate the virus. Often the treatments can be painful, disfiguring and impractical for patients because they require frequent doctor's visits. Each individual patient must weigh the benefits and drawbacks of receiving treatment.
In some cases the warts recur, but most people's immune systems are able to naturally decrease or eliminate recurrence over time. For some people, the immune system can actually clear the virus from the body over a period of time, however in other cases the virus remains in the body for life and tends to produce symptoms when the immune system is weakened. Researchers do not know what effect treatment efforts have, if any, on the natural progression of the virus.
The initial increase in the study of HPV was the result of the link between the virus and cervical cancer that was discovered in the late 1980s. HPV causes almost all cases of cervical cancer, which is the fourth deadliest form of cancer among women worldwide. Although the types of HPV that cause genital warts are different than the forms that cause cervical cancer, both forms of the virus have been the subject of increased research.
Even with the increased research around HPV, information about the virus is still quite limited. In 1997, the Center for Disease Control (CDC) budgeted $106 million for STDs, $139 million for breast and cervical cancer, and $616 million for HIV and AIDS. Although STDs affect many millions more people than HIV and AIDS, the lethality of AIDS has created decreased support for the exploration of other STDs. As a result, the costs for treating HPV exceeds $3.5 billion per year.
In one study of college students, only 2% of participants who had HPV recommended that their partners be evaluated for HPV. In addition, only one-third of the participants with HPV advised practicing safer sex. It is unclear whether this tendency to not protect sexual partners is the result of a lack of knowledge surrounding the transmission of HPV or whether it is the result of the stigma attached to STDs within our society.
Given the number of people infected with HPV, it becomes shocking to realize the lack of information available on the virus. Part of the problem is that the virus is not well understood by researchers, and it is therefore difficult to disseminate information to the general public. Many people have never heard of HPV until they are diagnosed. This trend in miseducation must change in order to decrease the effects of cervical cancer and genital warts. These educational efforts should be targeted towards younger people since HPV incidence is inversely related to age, with the highest rate among women ages 20 to 24 years.
Another problem with the control of HPV results from the method of transmission for the virus. Male condoms do not fully protect against contracting HPV because of possible scrotum and vulvar lesions. The female condom offers more protection because it covers a larger surface area, but skin-to-skin genital contact can still occur even with the use of a female condom. Therefore, in some cases abstinence becomes the only method of complete protection.
An incredible amount of money is currently being directed towards caring for the effects of this highly contagious sexually transmitted disease. In order to truly enable people to take responsibility for their sexual health, however, they must be educated about the virus before they contract it, rather than after. Accessible information must be provided about the high prevalence of HPV, means of transmission, the connection between HPV and cervical cancer, as well as availability and effectiveness of treatment. If money is put towards research and prevention, eventually the prevalence rate of HPV will drop and the cost of caring for the disease after people have contracted it will decrease as well. Until then, people will continue to get the virus and pass it on to their partners, often without ever knowing it, and end up costing society at large extensive amounts of money to clean up after a disaster that could have been prevented.
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