Determinants of genital human papillomavirus infection in low-income women in Washington, D.C

Determinants of low-risk and high-risk cervical human papillomavirus infections in Montreal University students

BACKGROUND

Previous studies have been inconsistent about the degree of sexual transmissibility of cervical human papillomavirus (HPV) infection. The authors hypothesize that risk factors for HPV infection vary according to HPV type.

GOAL

To estimate the prevalence of HPV infection in asymptomatic women and to identify risk factors for overall HPV infection and HPV infection by oncogenic and nononcogenic type.

STUDY DESIGN

A cross-sectional survey was conducted at the McGill University clinic in Montreal. Cervical specimens were collected from 489 female students presenting at the clinic for a routine Papanicolaou test. Data on potential risk factors was obtained by questionnaire. Human papillomavirus DNA was detected by the polymerase chain reaction using consensus primers (MY09/11) followed by hybridization with generic and type-specific probes using Southern blot and dot blot techniques.

RESULTS

The overall HPV prevalence was 21.8%. A low-risk HPV infection was found in 6.2% of the women, 11.8% had a high-risk HPV infection (types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58), 7.1% had an unknown HPV type, and 2.7% had a multiple type infection. Two profiles emerged for sexual activity and risk of HPV infection according to oncogenic risk after multivariate analysis. Lifetime frequency of sexual intercourse and lifetime number of oral sex partners was associated with high-oncogenic-risk HPV infections; however, HPV infection with low-oncogenic-risk types was invariant with respect to markers of sexual activity.

CONCLUSION

These results suggest that there are differences in epidemiologic correlates of transmission between low-risk and high-oncogenic-risk HPV types based on oncogenicity. This finding has important implications for primary prevention of HPV infection and cervical cancer precursors.

The serological response to papillomaviruses

The antibody response to papillomaviruses is a key determinant of protective immunity. HPV serology is also an important epidemiological tool for the assay of past and present HPV infections and for prediction of HPV-associated cancers and their precursor lesions. This review focuses on the assay of antibody responses to the HPV capsid, its use as a marker of cumulative HPV exposure and surveys how HPV seroepidemiology has been used to elucidate the spread of HPV infection in various populations, the natural history of HPV infection and that exposure to HPV is associated with increased risk for several human cancers.

Serological evidence for protection by human papillomavirus (HPV) type 6 infection against HPV type 16 cervical carcinogenesis

Human papillomavirus (HPV) exists as more than 100 genotypes. It is not well-established whether the different HPV types interfere with infection or pathogenesis by each other. Possible interactions in cervical carcinogenesis between infection with the most common HPV types (6, 11, 16, 18 and 33) were studied in a seroepidemiological case- control study of 218 women with primary untreated cervical cancer and 219 healthy age-matched control women. As previously shown, HPV-16 seropositivity was associated with cervical cancer risk [odds ratio (OR), 2.39], but HPV-16 was not associated with cervical cancer risk among HPV-6 seropositive women (OR, 1.0). The relative excess risk due to interaction between HPV-6 and -16 was -2. 35 (95% confidence interval, -0.04 to -4.65), indicating significant antagonism. The results suggest that infection with HPV-6 may interfere with HPV-16-associated cervical carcinogenesis.

Risk factors for the acquisition of genital warts: are condoms protective?

OBJECTIVES

To characterise risk factors for the acquisition of genital warts and specifically to determine whether condoms confer protection from infection.

METHODS

A retrospective case-control study comparing demographic, behavioural, and sexual factors in men and women with and without newly diagnosed genital warts, who attended Sydney Sexual Health Centre (SSHC), an inner city public sexual health centre, in 1996. Data were extracted from the SSHC database. Crude odds ratios (OR) were calculated to compare cases and controls and significant factors were then controlled for using multivariate logistic regression to obtain adjusted odds ratios (ORs).

RESULTS

977 patients with warts and 977 controls matched by sex and date of attendance were included. In both sexes, univariate analysis revealed that younger age, more lifetime sexual partners, failure to use condoms, greater cigarette smoking and alcohol consumption were associated with warts, and there was a negative association with previous infection with Chlamydia trachomatis, Neisseria gonorrhoeae, hepatitis B, and genital herpes. In males, on multivariate analysis, factors which remained significant were younger age, more lifetime sexual partners; failure to use condoms, greater cigarette smoking, and previous chlamydia. In women, factors which remained significant were younger age, more lifetime sexual partners, condom use, marital status, and previous infections with Chlamydia trachomatis and herpes.

CONCLUSIONS

Independent risk factors for genital warts include younger age, greater number of lifetime sexual partners, and smoking. Consistent condom use significantly reduces the risk of acquiring genital warts.

Smoking and hormone-related disorders

Through its antiestrogenic effect, cigarette smoking is linked to a variety of hormone-related disorders, both benign and malignant. Diseases that depend on this hormone for growth and development tend to be less common among smokers, such as endometrial cancer and uterine fibroids. Some normal, estrogen-dependent physiologic processes are affected by smoking, making osteoporosis and premature menopause more common among women who smoke. In other disorders, the link between sex hormone levels, cigarette smoking, and disease development is less clear.

Detection of human papillomavirus DNA in cytologically normal women and subsequent cervical squamous intraepithelial lesions

BACKGROUND

Human papillomavirus (HPV) infection has been strongly associated with cervical carcinoma and its cytologic precursors, squamous intraepithelial lesions (SIL). We investigated the risk of SIL prospectively following polymerase chain reaction (PCR)-based DNA testing for a wide range of genital HPV types in a cohort of initially cytologically normal women, to clarify the role of HPV in the etiology of SIL.

METHODS

Starting in April 1989, 17,654 women who were receiving routine cytologic screening at Kaiser Permanente (Portland, OR) were followed for the development of incident SIL. During follow-up, 380 incident case patients and 1037 matched control subjects were eligible for this nested case-control study. Cervical lavages collected at enrollment and, later, at the time of case diagnosis (or the corresponding time for selection of control subjects) were tested for HPV DNA using a PCR-based method. The data were analyzed as contingency tables with two-sided P values or, for multivariable analyses, using odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

In comparison with initially HPV-negative women, women who tested positive for HPV DNA at enrollment were 3.8 times (95% CI = 2.6-5.5) more likely to have low-grade SIL subsequently diagnosed for the first time during follow-up and 12.7 times more likely (95% CI = 6.2-25.9) to develop high-grade SIL. At the time of diagnosis, the cross-sectional association of HPV DNA and SIL was extremely strong (OR = 44.4 and 95% CI = 24.2-81.5 for low-grade SIL and OR = 67.1 and 95% CI = 19.3-233.7 for high-grade SIL). HPV16 was the virus type most predictive of SIL, even low-grade SIL.

CONCLUSIONS

These findings are consistent with the hypothesis that HPV infection is the primary cause of cervical neoplasia. Furthermore, they support HPV vaccine research to prevent cervical cancer and efforts to develop HPV DNA diagnostic tests.

Advances in the diagnosis and treatment of human papillomavirus infections

During the past decade, much has been learned about the natural history of HPV. Most infections occur early in one's sexual life. The overwhelming majority of infections are cleared by the host immune system and never present as warts or neoplasia. Certain patient behavior such as smoking, frequent sex with many different partners, other STD infections, especially HIV, and immune-suppressive drugs promote HPV expression and cause persistent infection. Persistent HPV infection is very strongly related to neoplasia. In addition to high-risk HPV types, variant subtypes have been identified that interact with the host immune system to subvert host immunity and encourage viral persistence. New treatment programs rely on drugs that modulate the immune system and disrupt viral persistence. There is a real possibility of HPV vaccines in the future, which may protect the unexposed patient.

A survey of seroprevalence of human papillomavirus types 16, 18 and 33 among children

The importance and natural history of HPV infections in childhood is incompletely understood. We performed a survey for presence of serum antibodies to HPV capsids among 1031 children aged 0 to 13 years, resident in Stockholm, Sweden. The HPV seroprevalence among these children was 3.0% for HPV16, 0.6% for HPV18 and 2.7% for HPV33. By comparison, among simultaneously analyzed positive control panels comprising women with CIN or healthy women with type-specific cervical HPV DNA, seroprevalence of HPV 16, 18 and 33 was 69%, 58% and 63% respectively. The results suggest that HPV infection in childhood is not common.

Cervicovaginal human papillomavirus infection in human immunodeficiency virus-1 (HIV)-positive and high-risk HIV-negative women

BACKGROUND

Human papillomavirus (HPV) infection is associated with precancerous cervical squamous intraepithelial lesions commonly seen among women infected with human immunodeficiency virus-1 (HIV). We characterized HPV infection in a large cohort of HIV-positive and HIV-negative women participating in the Women's Interagency HIV Study to determine the prevalence of and risk factors for cervicovaginal HPV infection in HIV-positive women.

METHODS

HIV-positive (n = 1778) and HIV-negative (n = 500) women were tested at enrollment for the presence of HPV DNA in a cervicovaginal lavage specimen. Blood samples were tested for HIV antibody status, level of CD4-positive T cells, and HIV RNA load (copies/mL). An interview detailing risk factors was conducted. Univariate and multivariate analyses were performed.

RESULTS

Compared with HIV-negative women, HIV-positive women with a CD4+ cell count of less than 200/mm3 were at the highest risk of HPV infection, regardless of HIV RNA load (odds ratio [OR] = 10.13; 95% confidence interval [CI] = 7.32-14.04), followed by women with a CD4+ count greater than 200/mm3 and an HIV RNA load greater than 20,000 copies/mL (OR = 5.78; 95% CI = 4.17-8.08) and women with a CD4+ count greater than 200/mm3 and an HIV RNA load less than 20,000 copies/mL (OR = 3.12; 95% CI = 2.36-4.12), after adjustment for other factors. Other risk factors among HIV-positive women included racial/ethnic background (African-American versus Caucasian, OR = 1.64; 95% CI = 1.19-2.28), current smoking (yes versus no; OR = 1.55; 95% CI = 1.20-1.99), and younger age (age < 30 years versus > or = 40 years; OR = 1.75; 95% CI = 1.23-2.49).

CONCLUSIONS

Although the strongest risk factors of HPV infection among HIV-positive women were indicators of more advanced HIV-related disease, other factors commonly found in studies of HIV-negative women, including racial/ethnic background, current smoking, and age, were important in HIV-positive women as well.

Epidemiology of genital human papillomavirus

Genital human papillomavirus (HPV) infection is the most common sexually transmitted viral infection and the major risk factor for cervical neoplasia worldwide; however, little is still known about the epidemiology and natural history of the disease. Prospective cohort studies currently being conducted will increase our knowledge and understanding of these issues and provide critical information for the formulation of future primary and secondary prevention strategies.

HPV 16 antibody prevalence in Jamaica and the United States reflects differences in cervical cancer rates

Human papillomavirus (HPV) is widely accepted as the primary etiologic agent in the development of cervical cancer. DNA of a particular HPV type, HPV 16, is found in about half of tumors tested. Inconsistent with this causal relationship, however, population-based studies of HPV DNA prevalence have often failed to find high rates of anogenital HPV infection in countries with high cervical cancer rates. To examine this issue, we used serology to compare HPV 16 exposure in healthy volunteer blood donors in the United States (n = 278) and similar subjects from a country with 3-fold higher cervical cancer rates, Jamaica (n = 257). Jamaican sexually transmitted disease (STD) patients (n = 831) were also studied to examine in detail the relation of HPV 16 antibodies with sexual history. Serology was conducted using an ELISA employing HPV 16 virus-like particles (VLPs). Age-adjusted seroprevalence rates were greatest among male (29%) and female (42%) STD patients, intermediate in male (19%) and female (24%) Jamaican blood donors and lowest among male (3%) and female (12%) U.S. blood donors. The higher seroprevalence in women was significant, and prevalence tended to increase with age. In multivariate logistic regression, controlling for age and gender, Jamaican blood donors were 4.2-fold (95% CI 2.4-7.2) and STD patients 8.1-fold (95% CI 5.0-13.2) more likely to have HPV 16 VLP antibodies than U.S. blood donors. Among STD patients, HPV 16 antibodies were associated with lifetime number of sex partners and years of sexual activity, as well as other factors. Our data suggest that HPV 16 VLP antibodies are strongly associated with sexual behavior. Moreover, exposure to HPV 16 appears to be much greater in Jamaica than in the United States, consistent with the high rate of cervical cancer in Jamaica.

High risk genital papillomavirus infections are not spread vertically

The Medline-indexed literature on risk factors for HPV infection and HPV transmission is critically reviewed. Principles for assay validation and interpretation, reliability of different study designs and principles for interpretation of conflicting reports are discussed. The conclusions arrived at can be summarised as: (1) There is overwhelming epidemiological evidence that the only quantitatively important mode of transmission of infection with oncogenic genital HPV types is sexual. (2) There is also evidence that benign genital HPV types can be transmitted sexually, but the epidemiological data on the benign virus types are less extensive and less clear. (3) Perinatal HPV transmission is unequivocally demonstrated only for the rare disease juvenile respiratory papillomatosis.

Development of a multi-item scale to quantitatively assess sexual behaviors and the transmission of high- and low-risk human papillomaviruses

BACKGROUND

Epidemiologic research is frequently hindered by the inherent difficulty in quantifying the risk of sexually transmitted disease (STD) acquisition associated with individual patterns of sexual behavior.

GOAL OF THE STUDY

To develop a quantitative sexual behavior risk scale and demonstrate its predictive validity in an assessment of risk factors for incident infection with human papillomaviruses (HPVs).

STUDY DESIGN

Data from a prospective study of HPV infection in female university students was used to generate quantitative multi-item sexual behavior scales which were used in Cox regression analyses.

RESULTS

Although risk was incurred both in casual sexual encounters and in noncasual relationships, risk in these contexts were only weakly correlated. The construction of separate measurement scales was performed.

CONCLUSIONS

Improved precision of measurement of STD risk demonstrated that significant risk was associated with different patterns of sexual behavior and was incurred in both casual and/or noncasual relationships. Scores on the sexual behavior risk scales were highly predictive of incident infection with HPV types of both high and low oncogenic potential.

Risk factors for incident and recurrent condylomata acuminata among women. A population-based study

BACKGROUND

Condylomata acuminata is one of the most common sexually transmitted diseases (STDs) diagnosed in the United States, yet relatively little research has been conducted on the determinants of this disease in well-defined populations.

GOAL

To determine the exposures that predispose a woman to the development of condylomata acuminata or genital warts.

STUDY DESIGN

A population-based case-control study was conducted among enrollees of Group Health Cooperative of Puget Sound. Patients (94 women with incident and 55 women with recurrent condyloma) were diagnosed between April 1, 1987 and September 30, 1991. Control subjects were 133 women without a history of genital warts. An in-person interview was conducted to collect information on subject characteristics, exposures, and on all episodes of genital warts.

RESULTS

Women with five or more partners within the 5 years before reference date were over seven times more likely to have incident condyloma (relative risk [RR], 7.5; 95% confidence interval [CI], 3.1-18.1) and over 12 times more likely to have recurrent condyloma (RR, 12.8; 95% CI, 4.2-38.9) compared with women with only one sexual partner during this time period. An increased risk of incident condyloma was also associated with a history of any STD (RR, 2.6; 95% CI, 1.1-5.8), a history of oral herpes (RR, 2.2; 95% CI, 1.1-4.4), and a history of allergies (RR, 2.0 95% CI, 1.0-3.8). Our data did not support a strong association between risk of condyloma and smoking or recent use of oral contraceptives.

CONCLUSION

Our results suggest that risk of condyloma is primarily related to sexual behavior. We did not observe a strong association between risk of condyloma and many of the exposures considered to be potential cofactors for anogenital cancers associated with other types of human papillomaviruses.

Risk factors for HPV detection in archival Pap smears. A population-based study from Greenland and Denmark

The most important risk factor for cervical cancer is genital infection with certain types of human papillomavirus (HPV). The presence of HPV was studied in archival smears from a random sample of women living in Greenland (GW) and Denmark (DW) having, respectively, a high risk and an intermediate risk for cervical cancer. Risk factors were also examined of the original 126 Danish and 129 Greenlandic archived smears collected during October and November 1988. 125 were located from each country including all abnormal smears. HPV DNA was isolated from the smears and detected by means of a consensus polymerase chain reaction (PCR) detecting a broad spectrum of genital HPV types. HPV was detected in all the abnormal smears and in 22 and 33% respectively of the cytological normal smears from DW and GW. Risk of HPV was significantly higher in smears from women who started sexual life relatively recently (respectively, < or = 4 and < or = 6 years ago in DW and GW) compared with > or = 10 years ago (adjusted prevalence-OR: 9.3; 95% CI: 2.2-39.2 in DW and 5.9; 95% CI: 1.4-25.3 in GW). Among other important risk factors were age in both areas, lifetime number of sex partners and current smoking in DW and ever and gonorrhoea in GW. This study confirms the usefulness of the method as all abnormal smears were positive and, furthermore, the predictors for HPV presence in the normal smears corroborate with those found in recent studies of HPV in fresh cervical swabs. Thus, this method can be useful for large-scale epidemiological studies of HPV DNA in already sampled material.

Managing sexually transmitted diseases in adolescents

Control of sexually transmitted diseases (STDs) in adolescents is a primary responsibility of health care providers. Using the tools of history and physical examination, and drawing on the awareness of different stages of adolescent development, health care providers can define at-risk for STDs. This article discusses screening practices, disease control through reporting and preventive counseling, and treatment guidelines for common STD syndromes.

Clinical update on the role of HPV and cervical cancer

In the mid-1980s, a clear connection was made between infection by the human papillomavirus (HPV) and cervical cancer. This association led to the generation of a large body of literature about the diagnosis, testing, treatment, transmission and, virological life span of HPV-related neoplasms and cancers. Because of advances in virology, molecular biology, and biochemistry, more is known about HPV and its effects on cervical neoplasms than ever before. Because deaths from cervical cancer, while less common in the United States and western Europe, account for 20% of cancer deaths in women worldwide (1), accurate knowledge of the disease and its prevention is critical for nurses working with patients both with preinvasive and invasive disease.

Risk factors for HPV infection in women from sexually transmitted disease clinics: comparison between two areas with different cervical cancer incidence

We have compared risk factors for human papillomavirus (HPV) infection in very sexually active women [attenders of clinics for sexually transmitted diseases (STDs)] living in 2 areas with a 4-fold difference in cervical cancer incidence, i.e., Greenland and Denmark. The results were compared with findings of HPV infection in men attending the STD clinics during the same period. Overall, 204 Greenlandic women (GW), 187 Danish women (DW), 103 Greenlandic men and 216 Danish men were included. A similar age distribution was found in the 2 female populations. The GW reported significantly more sexual partners, earlier first intercourse and more STDs, but HPV was less frequently detected in the GW (25%) than in the DW (35%). However, this could be explained by a difference in the age pattern of HPV prevalence seen in the 2 areas. In each geographical area, the age pattern of HPV prevalence in men was very similar to that seen in women. The most important risk factors for HPV detection were the same in both female populations, i.e., age, years since first sexual intercourse and number of partners in the last years. In conclusion, the pattern of risk factors for HPV infection was the same in STD women from a high-risk area and a low-risk area for cervical cancer. Our results also show that the use of an overall HPV prevalence for comparing populations is meaningless, even in populations with similar age distribution.

A case-control study of human papillomavirus and cervical squamous intraepithelial lesions (SIL) in Harris County, Texas: differences among racial/ethnic groups

We conducted a case-control study of the association between SIL and HPV among whites (W), African Americans (AA), and Hispanics (H) in Harris County, Texas. Cases were identified at M.D. Anderson Cancer Center Colposcopy Clinic. Controls were identified among women obtaining routine Pap screening at two Harris County Health Department Clinics. HPV was detected by a PCR-based fluorescent assay. Dichotomous and polytomous logistic regression models were used to estimate adjusted odd ratios (AOR) and 95% confidence intervals (CI) for SIL among racial/ethnic groups and grade of disease. Prevalence of HPV infection was 64% in low grade SIL (LSIL), 84% in high grade SIL (HSIL), and 19% in controls. Risk of SIL was higher in H than in W and AA, AOR 29.5 (12.4-70.5), 15.3 (6.0-33.8), and 5.8 (2.6-12.6), respectively. Similarly, racial/ethnic differences were observed for both LSIL (AOR = 16.6, 7.7, and 4.3, respectively) and HSIL (AOR = 78.6, 34.6, and 14.2, respectively). Findings support the association between SIL and HPV and differences in the strength of the association with LSILs and HSILs. Data also suggest a higher risk for H and a lower risk for AA.

The pediatrician and the sexually active adolescent. A primer for sexually transmitted diseases

Sexual activity is a common practice among young adolescents, placing them at high risk for STDs, many of which have long-term consequences. Early diagnosis and treatment are essential to limit both the consequences and the spread of these infections. The clinician has a responsibility to the adolescent patient to recognize and treat these diseases. Using history and physical examination, the clinician should be able to determine an adolescent's risk for an STD, and, based on this risk, undertake the appropriate evaluations. Patient treatment, follow-up, and management of sex partners are then guided by the results of either presumptive or definitive diagnostic tests.

PCR detection of human papillomavirus: comparison between MY09/MY11 and GP5+/GP6+ primer systems

Human papillomavirus (HPV) is an etiologic agent of cervical cancer and is the most common sexually transmitted disease in women. PCR amplification of HPV genomes is the most sensitive method for the detection of cervicovaginal HPV. We have compared the two most commonly used PCR primer sets, MY09/MY11 (MY-PCR) and GP5+/GP6+ (GP+-PCR), for the detection of HPV DNA in cervicovaginal lavage samples from 208 women. Oligonucleotide probes for 39 different HPV types were used. Both primer sets amplified a wide spectrum of HPV genotypes and detected similar overall prevalences of 45% (94 of 208) and 43% (89 of 208), respectively. The MY-PCR system detected 27 of 30 (90%) samples with multiple HPV types, whereas the GP+-PCR system detected 14 of 30 (47%) samples with multiple HPV types. Differences in the detection of HPV types 35, 53, and 61 were noted between the two primer systems. Serial dilution of plasmid templates indicated a 3-log decrease in the amplification of HPV type 35 by MY-PCR and HPV types 53 and 61 by GP+-PCR. These results indicate that although the MY-PCR and GP+-PCR identified nearly equivalent prevalences of HPV in a set of clinical samples, differences in the detection of specific types and infections with multiple types were found. Differences in the sensitivities and characteristics of the PCR systems for the detection of HPV within clinical samples should be considered when comparing data between studies and/or in designing new studies or clinical trials.

Seropositivity against HPV 16 capsids: a better marker of past sexual behaviour than presence of HPV DNA

OBJECTIVES

To assess if seropositivity to human papillomavirus type 16 capsids is a better marker of sexual history than the presence of HPV DNA.

STUDY DESIGN

A population based age stratified random sample of 234 Norwegian women (mean age 32.8 years, range 20-44) was examined for HPV serum antibodies, cervical HPV DNA, cytology and age in relation to sexual behaviour.

RESULTS

Neither age nor age at first sexual intercourse was associated with HPV 16 antibodies. Adjusted ORs for 4-5; 6-10 and > 10 versus 0-1 lifetime sexual partners, were 13.1 (95% CI 1.5-110.8), 8.2 (1.0-69.6) and 10.5 (1.2-94.0) for HPV 16 seropositivity, respectively; and 2.6 (0.2-27.8), 3.4 (0.4-31.7) and 4.1 (0.4-42.8) for HPV 16 DNA positivity, respectively.

CONCLUSION

Seropositivity to HPV 16 capsids is positively associated with the number of sexual partners, suggesting that HPV 16 is predominantly sexually transmitted. The fact that serology had a stronger association with number of sexual partners than viral DNA suggests that seroreactivity is a better measure of lifetime history of HPV infection.

Human papillomavirus type 16 sequence variants: identification by E6 and L1 lineage-specific hybridization

A catalog of human papillomavirus (HPV) type 16 (HPV-16) E6 and L1 signature nucleotides was used to develop PCR-based oligonucleotide probe systems capable of distinguishing HPV-16 class and subclass variants. Twenty-three E6-specific oligonucleotide probes targeting 13 variant nucleotide positions and 12 L1-specific oligonucleotide probes targeting 6 variant nucleotide positions were used to characterize HPV-16-containing cervicovaginal lavage specimens. Nucleotide positions that could be distinguished included E6 nucleotides 109, 131, 132, 143, 145, 178, 183, 286, 289, 335, 350, 403, and 532 and L1 nucleotides 6695, 6721, 6803, 6854, 6862, and 6994. Combined hybridization patterns were assigned on the basis of the predicted HPV-16 class, subclass, or minor class variants described previously (T. Yamada, C. M. Wheeler, A. L. Halpern, A.-C. M. Stewart, A. Hildesheim, and S.A. Jenison, J. Virol. 69:7743-7753, 1995). The major HPV-16 variant lineages detected included European prototype-like (E-P), Asian (As), Asian-American (AA), and African (Af1 and Af2) lineages. In addition, E-G131, an E-class variant, and AA-G183, an AA-class variant, were also identified. For each clinical specimen, DNA hybridization results were compared to nucleotide sequence determinations. Targeted L1 and E6 marker nucleotides covaried within all HPV-16 variant isolates examined. These hybridization-based methods result in minimal misclassification error, are amenable to targeting additional lineage-specific nucleotide positions, and should facilitate the large-scale, low-cost analysis of HPV-16 variants in epidemiologic investigations. Specifically, these methods will facilitate epidemiologic studies of HPV-16 transmission and natural history, as well as studies of associations between HPV variants, host immune responses, and cervical neoplasia.

Human papillomaviruses and cervical cancer

Molecular and epidemiological studies conducted over the last 20 years led to the recognition of certain types of human papillomavirus (HPV) as the etiological agents of cervical cancer, a very common neoplasia, particularly in developing countries. More than 70 HPVs have been described, including both cutaneous and mucosal types. About half of the known HPVs, and an even higher number of variants, have been isolated from genital mucosas. The association of certain types primarily with normal tissues and benign lesions, as opposed to cancer-associated types, has led to the concept of low and high oncogenic risk HPVs, respectively. The latter express oncogenic proteins that interfere with cell growth control functions. As a consequence of the continuous expression of these viral genomes, chromosome instability may occur, leading to fully transformed cells. Studies indicate that persistence of high-risk HPVs may determine progression to more severe stages of cervical disease, while the majority of HPV infections are transient and do not seem to be important in cervical carcinogenesis. The risk for disease progression seems also to be associated with viral burden. Prospective epidemiological studies will contribute to the knowledge of the natural history of HPV infections and provide information on the determinants of viral persistence. Data derived from these studies may define the clinical utility of HPV testing and its use in cervical cancer prevention programs.

Socioeconomic differences in cervical cancer: two case-control studies in Colombia and Spain

OBJECTIVES

This study examined the causes of socioeconomic differences in invasive cervical cancer in two countries that differ substantially in cervical cancer incidence and economic development.

METHODS

Data were derived from two case-control studies carried out in Spain and Colombia; there were 373 case subjects, 387 control subjects, and 425 husbands interviewed with a structured questionnaire. Exfoliated cells were obtained from cervical or penile scrapes and tested for human papillomavirus (HPV) DNA.

RESULTS

Relative to better educated women, women with low educational levels in both countries reported fewer Pap smears and had a higher prevalence of HPV DNA. The prevalence ratio of HPV DNA across educational strata was twofold in Spain and fourfold in Colombia. In both countries, husbands of poorly educated women reported higher use of prostitutes than husbands of better educated women. In Colombia, 30% of husbands of poorly educated women harbored HPV DNA, compared with 10% of husbands of better educated women.

CONCLUSIONS

Socioeconomic differences in invasive cervical cancer could be partly explained by differences in the prevalence of HPV DNA and by a lower use of preventive care.

Risk factors for HPV DNA detection in middle-aged women

BACKGROUND AND OBJECTIVES

Strong epidemiologic evidence indicates that human papillomavirus (HPV) is the main etiologic factor of cervical cancer. A few cohort studies suggest that most HPV infections are transient in young women and that persistent HPV infections are more common in older women. Little is known about the determinants of persistent HPV infections. The present study was aimed at increasing our knowledge about these determinants.

GOALS

To identify risk factors for genital HPV DNA detection among cytologically normal middle-aged women.

STUDY DESIGN

Eight hundred ten women who participated as control subjects in three case-control studies on cervical cancer in Spain, Colombia, and Brazil were included in this study. After an interview, women underwent a gynecologic examination with collection of exfoliated cells for a Papanicolaou smear and HPV DNA detection. Human papilloma virus DNA was detected by polymerase chain reaction (PCR)-based hybridization techniques.

RESULTS

The HPV positivity rate was 10.5% in the whole population, but was higher in the areas with high incidence of cervical cancer (17% in Brazil and 13% in Colombia) than in Spain (4.9%), which is a low-risk area for cervical cancer. Age was related to the prevalence of HPV DNA in Brazil, but not in Spain and Colombia. In univariate analyses in all three countries, the prevalence of HPV DNA was positively associated with the number of lifetime sexual partners and inversely associated with the levels of family income and with age at first sexual intercourse. There was four times increase in the odds ratio (OR) of HPV infection in women who had six or more lifetime sexual partners compared with those with one or less. The use of any kind of contraceptive tended to decrease the OR for HPV detection. Their ORs ranged from 0.44 (barrier methods) to 0.48 (oral contraceptives). In Spain and Colombia, antibodies against Chlamydia trachomatis were positively associated with the prevalence of HPV DNA. In a final multivariate model, the positive associations with lifetime number of sexual partners, socioeconomic status, and C. trachomatis persisted.

CONCLUSIONS

These results support the sexual transmission of HPV and suggest that socioeconomic status and antibodies to C. trachomatis are independent predictors of HPV detection in middle-aged cytologically normal women.

Is oral contraceptive associated with genital warts?

OBJECTIVE

To measure the association between oral contraceptive use and the prevalence of genital warts in women.

METHODS

Cross sectional case control study comparing oral contraceptive use in women with and without genital warts attending a city centre genitourinary medicine clinic controlling for recent sexual activity, the presence of other sexually transmitted infections, socio-economic class and history of pregnancy using a multivariate logistic regression model.

RESULTS

After controlling for potential confounding variables women with genital warts were significantly more likely to be current users of the oral contraceptive pill (OR 1.7, 95% CI 1.3-2.2).

CONCLUSION

The study suggests that women taking the oral contraceptive may be at increased risk of presenting with genital warts. Previously published papers provide some support for this hypothesis and potential biological mechanisms are discussed.

Risk factors associated with genital HPV infection

The genital human papillomavirus (HPV) is directly associated with cervical cancer, the second most common form of cancer among women. The study was guided by a synergistic interaction model of HPV risk factors. The relative risk of selected risk factors and cofactors associated with genital HPV infections was identified. Women at highest risk for acquiring an HPV infection had (a) initiated sex before age 15, (b) more than four lifetime sex partners, (c) more than one "once only" sexual partner, and (d) chosen male sex partners who previously had > 16 other female sex partners. Cofactors that increased risk by possibly contributing to progression of genital HPV infection were initiating oral contraceptive use before age 15 and having acquired more than three other sexually transmitted diseases. Past and current smokers were at a slightly higher risk compared to nonsmokers. Although other studies have identified risk factors, few have identified the relative risk of these factors.

Pregnancy and cervical infection with human papillomaviruses

OBJECTIVE

This investigation was undertaken to assess whether pregnancy represents a risk factor for human papillomavirus (HPV) infection which is independent of age and other known HPV risk factors.

METHODS

One hundred eighty-nine women were enrolled from the outpatient clinics of a large municipal hospital. The subjects completed a self-administered questionnaire and underwent a gynecological examination which included a cervicovaginal lavage. Lavage samples were assessed for the presence of HPV DNA by restriction enzyme analysis and Southern blot hybridization. Statistical significance was assessed by the chi 2-test. Logistic regression was used to assess the association between pregnancy and HPV while controlling for the effect of other risk factors.

RESULTS

The prevalence odds ratio (POR) for the association of pregnancy and HPV infection was 2.2 (95% C.I. 1.1-4.5). The prevalence of HPV increased with increasing gestational age (HPV prevalence of 18.9% among non-pregnant women vs. 27.3% in those in the first 12 weeks of pregnancy and 39.7% in those who were past the 12th week of pregnancy). Although statistical significance was not achieved in a multivariate model which controlled for age, race/ethnicity, education, age at first coitus, number of sexual partners within the last year and parity, the POR associated with the current pregnancy (POR = 2.1) was not substantially changed by correcting for these risk factors, suggesting that these factors were not significant confounders of the association between pregnancy and HPV infection.

CONCLUSION

Current pregnancy is associated with a modestly increased prevalence of cervical HPV infection. This association appears to be independent of age and other major HPV risk factors.

Declining prevalence of cervicovaginal human papillomavirus infection with age is independent of other risk factors

BACKGROUND AND OBJECTIVES

Human papillomavirus (HPV) infection of the female genital tract is the most common sexually transmitted disease. Although the prevalence of HPV in women without detectable cervical disease has been shown to decline with increasing age, the relationship to sexual behavior has not been investigated.

GOAL

To identify risk factors for, and associated with the age-dependent decline in, genital HPV infection in women.

STUDY DESIGN

The prevalence of HPV was determined in a cohort of 439 sexually active inner-city women between the ages of 18 and 50 years recruited in Brooklyn, New York. Cervicovaginal cells were collected by lavage, and HPV was detected by low-stringent Southern blot hybridization.

RESULTS

The prevalence of HPV infection ranged from 36% in women younger than 25 years of age to 2.8% in women 45 years or older. Logistic regression analysis identified an increased risk for cervical HPV infection to be independently associated with number of sex partners in the past year (odds ratio [OR], 1.04 per yearly increase in age; 95% confidence interval [CI], 1.00 to 1.08), younger age (OR, 0.92 per year increase in age; 95% CI, 0.88 to 0.95), and not living with partner (OR, 2.28; 95% CI, 1.40 to 4.22).

CONCLUSIONS

The lower prevalence of HPV infection in older women compared to younger women was found to be independent of sexual behavior. These results suggest that a biologic effect, such as HPV immunity acquired over time and with multiple exposures, may mediate the inverse relationship between age and HPV prevalence.

Comparison of development of serum antibodies to HPV16 and HPV33 and acquisition of cervical HPV DNA among sexually experienced and virginal young girls. A longitudinal cohort study

OBJECTIVES

To study the importance of sexual activity and early coitus debut on the risk for acquiring infection with human papillomavirus (HPV) type 16 or 33.

STUDY DESIGN

Ninety-eight healthy adolescent girls were followed up with consecutive interviews and donations of serum and cervical brush samples during 2 years.

RESULTS

Fourteen percent of sexually experienced girls had serum immunoglobulin G to HPV16 and/or HPV33 capsids, and 14% also had cervical HPV16 or HPV33 DNA. Seropositivity for HPV correlated with detection of cervical HPV DNA. None of the 36 girls without coital experience was seropositive or harbored cervical HPV DNA. Seropositivity for HPV was correlated strongly with the number of sexual partners: Odds ratio for > 1 sexual partner was 16.3 (P < 0.001), and for early coitus debut (younger than 17 years of age), it was 14.3 (P < 0.002).

CONCLUSIONS

Both HPV serology and HPV DNA testing indicated that the number of sexual partners and earliness of coitus debut determined the risk for acquiring HPV infection and that nonsexually transmitted infections are rare or nonexistent among adolescent girls.

The epidemiology of cervical carcinogenesis

Epidemiologic and laboratory data suggest that cervical cancer typically arises from a series of causal steps. Each step can be studied separately in the hope of better etiologic understanding and improved cancer prevention. The earliest identified etiologic step is infection of young women with specific types of venereally transmissible human papillomaviruses (HPVs). Cervical HPV infections often lead to low grade squamous intraepithelial lesions (mildly abnormal Pap smears). Human papillomavirus infections and their associated lesions are extremely common among young, sexually active women. The infections typically resolve spontaneously even at the molecular level within months to a few years. Uncommonly, HPV infections and/or low grade lesions persist and progress to high grade lesions. The risk factors for progression are mainly unknown but include HPV type and intensity, cell-mediated immunity, and reproductive factors. Nutritional factors or co-infection with other pathogens may also be involved at this apparently critical etiologic step between common low grade and uncommon high grade intraepithelial lesions. Except for advancing age, no epidemiologic risk factors have been found for the next step between high grade intraepithelial lesions and invasive cancer. At the molecular level, invasion is associated with integration of viral DNA. Based on worldwide research, the steps in cervical carcinogenesis appear to be fundamentally the same everywhere, with a central role for HPV infection. The importance of etiologic cofactors like smoking, however, may vary by region.

Human papillomavirus and cervical neoplasia: a case-control study in Taiwan

As part of a large-scale, community-based cervical neoplasia screening project in rural Taiwan, a case-control study was undertaken to evaluate the etiologic role of human papillomavirus (HPV) infection in this mainly monogamous (2% reported having multiple sexual partners) female population. A total of 88 biopsy-confirmed cases and 261 cytologically normal controls were selected for the study. The case group included 40 cases of cervical intraepithelial neoplasia (CIN) 1, 9 of CIN 2, 36 of CIN 3 and 3 cases of invasive cancer. Cervical swabs collected at screening from study subjects were tested for HPV DNA by an LI consensus primer polymerase chain reaction (PCR)-based technique. HPV DNA was found in 92% of high-grade cases (CIN 2-3 and invasive cancer); 54% of low-grade cases (CIN 1); and 9% of controls. HPV was significantly associated with both high-grade and low-grade cervical neoplasia. As reported in Western countries, HPV 16 was the predominant type among HPV-positive high-grade cases. However, HPVs 52 and/or 58 combined were the most common types among HPV-positive low-grade cases and controls. Among women without any high-risk HPV infection (types 16, 18, 31 or 45), those with multiple-type HPV infection had a higher risk for high-grade cervical neoplasia than those with single-type infection. Overall, 91% of high-grade cases and 50% of low-grade cases could be attributed to HPV infection. Our results show that, even in this monogamous population, HPV is the major risk factor for high-grade cervical neoplasia.

Association of human papillomavirus with malignant and premalignant lesions of the uterine endometrium

The possible association of human papillomavirus (HPV) with endometrial hyperplasia and endometrial adenocarcinoma was investigated. DNA from frozen tissues of 30 endometrioid carcinomas of Japanese patients was tested for HPV DNA by Southern blot hybridization analysis. Screening with HPV type 58 probe under low stringency conditions showed the presence of HPV DNA in two of 30 endometrioid carcinomas. High stringency hybridization identified HPV type 16 in the two positive specimens. The presence of HPV was further analyzed by polymerase chain reaction (PCR)-Southern blot analysis of DNA from archival tissue blocks of the initial 30 endometrioid carcinomas as well as an additional 17 endometrioid carcinomas and 13 atypical hyperplasias of the endometrium from Japan and 38 endometrioid carcinomas from the United States. Polymerase chain reaction amplification using type 16-specific HPV primers for a portion of the E6 open reading frame was positive in six of 47 (13%) endometrioid carcinomas from Japan, including two in which HPV 16 was not detected by Southern blot analysis and two of 38 (5%) endometrioid carcinomas from the United States. Polymerase chain reaction amplification using L1 consensus sequence primers was positive for HPV in two of 13 (15%) endometrial hyperplasias, 13 of 47 (28%) endometrioid carcinomas from Japan, and six of 38 (16%) endometrioid carcinomas from the United States. Slot blot hybridization identified HPV type 16 in seven of the L1 PCR products, including all but one specimen testing positive for HPV type, 16 using E6 type specific primers. In situ hybridization was positive for HPVs 16/18 in glandular epithelial tumor cells in six of the PCR-positive specimens. An additional specimen showed staining for HPVs 16/18 in acellular luminal debris in association with squamous metaplasia of the tumor, but staining was negative in the glandular cells of the tumor. Human papillomavirus was not detected by in situ hybridization in the remaining specimen, which was PCR positive for HPV 16. In situ hybridization was weakly positive for HPVs 31/33/35 in one specimen and was weakly positive for HPVs 6/11 in benign endometrial epithelial cells but not in tumor cells of another specimen that tested positive for HPV by L1 PCR. Two dimensional gel electrophoresis performed on two specimens showed that HPV DNAs were integrated into cellular DNA with no episomal coexistence. These findings suggest that HPV, especially HPV 16, may play an etiologic role in a fraction of endometrioid adenocarcinomas.

A cohort study comparing the detection of HPV DNA from women who stop and continue to smoke

The objective of this study was to compare the detection of human papillomavirus (HPV) DNA in women who stopped smoking, and those who continued to smoke. Women entering a smoking cessation programme had tampon specimens collected and analyzed for HPV DNA using polymerase chain reaction (PCR) (L1 consensus primers). Women with HPV DNA in their initial specimens had follow-up specimens collected 1 year later. The stored initial specimens were reanalyzed in the same experiment with the follow-up specimen. In addition, Hybrid Capture and quantitative PCR were used to determine if the change in HPV DNA over the year of follow-up was greater in either group. Of 197 women who were recruited into the study, 57 (29%) were positive for HPV DNA. Second specimens were obtained from 49 of these 57 women. Of these 49 women, 13 had stopped smoking and 36 continued to smoke. The detection of HPV DNA in follow-up specimens was not significantly different in the women who stopped smoking (54%) compared to those who continued to smoke (50%, p = 0.81). Furthermore, the change in the amount of HPV DNA during follow-up was not different in women who stopped smoking compared to women who continued to smoke (p > 0.25). This study suggests that smoking cessation does not affect the detection of genital HPV DNA. On the basis of these findings it is likely that smoking does not increase the risk of invasive cervical cancer by prolonging the detection of HPV DNA.

Accuracy and interlaboratory reliability of human papillomavirus DNA testing by hybrid capture

Epidemiologists and clinicians wishing to introduce human papillomavirus (HPV) testing into cervical cancer prevention programs need standardized, reliable, and accurate HPV DNA tests that can detect the full spectrum of pathogenic HPV types. The Hybrid Capture System assay from Digene (hybrid capture assay) is a nonradioactive kit designed to detect 14 HPV types in two groups: a mix of 9 high-risk types associated with anogenital cancer (HPV types 16, 18, 31, 33, 35, 45, 51, 52, and 56) and another group of 5 low-risk types associated with condyloma acuminatum (HPV types 6, 11, 42, 43, and 44). The assay yields quantitative data meant to reflect viral concentration. In a study of 199 cervical specimens from women with concurrent Pap smears, we assessed the reliability of the new assay by comparing the hybrid capture assay results from three laboratories. We assessed the accuracy of the hybrid capture assay in comparison with a reference standard of HPV DNA content (multiple testing by several methods in two reference laboratories). We also compared the hybrid capture assay results with the concurrent cytologic diagnoses on the basis of an independent review of each smear by five pathologists. Pairwise interlaboratory agreement rates on HPV positivity for either high-risk or low-risk types ranged from 87 to 94%, and kappa values ranged from 0.61 to 0.83. Among specimens positive for high-risk types (the most important clinical outcome), the interlaboratory correlations of the quantitative data ranged from 0.60 to 0.90. Test results from all three laboratories were strongly associated with those of the HPV DNA reference standard and with the concurrent cytopathologic diagnoses. The most common errors were sporadic, apparently false-positive results.

Interval between menarche and first sexual intercourse, related to risk of human papillomavirus infection

The purpose of this investigation was to study the occurrence of human papillomavirus (HPV) infection in relation to the interval between menarche and first intercourse. Two hundred eight subjects, aged 13 to 21 years, were recruited from an ambulatory adolescent clinic. Patients were excluded if they had a history of genital warts or an abnormal Papanicolaou smear. All subjects completed a self-administered questionnaire regarding demographics and their menstrual, sexual, and contraceptive histories. HPV infection was determined by in situ hybridization or changes consistent with HPV on a Papanicolaou smear, or both. The prevalence of HPV infection was 19.2%. The average interval between menarche and onset of sexual activity was 26.6 months for those who were found to have HPV infection compared with 35.7 months for those whose test results were negative (p = 0.02). First sexual intercourse within 18 months of menarche was associated with a significant elevation of risk of HPV infection, in comparison with that in adolescents who postpone first intercourse 3 to 4 years after menarche. These data suggest that factors such as increased biologic vulnerability may play a role in HPV infections among adolescent women.