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Logo of nihpaAbout Author manuscriptsSubmit a manuscriptNIH Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
Tipica. Author manuscript; available in PMC Dec 1, 2010.
Published in final edited form as:
Tipica. Jun 1, 2009; 5(1): 32–38.
PMCID: PMC2995251
NIHMSID: NIHMS170665

Knowledge and Risk Perception Regarding HPV Among Latino Alternative School Students in Houston, Texas

Abstract

Human Papillomavirus (HPV) is the most common STI among youth in the U.S. As alternative school students are at higher risk of acquiring STIs compared to regular high school students, this study examined HPV knowledge and risk perception among Latino youth attending 9 alternative high schools in Houston, Texas. HPV knowledge measures assessed prevalence, health consequences, symptoms, transmission, and risk reduction strategies. Three measures assessed perceived risk. The sample included 414 youth (58.4% female) with a mean age of 16.6 years (SD = 1.86); 63.8% were sexually experienced. Most (76.0%) were U.S.-born to parents from Mexico, Central or South America (70.8% of mothers and 77.8% of fathers, respectively); 61.7% had parents with less than a high school education. Results indicate that youth answered 1 out of 5 HPV knowledge items correctly (mean = 1.3, SD = 1.45); 35.8% identified skin-to-skin contact during sex as the most common mode of HPV transmission, and 72.5% selected condoms as an effective HPV risk reduction strategy followed by avoiding multiple partners (55.8%), abstinence (47.5%), monogamous relationships (26.8%) and HPV vaccination (22.3%). Only twenty-seven youth (6.5%) perceived themselves to be at high risk for contracting HPV. Regression analyses examining the association between demographic variables, sexual behavior, HPV knowledge, and HPV risk perception, showed significant associations for mothers’ place of birth only – youth whose mothers were born outside of the U.S. had significantly lower HPV knowledge than those with American-born mothers (p < 0.007). Findings indicate the need for enhanced educational efforts among Latino alternative school youth regarding the prevalence of HPV and effective risk reduction strategies.

Keywords: Alternative schools, Latino, at-risk youth, HPV

Human Papillomavirus (HPV) is a virus group that includes over 100 different types, and approximately 40 types infect the anogenital region. HPV infection is the most common sexually transmitted infection (STI) in young sexually active populations in developed countries. Nine to 13 percent of the world population, or about 630 million, are estimated to be infected with HPV.(World Health Organization, 2001) In the U.S., approximately 20 million Americans are infected with HPV, almost half (9.2 million) of whom are adolescents and young adults aged 15–24 years.(Weinstock, H., Berman, S., & Cates, W., Jr., 2004; Centers for Disease Control and Prevention, 2004) In addition, an estimated 6.2 million new cases of HPV infection are diagnosed annually among the U.S. population aged 15–44 years, 75% of which occur among individuals 15-24 years of age.(Weinstock, H., Berman, S., & Cates, W., Jr., 2004; Centers for Disease Control and Prevention, 2004) Among female adolescents (aged 14-19) participating in the 2003-2004 National Health and Nutrition Examination Survey (NHANES) one in four (26%) had an STI, the most common being HPV (18.3%), followed by Chlamydia (3.9%), trichomoniasis (2.5%), and herpes simplex virus (HSV-2) (1.9%).(Centers for Disease Control and Prevention, 2008).

HPV presents a serious public health problem as certain types (predominantly HPVs 16 and 18) have been associated with cancer of the cervix, vulva, vagina, anus, penis, oral cavity, and oropharynx.(Bosch, F. X., Lorincz, A., Munoz, N., Meijer, C. J., & Shah, K. V., 2002; Parkin, D. M. & Bray, F., 2006) The economic burden of HPV infection is very high, and second only to the cost of HIV infection. In the U.S. population ages 15-24 years the estimated direct medical cost of HPV-related cervical abnormalities (in women), and external anogenital warts (in men and women) alone for the year 2000 was $2.9 billion ($3.0 billion for HIV), representing 45% of the total medical cost ($6.5 billion) of the eight most frequently reported STIs in this country.(Chesson, H. W., Blandford, J. M., Gift, T. L., Tao, G., & Irwin, K. L., 2004).

Latino youth in the U.S. are disproportionally at risk for sexually transmitted infections. According to the 2005 Youth Risk Behavior Surveillance Survey (YRBS), almost 47 percent of high school students in the U.S. (grades 9 to 12, approximately 14 to 18 years) has had sexual intercourse and the percentage is slightly higher among Latino students (51%).(Eaton, D. K. et al., 2006) Latino students were also more likely to have initiated sexual intercourse before age 13 compared to white students and were less likely to report condom use compared to black and white students.(Centers for Disease Control and Prevention, 2007c) These risky behaviors have contributed to higher rates of STIs among young Latinos in the United States.

Alternative high school students in the U.S. are at higher risk of acquiring STIs compared to students attending regular high schools.(Weller, N. F. et al., 1999; Grunbaum, J. A. et al., 2000) As of October 1, 2000, 612,900 students, or 1.3 percent of all public school students, were enrolled in public alternative schools or programs for at-risk students.(Kleiner, B. Porch R. and Farris E, 2002) Students are admitted to these alternative programs for a variety of reasons including poor academic performance, poor school attendance, disruptive behavior, substance use, pregnancy, and having contact with the juvenile justice system. The 1998 National Alternative High School YRBS found that 87.8% of students were sexually experienced, compared to 45.6% of students in regular high schools. Alternative school students were also more likely to have initiated sexual intercourse at an early age, less likely to report using condoms at last sexual intercourse, and almost twice as likely to report using alcohol or drugs at last sexual intercourse.(Grunbaum, J. A. et al., 2000; Kann, L. et al., 2000).

Given the advent of vaccines to reduce the risk of contracting HPV, it is important that health practitioners understand factors that may impede or facilitate vaccination uptake. According to the Health Belief Model, perceived risk for an infection is an important factor that may influence decisions regarding vaccination.(Becker, M. H., 1974) Knowledge regarding the prevalence, consequences, and transmission of an infection are also prerequisites for making informed decisions about vaccination.(Brewer, N. T. & Fazekas, K. I., 2007) A recent review of studies conducted in the U.S. regarding perceived risk for HPV and HPV knowledge and beliefs found that between 21% and 46% of youth perceived themselves to be at risk for HPV infection, and that knowledge of HPV, including prevalence and consequences, was modest overall.(Brewer, N. T. & Fazekas, K. I., 2007).

Methods

Study Sample

Youth were participants in the Safer Choices 2 study, a randomized controlled trial of an HIV, STI, and pregnancy prevention intervention conducted in nine alternative high schools in Houston, Texas.(Tortolero, S. R. et al., 2005) Schools were considered eligible to participate in the study if they: (a) served students at risk of not graduating (referred for academic or behavioral problems) and (b) were a stand-alone school (not a school within another school). The student population was predominantly low-income, inner-city, Latino and African American. Active parental and student consent were required for participation. The study received approval from the University of Texas Health Science Center at Houston Committee for the Protection for Human Subjects (HSC-SPH-99-056). Data were collected between August 2002 and March 2003 during follow-up data collection periods.

Procedure

Data were collected using an audio computer-assisted self-interview (ACASI) program. The use of computers for data collection has been found to be an effective and reliable method for obtaining confidential information such as sexual risk-taking behaviors.(Romer, D. et al., 1997; Gribble, J. N., Miller, H. G., Rogers, S. M., & Turner, C. F., 1999) Data collection was conducted in several locations depending on the youth’s in-school status. Youth who were still in school completed the interview during regular school hours in a quiet location (e.g., school library or empty classroom). Youth who were not in school, either because of graduation or chronic absenteeism, were interviewed in other community locations (e.g., public library or worksite) or at their home. Data collection staff provided a brief overview of how to use the computer and students completed practice items to become familiar with question and response formats.

The computers were equipped with headphones to maintain privacy and respondents were able to ask questions of the data collection staff, if needed. As each question appeared on the monitor, the student also heard the question through the headphones and received a prompt to select the appropriate response. Some hard-to-reach youth provided data via telephone interview with a trained data collector after multiple unsuccessful attempts to contact the youth in-person. All youth were informed that their participation was voluntary and that neither parents nor teachers would see their responses. To protect confidentiality, a unique identification number was assigned to each respondent. All interviews were conducted in English, as limited English proficiency was an exclusion criteria for the overall study.

Measures

Demographics

Several items assessed gender, age, Latino origin, youth’s place of birth, mothe r and father’s place of birth, and length of time living in the United States.

HPV knowledge

Three measures were used to address HPV knowledge. These were adapted from existing measures developed by Ramirez and colleagues.(Ramirez, J. E., Ramos, D. M., Clayton, L., Kanowitz, S., & Moscicki, A. B., 1997) The first measure included 5 items assessing knowledge of the consequences, symptoms, and prevalence of HPV. Example items were, “HPV (human papillomavirus) or genital warts can cause cancer of the cervix” and “Most of the time HPV (human papillomavirus) infection is without symptoms.” Response options included “true”, “false”, “not sure”, and “refuse to answer”. For analytical purposes, youth received one point for each correct answer, giving a scale score ranging from 0 to 5. The scale had acceptable reliability in this population (Cronbach’s alpha = 0.67). The second measure assessed HPV transmission knowledge. Youth were asked to select the one, most common mode of HPV transmission from ten response options including: skin-to-skin contact during vaginal or anal sex, oral sex, exchange of bodily fluids (blood, semen), kissing, sharing underwear or towels, shared drinking glasses, hot tubs, swimming pools, and toilet seats. The third measure assessed HPV risk reduction knowledge. Youth selected ways to reduce the risk of HPV infection from 9 response options including but not limited to: abstinence; monogamous sexual relationships; condom use; spermicides; HPV vaccine/shot; oral contraceptive pills (birth control pills), and eating a healthy diet.

HPV perceived risk

Three measures addressed HPV risk perception. The first measure assessed perceived chances of acquiring HPV, “What do you think are your chances of getting an HPV (human papillomavirus) infection? Response options ranged from “extremely high” to “extremely low”. An automated skip pattern classified youth responding “extremely high” or “somewhat high” as being at “high perceived risk”; all other responses were classified as being “low perceived risk.” The second measure assessed reasons why youth perceived their chances of infection as either high or low. Youth classified as “high perceived risk” were asked to select the reasons why they perceived their risk to be high, choosing from 8 options which included: have had sex; had unsafe sex (did not use a condom every time); had several sexual partners; tested positive for other STIs; and previous HPV history. Youth classified as “low perceived risk” selected the reasons why they perceived their risk to be low from eight options including: never had sex; always had safe sex (used a condom every time); had only one sexual partner; recently tested for negative for HPV, and was healthy with no symptoms. The third measure assessed the STIs about which youth were most concerned. Options included: herpes, HIV, hepatitis B, syphilis, gonorrhea, HPV, genital warts, Chlamydia and crabs.

Sexual behavior

Youth were asked whether they had ever had vaginal sex. Those who reported being sexually experienced received additional questions regarding sexual activity in the past three months, includin g number of sexual partners and number of times having sex without a condom.

Analyses for the current study were restricted to youth reporting Latino ethnicity. Descriptive analyses including Chi-square and Fisher’s Exact were used to examine the distribution of HPV knowledge and perceived risk among the total sample and stratified by gender. Bivariate linear and logistic regression analyses were conducted to examine the association between demographic variables and sexual behavior as the independent variables and HPV knowledge and risk perception as the dependent variables. Due to lack of significant associations at the bivariate level, no multivariate analyses were conducted.

Results

Data were collected from 414 Latino youth, including 337 in-person interviews and77 telephone interviews. Youth who completed the interview by telephone were significantly more likely to be female (p < 0.01), older (p < 0.001), and sexually experienced (p < 0.01) compared to those who completed an in-person interview. However, there were no significant differences in responses related to HPV based on mode of interview.

The sample was 58.4% female with a mean age of 16.6 years (SD = 1.86, range 13 to 23 years) (Table 1). The majority of youth had been born in the U.S. (76.0%) and was of Mexican heritage (79.1%). The mean length of time living in the U.S. was 13.6 years (SD = 3.63, range 0 to 20 years). Approximately three-quarters of youth reported that their mother or father was foreign-born (71.0% of mothers and 78.3% of fathers, respectively). Almost two-thirds of youth (61.7%) reported that their parents had less than a high school education.

Table 1
Demographic Characteristics of Latino Alternative High School Students(N=414)

Regarding sexual experience, 264 (63.8%) reported ever having had sex; of these, 192 (72.7%) reported being sexually active during the past three months. Among those who were currently sexually active, 44 (22.9%) had more than one sexual partner in the past three months and 127 (66.1%) had sex without a condom at least once in the past three months.

HPV knowledge

The overall mean score for knowledge regarding the consequences, symptoms, and prevalence of HPV was 1.3 (SD = 1.45). On average, youth answered 1 out of 5 items correctly. There was no significant difference in mean scores between males (M = 1.2, SD = 1.39) and females (M = 1.4, SD = 1.49) (p < 0.09). Regarding knowledge of HPV transmission, approximately one third (35.8%) correctly identified skin-to-skin contact during vaginal or anal sex as the most common mode of HPV transmission, whilst 39.5% responded “do not know”. Smaller percentages reported oral sex (12.6%), exchange of bodily fluids (8.2%), warts on hands or feet touching the genital area (1.7%), kissing (1%), sharing underwear, towels, or drinking glasses, and toilet seats (< 1%). There was no significant gender difference in the percentage of youth who selected the correct answer (p < 0.06) (Table 2).

Table 2
HPV transmission knowledge by gender among Latino Alternative High School Students (N=414)

Regarding HPV risk reduction knowledge, approximately three-quarters (72.8%) selected condom use as an effective risk reduction strategy, with smaller percentages selecting avoiding multiple partners (55.8%), abstinence (47.5%), monogamous relationships (26.8%) and HPV vaccination (22.3%). Most youth (88.0% to 91.5%) correctly identified spermicides, oral contraceptive pills, and eating a healthy diet as ineffective strategies for reducing the risk of contracting HPV. There were no differences by gender in the percentage of youth who correctly identified effective risk reduction strategies.

HPV risk perception

Only 27 youth (6.5%) perceived themselves to be at high risk for contracting HPV. The majority (93.5%) perceived themselves to be at “somewhat” or “extremely” low risk or was not sure of their risk level. Youth who perceived themselves at high risk reported an average of 2.8 reasons for being at risk. The most commonly reported reasons were: having had sex without a condom (reported by 74.1% of youth self-identifying as high risk), being sexually experienced (63.0%), having had multiple sexual partners (44.4%), and not knowing their partner’s sexual disease history (40.7%). Youth who perceived themselves at low risk reported an average of 2.4 reasons for being at low risk. The most commonly reported reasons were: taking good care of oneself (reported by 48.0% of youth self-identifying as low risk), not being sexually experienced (40.9%), always using a condom (27.2%), remaining monogamous (26.8%), being healthy with no symptoms (20.1%), asking about their partner’s sexual disease history (19.7%), and having had a recent check-up (18.9%). There no significant differences by gender in perceived reasons for being at high or low risk.

Regarding the STIs that youth were most concerned about contracting, only one student (a female) selected HPV as her greatest concern; 58.6% of all youth were most concerned about contracting HIV, 12.6% were most concerned about herpes, 1.9% about crabs, and less than 1% about the other STIs listed. No differences were reported by gender.

Regression analyses to examine associations between demographic variables, sexual behavior, HPV knowledge, and HPV risk perception indicated a significant association for mothers’ place of birth only – youth whose mothers were born outside of the U.S. had significantly lower HPV knowledge than those with American-born mothers (parameter estimate = −1.66, SE = 0.16, p < 0.007).

Discussion

By examining HPV knowledge and risk perception among a sample of Latino alternative school students in Houston, TX, this study expands our knowledge regarding HPV awareness among a high-risk, adolescent population. Although approximately two-thirds of the sample was sexually experienced, the majority reported limited knowledge regarding the consequences, symptoms, and prevalence of HPV, low to moderate knowledge regarding modes of transmission and risk reduction strategies, and very low perceptions of risk for contracting the virus. These findings are worrisome given the high prevalence of HPV among youth in the U.S.

Other studies of youth in the U.S. have shown modest knowledge regarding HPV. (Brewer, N. T. & Fazekas, K. I., 2007) In the current study, youth severely underestimated the prevalence of HPV among young people and few were aware of the potential negative health consequences. Regarding knowledge of effective strategies to reduce the risk of contracting HPV, the majority identified condom use ahead of abstinence, monogamous relationships, or avoiding multiple partners. While latex condoms may provide some level of risk reduction, HPV can infect areas that are not covered by a condom. More research is needed to assess the degree of protection latex condoms provide for both HPV infection and HPV-associated disease.(Centers for Disease Control and Prevention, 2007a) Low levels of awareness regarding HPV vaccination as an effective risk reduction strategy most likely reflect the timing of data collection which occurred prior to June 2006 when the U.S. Advisory Committee on Immunization Practices (ACIP) voted to recommend use of the HPV vaccine(Centers for Disease Control and Prevention, 2007b) and prior to ensuing public health and pharmaceutical company promotion regarding vaccination.

Previous studies among youth have reported increased HPV knowledge and risk perception among sexually active individuals;(Gerend, M. A. & Magloire, Z. F., 2008) however, in the current study sexual behavior was significantly associated with neither. Furthermore, there were no significant associations between HPV knowledge or risk perception with demographic variables such as gender or place of birth. The only demographic variable to show a significant inverse association with HPV knowledge was mother’s place of birth. Youth whose mothers were born outside of the U.S. had significantly lower knowledge regarding the consequences, symptoms, and prevalence of HPV compared to youth with U.S.-born mothers. This may reflect lower knowledge regarding HPV among the foreign-born mothers, parents’ reluctance to give information to their child because of fear it will promote sexual activity, or possibly lower levels of comfort or communication in discussing sexual topics with their child.(Marin, B. V. & Gomez, C. A., 1997; Baumeister, L. M., Flores, E., & Marin, B. V., 1995; Guilamo-Ramos, V. et al., 2006) Further research is needed to explore the influence of parental beliefs about sexual communication across different Latino cultures.

A number of limitations in the study design must be noted. First, youth with limited English proficiency were excluded from the study; therefore, findings may not be generalizable to Latino alternative school youth who have more recently immigrated to the U.S. Second, the study was conducted in nine alternative schools in Houston, TX; therefore, any generalization to alternative school youth in other geographic locations or to other Latino youth populations should be made with caution. Thirdly, these data were collected prior to FDA approval of HPV vaccinations; therefore, it is not possible to assess whether subsequent public health and pharmaceutical marketing efforts to promote HPV vaccines have enhanced levels of knowledge and risk related to HPV in this population.

Regardless of these limitations, these findings provide further evidence of limited knowledge and low perceived risk regarding HPV among a high-risk youth population, and indicate the need for enhanced educational efforts among Latino alternative school youth regarding the prevalence of HPV and effective ways to reduce the risk of infection. Potential strategies include interactive activities to address the prevalence and negative health consequences of HPV; skills-training activities, such as role plays, to help youth practice effective refusal and communication skills related to abstinence or condom use; and finally, information for youth and their parents to promote awareness and uptake of the HPV vaccines. Integration of activities into existing science or health education curricula would help to reduce the risks associated with HPV in a highly vulnerable adolescent population.

Table 3
Knowledge of effective and ineffective HPV risk reduction strategies by gender among Latino Alternative High School Students (N=414)

Reference

  • Baumeister LM, Flores E, Marin BV. Sex information given to Latina adolescents by parents. Health Education Research. 1995;10:233–239.
  • Becker MH. The health belief model and personal health behavior. Health Education Monographs. 1974;2:324–508.
  • Bosch FX, Lorincz A, Munoz N, Meijer CJ, Shah KV. The causal relation between human papillomavirus and cervical cancer. J Clin Pathol. 2002;55:244–265. [PMC free article] [PubMed]
  • Brewer NT, Fazekas KI. Predictors of HPV vaccine acceptability: a theory-informed, systematic review. Preventive Medicine. 2007;45:107–114. [PubMed]
  • Centers for Disease Control and Prevention Report to Congress: Prevention of Genital Human Papillomavirus Infection. [5-1-2008]. 2004. [Announcement posted on the World Wide Web]. from the World Wide Web: http://www.cdc.gov/std/HPV/2004HPV%20report.pdf.
  • Centers for Disease Control and Prevention Genital HPV [CDC Fact Sheet] [4-10-2008a]. 2007a. [Announcement posted on the World Wide Web]. from the World Wide Web: http://www.cdc.gov/std/HPV/hpv-fact-sheet-press.pdf.
  • Centers for Disease Control and Prevention Human Papillomavirus: HPV Information for Clinicians. [4-28-2008b]. 2007b. [Announcement posted on the World Wide Web]. from the World Wide Web: http://www.cdc.gov/std/hpv/common-clinicians/ClinicianBro-fp.pdf.
  • Centers for Disease Control and Prevention Youth Risk Beahvior Surveillance--Comprehensive Results, 1991-2005, Sexual Behaviors. [4-28-2008c]. 2007c. [Announcement posted on the World Wide Web]. from the World Wide Web: http://apps.nccd.cdc.gov/yrbss/
  • Centers for Disease Control and Prevention Oral Abstract D4a: Prevalence of sexually transmitted infections and bacterial vaginosis among female adolescents in the United States: Data from the National Health and Nutritional Examination Survey (NHANES) 2003-2004. [4-28-2008]. 2008. [Announcement posted on the World Wide Web].
  • Chesson HW, Blandford JM, Gift TL, Tao G, Irwin KL. The estimated direct medical cost of sexually transmitted diseases among American youth, 2000. Perspectives on Sexual and Reproductive Health. 2004;36:11–19. [PubMed]
  • Eaton DK, Kann L, Kinchen S, Ross J, Hawkins J, Harris WA, Lowry R, McManus T, Chyen D, Shanklin S, Lim C, Grunbaum JA, Wechsler H. Youth risk behavior surveillance--United States, 2005. MMWR Surveillance Summaries. 2006;55:1–108. [PubMed]
  • Gerend MA, Magloire ZF. Awareness, knowledge, and beliefs about human papillomavirus in a racially diverse sample of young adults. Journal of Adolescent Health. 2008;42:237–242. [PubMed]
  • Gribble JN, Miller HG, Rogers SM, Turner CF. Interview mode and measurement of sexual behaviors: Methodological issues. Journal of Sex Research. 1999;36:16–24. [PMC free article] [PubMed]
  • Grunbaum JA, Kann L, Kinchen SA, Ross JG, Gowda VR, Collins JL, Kolbe LJ. Youth Risk Behavior Surveillance. National Alternative High School Youth Risk Behavior Survey, United States, 1998. Journal of School Health. 2000;70:5–17. [PubMed]
  • Guilamo-Ramos V, Dittus P, Jaccard J, Goldberg V, Casillas E, Bouris A. The Content and Process of Mother--Adolescent Communication about Sex in Latino Families. Social Work Res. 2006;30:169–181.
  • Kann L, Kinchen SA, Williams BI, Ross JG, Lowry R, Grunbaum JA, Kolbe LJ, State and local YRBSS Coordinators Youth Risk Behavior Surveillance--United States, 1999. MMWR Surveillance Summaries. 2000;49:1–96. [PubMed]
  • Kleiner B, Porch R, Farris E. National Center for Education Statistics; Washington, DC: 2002. Public Alternative Schools and Programs for Students At Risk of Education Failure: 2000-01 (NCES 2002-004) U.S. Department of Education. http://nces.ed.gov/pubsearch/pubsinfo.asp?pubid=2002004.
  • Marin BV, Gomez CA. Latino culture and sex: Implications for HIV prevention. In: Garcia JG, Zea MC, editors. Psychological Interventions and Research with Latino Populations. Allyn & Bacon; Boston, MA: 1997. pp. 73–93.
  • Parkin DM, Bray F. Chapter 2: The burden of HPV-related cancers. Vaccine. 2006;24:s11–s25. [PubMed]
  • Ramirez JE, Ramos DM, Clayton L, Kanowitz S, Moscicki AB. Genital human papillomavirus infections: knowledge, perception of risk, and actual risk in a nonclinic population of young women. Journal of Women’s Health. 1997;6:113–121. [PubMed]
  • Romer D, Hornik R, Stanton B, Black M, Li XM, Ricardo I, Feigelman S. “Talking” computers: A reliable and private method to conduct interviews on sensitive topics with children. Journal of Sex Research. 1997;34:3–9.
  • Tortolero SR, Markham CM, Parcel GS, Peters RJ, Jr., Escobar-Chaves SL, Basen-Engquist K, Lewis HL. Using Intervention Mapping to adapt an effective HIV, sexually transmitted disease, and pregnancy prevention program for high-risk minority youth. Health Promotion Practice. 2005;6:286–298. [PubMed]
    Weinstock H, Berman S, Cates W., Jr. Sexually transmitted diseases among American youth: incidence and prevalence estimates, 2000. Perspectives on Sexual and Reproductive Health. 2004. [Announcement posted on the World Wide Web]. from the World Wide Web: http://www.guttmacher.org/pubs/journals/3600604.html.
  • Weller NF, Tortolero SR, Kelder SH, Grunbaum JA, Carvajal SC, Gingiss PM. Health risk behaviors of Texas students attending dropout prevention/recovery schools in 1997. Journal of School Health. 1999;69:22–28. [PubMed]
  • World Health Organization Vaccines against human papillomavirus. [5-1-2008]. 2001. [Announcement posted on the World Wide Web]. from the World Wide Web: http://www.who.int/vaccines/en/hpvrd.shtml/shtml.
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