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1.  Prevalence of and Risk Factors for Oral Human Papillomavirus Among Young Women in Costa Rica 
The Journal of Infectious Diseases  2013;208(10):1643-1652.
Background. Little is known about the epidemiology of oral human papillomavirus (HPV) in Latin America.
Methods. Women (N = 5838) aged 22–29 in the control and vaccine arms of an HPV-16/18 vaccine trial in Costa Rica had oral, cervical, and anal specimens collected. Samples were tested for alpha mucosal HPV types (SPF10/LiPA25 version 1); a subset of oral samples (n = 500) was tested for cutaneous HPV types in the genera alpha, beta, gamma, mu, and nu.
Results. In the control arm (n = 2926), 1.9% of women had an oral alpha mucosal HPV detected, 1.3% had carcinogenic HPV, and 0.4% had HPV-16; similar patterns for non-16/18 HPV types were observed in the vaccine arm. Independent risk factors for any oral alpha mucosal HPV among women in the control arm included marital status (adjusted odds ratio [AOR], 3.2; 95% confidence interval [CI], 1.8–5.7 for single compared to married/living as married), number of sexual partners (AOR, 2.4; 95% CI, 1.0–6.1 for ≥4 partners compared to 0–1 partners), chronic sinusitis (AOR, 3.1; 95% CI, 1.5–6.7), and cervical HPV infection (AOR, 2.6; 95% CI, 1.4–4.6). Detection of beta HPV was common (18.6%) and not associated with sexual activity.
Conclusions. Unlike cutaneous HPV types, alpha mucosal HPV types were uncommon in the oral region and were predominately associated with sexual behavior.
Clinical Trials Registration. NCT00128661.
PMCID: PMC3805238  PMID: 24014882
human papillomavirus vaccine; HPV; oropharynx cancer; Costa Rica; Guanacaste; oral HPV DNA
2.  Prevention Strategies for Gastric Cancer: A Global Perspective 
Clinical Endoscopy  2014;47(6):478-489.
Despite the substantial burden of gastric cancer worldwide, population strategies for primary prevention have not been introduced in any country. Recognizing the causal role of Helicobacter pylori infection, there is increasing interest in population-based programs to eradicate the infection to prevent gastric cancer. Nonetheless, the paucity of available evidence on feasibility and effectiveness has prevented implementation of this approach. There are very few secondary prevention programs based on screening with endoscopy or radiography, notably in the Republic of Korea and Japan, two of the countries with the highest incidence rates of gastric cancer. In Korea, where the organized screening program is in place, survival rate of gastric cancer is as high as 67%. More research is needed to quantify the specific contribution of the screening program to observed declines in mortality rates. Gastric cancer screening is unlikely to be feasible in many Low-Middle Income Countries where the gastric cancer burden is high. Prevention strategies are still under development and the optimal approach may differ depending on local conditions and societal values. The present review gives an overview of the etiology and burden of the disease, and possible prevention strategies for countries and regions confronted with a significant burden of disease.
PMCID: PMC4260094  PMID: 25505712
Stomach neoplasms; Prevention; Mass screening
3.  Factors Associated with IgA and IgG Fluctuations at the Cervix during the Menstrual Cycle 
The Journal of infectious diseases  2009;199(3):455-463.
The objective of this analysis was to describe patterns and determinants of cervical immunoglobulins A (IgA) and G (IgG) during the menstrual cycle.
One hundred and fifty four women who attended three visits coinciding with follicular, peri-ovulatory, and luteal phases of menstrual cycle were studied. Cervical secretions were collected at each visit for total IgA and IgG determination. Questionnaires administered at each visit inquired about demographics and behavioral practices.
Total IgA and IgG levels were higher among oral contraceptive (OC) users than naturally-cycling women. IgA and IgG levels declined at mid-cycle particularly among OC-users. After adjusting for time in cycle, specimen weight, and blood in the sample, reporting a recent illness was associated with lower IgA and IgG, and increasing age was associated with higher IgA and IgG among OC-users and non-OC users. Increased pregnancies were associated with higher IgA among non-OC users, and higher IgG among OC-users. Change in immunoglobulin levels between visits was associated with sample weight and presence of blood among both OC-users and non-users.
Time in cycle and OCs were significant determinants of cervical IgA and IgG levels. Role of endogenous and exogenous hormones on cervical immunoglobulins levels should be further investigated.
PMCID: PMC4158917  PMID: 19133811
cervical; IgA; IgG; menstrual cycle
4.  Cigarette, Cigar, and Pipe Smoking and the Risk of Head and Neck Cancers: Pooled Analysis in the International Head and Neck Cancer Epidemiology Consortium 
American Journal of Epidemiology  2013;178(5):679-690.
Cigar and pipe smoking are considered risk factors for head and neck cancers, but the magnitude of effect estimates for these products has been imprecisely estimated. By using pooled data from the International Head and Neck Cancer Epidemiology (INHANCE) Consortium (comprising 13,935 cases and 18,691 controls in 19 studies from 1981 to 2007), we applied hierarchical logistic regression to more precisely estimate odds ratios and 95% confidence intervals for cigarette, cigar, and pipe smoking separately, compared with reference groups of those who had never smoked each single product. Odds ratios for cigar and pipe smoking were stratified by ever cigarette smoking. We also considered effect estimates of smoking a single product exclusively versus never having smoked any product (reference group). Among never cigarette smokers, the odds ratio for ever cigar smoking was 2.54 (95% confidence interval (CI): 1.93, 3.34), and the odds ratio for ever pipe smoking was 2.08 (95% CI: 1.55, 2.81). These odds ratios increased with increasing frequency and duration of smoking (Ptrend ≤ 0.0001). Odds ratios for cigar and pipe smoking were not elevated among ever cigarette smokers. Head and neck cancer risk was elevated for those who reported exclusive cigar smoking (odds ratio = 3.49, 95% CI: 2.58, 4.73) or exclusive pipe smoking (odds ratio = 3.71, 95% CI: 2.59, 5.33). These results suggest that cigar and pipe smoking are independently associated with increased risk of head and neck cancers.
PMCID: PMC3755640  PMID: 23817919
head and neck neoplasms; smoking
5.  Impact of Human Papillomavirus Vaccination on Cervical Cytology Screening, Colposcopy, and Treatment 
American Journal of Epidemiology  2013;178(5):752-760.
The impact of human papillomavirus (HPV) vaccination on cervical screening, colposcopy, and treatment is incompletely understood. In 2004–2005, investigators in the Costa Rica Vaccine Trial randomized 7,466 women aged 18–25 years, 1:1, to receive HPV vaccination or hepatitis A vaccination. The worst-ever cytology diagnosis and the 4-year cumulative proportions of colposcopy referral and treatment by vaccination arm were compared for 2 cohorts. The total vaccinated cohort included 6,844 women who provided cervical samples. The naive cohort included 2,284 women with no evidence of previous HPV exposure. In the total vaccinated cohort, HPV-vaccinated women had a significant (P = 0.01) reduction in cytological abnormalities: 12.4% for high-grade lesions and 5.9% for minor lesions. Colposcopy referral was reduced by 7.9% (P = 0.03) and treatment by 11.3% (P = 0.24). Greater relative reductions in abnormal cytology (P < 0.001) were observed for HPV-vaccinated women in the naive cohort: 49.2% for high-grade lesions and 18.1% for minor lesions. Colposcopy referral and treatment were reduced by 21.3% (P = 0.01) and 45.6% (P = 0.08), respectively, in the naive cohort. The overall impact on health services will be modest in the first years after vaccine introduction among young adult women, even in regions with high coverage.
PMCID: PMC3755646  PMID: 23843026
cervical cancer; HPV; HPV vaccination; human papillomavirus; screening
6.  Management of Helicobacter pylori infection in Latin America: A Delphi technique-based consensus 
World Journal of Gastroenterology : WJG  2014;20(31):10969-10983.
AIM: To optimize diagnosis and treatment guidelines for this geographic region, a panel of gastroenterologists, epidemiologists, and basic scientists carried out a structured evaluation of available literature.
METHODS: Relevant questions were distributed among the experts, who generated draft statements for consideration by the entire panel. A modified three-round Delphi technique method was used to reach consensus. Critical input was also obtained from representatives of the concerned medical community. The quality of the evidence and level of recommendation supporting each statement was graded according to United States Preventive Services Task Force criteria.
RESULTS: A group of ten experts was established. The survey included 15 open-ended questions that were distributed among the experts, who assessed the articles associated with each question. The levels of agreement achieved by the panel were 50% in the first round, 73.3% in the second round and 100% in the third round. Main consensus recommendations included: (1) when available, urea breath and stool antigen test (HpSA) should be used for non-invasive diagnosis; (2) detect and eradicate Helicobacter pylori (H. pylori) in all gastroscopy patients to decrease risk of peptic ulcer disease, prevent o retard progression in patients with preneoplastic lesions, and to prevent recurrence in patients treated for gastric cancer; (3) further investigate implementation issues and health outcomes of H. pylori eradication for primary prevention of gastric cancer in high-risk populations; (4) prescribe standard 14-d triple therapy or sequential therapy for first-line treatment; (5) routinely assess eradication success post-treatment in clinical settings; and (6) select second- and third-line therapies according to antibiotic susceptibility testing.
CONCLUSION: These achievable steps toward better region-specific management can be expected to improve clinical health outcomes.
PMCID: PMC4138478  PMID: 25152601
Helicobacter pylori; Consensus development conference; Delphi technique; Latin America
7.  Evaluation of Systemic and Mucosal Anti-HPV16 and 18 Antibody Responses from Vaccinated Women 
Vaccine  2008;26(0):3608-3616.
Ideal methods to monitor HPV neutralizing antibodies induced by vaccination have not been established yet. Here, we evaluated systemic and cervical antibody levels induced by HPV16/18 AS04-adjuvanted vaccine (GlaxoSmithKline Biologicals) using a secreted alkaline phosphatase neutralization assay (SEAP) and ELISA. Serum and cervical secretions from 50 vaccinated women were used to assess 1) overall assay reproducibility, 2) inter-assay and inter-specimen correlation; 3) correlations between month 1 and month 12 titers. Strong correlations between SEAP-NA and ELISA were observed (serum anti-HPV16/18, ρ=0.91/0.85; cervix anti-HPV16/18, ρ=0.84/0.89). Systemic and cervical antibody measures also correlated well (ρ range: 0.64 – 0.75); except at mid-cycle (ρ range: 0.28 – 0.65). Correlations between antibody levels at one and twelve months following the start of vaccination were poor (ρ range: 0.16 – 0.38). In conclusion, HPV16/18 VLP-based ELISA is a reliable and valid method to monitor anti-HPV16/18 neutralizing potential for the first year following vaccination; however, additional studies will be required to better define the effects of the time on cycle and patterns of antibody response over time following vaccination.
PMCID: PMC4131294  PMID: 18541349
Human papillomavirus; Neutralization Assay; cervical secretions
8.  Adult height and head and neck cancer: a pooled analysis within the INHANCE Consortium 
Several epidemiological studies have shown a positive association between adult height and cancer incidence. The only study conducted among women on mouth and pharynx cancer risk, however, reported an inverse association. This study aims to investigate the association between height and the risk of head and neck cancer (HNC) within a large international consortium of HNC.
We analyzed pooled individual-level data from 24 case-control studies participating in the International Head and Neck Cancer Epidemiology Consortium. Odds Ratios (ORs) and 95% Confidence Intervals (CIs) were estimated separately for men and women for associations between height and HNC risk. Educational level, tobacco smoking, and alcohol consumption were included in all regression models. Stratified analyses by HNC subsites were performed.
This project included 17,666 cases and 28,198 controls. We found an inverse association between height and HNC (adjusted OR per 10 cm height =0.91, 95% CI 0.86–0.95 for men; adjusted OR=0.86, 95% CI 0.79–0.93 for women). In men, the estimated OR did vary by educational level, smoking status, geographic area, and control source. No differences by subsites were detected.
Adult height is inversely associated with HNC risk. As height can be considered a marker of childhood illness and low energy intake, the inverse association is consistent with prior studies showing that HNC occur more frequently among deprived individuals. Further studies designed to elucidate the mechanism of such association would be warranted.
PMCID: PMC4122122  PMID: 24271556
9.  Cross-protective vaccine efficacy of the bivalent HPV vaccine against HPV31 is associated with humoral immune responses 
Human Vaccines & Immunotherapeutics  2013;9(7):1399-1406.
Background: We investigated the role of antibody responses as potential mechanism for the cross-protective vaccine-efficacies (VE) observed from randomized clinical trials of the HPV16/18 bivalent vaccine.
Results: HPV31 cases had lower HPV16 antibody levels than controls (OR4th quartile compared with 1st quartile = 0.63; 95%CI: 0.36–1.08; p-trend = 0.03). HPV31 cases were also less likely to have detectable HPV31 neutralization, and HPV16 avidity than controls. No statistically significant differences by HPV18 antibody or HPV45 neutralization were observed among HPV45 cases and controls. Protection against HPV58 was not associated with any of the markers, confirming the specificity of our findings.
Methods: Samples are from three-dose HPV vaccine recipients from the Costa Rica HPV16/18 vaccine trial. Women with a new HPV31, HPV45, or HPV58 infections over four years of follow-up were compared with randomly selected control women—with no new infection with HPV31/45/58—with respect to HPV16 and HPV18 antibody, HPV31, HPV45, and HPV58 neutralization, and HPV16 avidity.
Conclusions: High HPV16 levels and avidity, and the ability to neutralize HPV31 were associated with protection against newly detected HPV31 infections, suggesting that the partial VE demonstrated for HPV31 is likely to be mediated at least in part through antibodies induced by HPV16/18 vaccination.
PMCID: PMC3974884  PMID: 23571174
HPV vaccine; humoral; immune response; cross-protection; mechanisms for protection
10.  High load for most high risk human papillomavirus genotypes is associated with prevalent cervical cancer precursors but only HPV16 load predicts the development of incident disease 
Cervicovaginal human papillomavirus (HPV) viral load has been purported as a potential marker for the detection of high-grade cervical intraepithelial neoplasia or cancer (≥CIN2). To examine disease association with type-specific viral load for the full-range of anogenital HPV infections, we conducted cross-sectional and prospective analyses of ∼2,000 HPV-infected women from a 10,000-woman population-based study in Guanacaste, Costa Rica with 7 years of follow-up. Cervical specimens were tested for >40 HPV types using a MY09/MY11 L1 consensus primer PCR method with type-specific dot blot hybridization and PCR signal intensity as a measure of viral load. A positive association was observed between prevalent ≥CIN2 and high viral load compared to low viral load for women with baseline single HPV16 infections (OR = 19.2, 95% CI = 4.4–83.2) and single non-16 carcinogenic infections (OR = 9.2, 95% CI = 2.1–39.9). Inclusion of women with multiple HPV types did not substantially change these associations. In prospective follow-up, only women infected with HPV16 alone (OR = 27.2, 95% = 3.5-213.5) had a strong association between high viral load and incident ≥CIN2; non-16 carcinogenic high viral load was not associated with incident ≥CIN2 (OR = 0.7, 95% CI = 0.2–1.9). Single noncarcinogenic type viral load was not associated with increased risk of prevalent or incident ≥CIN2 (OR = 1.2 and 1.1, respectively). In conclusion, carcinogenic high viral load was associated with prevalent ≥CIN2; however HPV16 was uniquely associated with incident ≥CIN2. The extent to which these observations can be translated into clinical practice must be rigorously examined in the context of the method of viral load measurement and the type-specific differences observed for incident ≥CIN2.
PMCID: PMC3962984  PMID: 17722112
human papillomavirus; viral load; genotype; screening
11.  Identification and characterization of two novel human papillomaviruses (HPVs) by overlapping PCR: HPV102 and HPV106 
The Journal of general virology  2007;88(0 11):2952-2955.
Complete genomes of HPV102 (8078 bp) and HPV106 (8035 bp) were PCR amplified and cloned from cervicovaginal cells of a 49-year-old Hispanic female with reactive changes on her Pap test and a 42-year-old Hispanic female with a Pap test diagnosis of atypical squamous cells of unknown significance (ASCUS), respectively. The nucleotide sequence similarity of the complete L1 open reading frame (ORF) determined that HPV102 and HPV106 are most closely related to HPV83 (84.1 % identity) and HPV90 (83.5 % identity), respectively, placing them in the genital HPV groups, papillomaviruses species α3 and α15. HPV102 and HPV106 contain five early genes (E6, E7, E1, E2, and E4) and two late genes (L2 and L1), and both lack an E5 ORF. On the basis of phylogenetic analyses and available clinical information, these two novel HPV types expand the heterogeneity of HPVs detected in the lower genital tract.
PMCID: PMC3963832  PMID: 17947516
12.  A Comparison of Cervical and Vaginal Human Papillomavirus 
Sexually transmitted diseases  2007;34(11):849-855.
We wanted to compare detection of a broad spectrum of human papillomavirus (HPV) types detected in cellular specimens from the vagina and cervix, which could provide information about the potential of each anatomical site for harboring infection. Previous studies have failed to present data on or detect a broad spectrum of HPV genotypes and/or have not carefully sampled the vagina, instead relying on self-collection that is likely contaminated with cervical cells.
Study Design
We conducted follow-up study of 353 women who had participated in study of HPV and cervical neoplasia in Costa Rica. We collected paired cervical and vaginal specimens; vaginal specimens were collected from the fornix to minimize cervical contamination. Specimens were tested in a masked fashion for >40 HPV types using a MY09/MY11 PCR method and type-specific dot blot hybridization.
The prevalence for any carcinogenic HPV type in vaginal and cervical specimens was similar (P = 0.3). However, the prevalence for any HPV type in vaginal specimens was greater than in cervical specimens (P = 0.0002), primarily due to a twofold increased vaginal prevalence of HPV types of the α3/α15 phylogenetic species (e.g., HPV61) (P <0.00005).
Carcinogenic HPV types appeared to have a similar affinity for vaginal and cervical epithelium, but noncarcinogenic HPV types of the α3/α15 phylogenetic species may have a tropism for vaginal epithelium.
PMCID: PMC3962831  PMID: 17621246
13.  Elevated methylation of HPV16 DNA is associated with the development of high grade cervical intraepithelial neoplasia 
We explored the association of HPV16 DNA methylation with age, viral load, viral persistence, and risk of incident and prevalent high grade CIN (CIN2+) in serially collected specimens from the Guanacaste, Costa Rica cohort. 273 exfoliated cervical cell specimens (diagnostic and pre-diagnostic) were selected: 1) 92 with HPV16 DNA clearance (controls), 2) 72 with HPV16 DNA persistence (without CIN2+), and 3) 109 with CIN2+. DNA was extracted, bisulfite converted and methylation was quantified using pyrosequencing assays at 66 CpGs across the HPV genome. The Kruskal-Wallis test was used to determine significant differences among groups, and receiver operating characteristic curve analyses were used to evaluate how well methylation identified women with CIN2+. In diagnostic specimens, 88% of CpG sites had significantly higher methylation levels in CIN2+ after correction for multiple tests compared with controls. The highest AUC was 0.82 for CpG site 6457 in L1, and a diagnostic sensitivity of 91% corresponded to a specificity of 60% for CIN2+. Prospectively, 17% of CpG sites had significantly higher methylation in pre-diagnostic CIN2+ specimens (median time of 3 years before diagnosis) vs. controls. The strongest pre-diagnostic CpG site was 6367 in L1 with an AUC of 0.76. Age-stratified analyses suggested that women older than the median age of 28 years have an increased risk of precancer associated with high methylation. Higher methylation in CIN2+ cases was not explained by higher viral load. We conclude that elevated levels of HPV16 DNA methylation may be useful to predict concurrently diagnosed as well as future CIN2+.
PMCID: PMC3493709  PMID: 22847263
HPV16; methylation; epidemiology; receiver operating curve; biomarker
14.  Glutathione S-transferase L1 multiplex serology as a measure of cumulative infection with human papillomavirus 
BMC Infectious Diseases  2014;14:120.
Several assays are used to measure type-specific serological responses to human papillomavirus (HPV), including the bead-based glutathione S-transferase (GST)-L1 multiplex serology assay and virus-like particle (VLP)-based ELISA. We evaluated the high-throughput GST-L1, which is increasingly used in epidemiologic research, as a measure of cumulative HPV infection and future immune protection among HPV-unvaccinated women.
We tested enrollment sera from participants in the control arm of the Costa Rica Vaccine Trial (n = 488) for HPV16 and HPV18 using GST-L1, VLP-ELISA, and two assays that measure neutralizing antibodies (cLIA and SEAP-NA). With statistical adjustment for sampling, we compared GST-L1 serostatus to established HPV seropositivity correlates and incident cervical HPV infection using odds ratios. We further compared GST-L1 to VLP-ELISA using pair-wise agreement statistics and by defining alternate assay cutoffs.
Odds of HPV16 GST-L1 seropositivity increased with enrollment age (OR = 1.20 per year, 95%CI 1.03-1.40) and lifetime number of sexual partners (OR = 2.06 per partner, 95%CI 1.49-2.83), with similar results for HPV18. GST-L1 seropositivity did not indicate protection from incident infection over 4 years of follow-up (HPV16 adjusted OR = 1.72, 95%CI 0.95-3.13; HPV18 adjusted OR = 0.38, 95%CI 0.12-1.23). Seroprevalence by GST-L1 (HPV16 and HPV18, respectively) was 5.0% and 5.2%, compared to 19.4% and 23.8% by VLP-ELISA, giving positive agreement of 39.2% and 20.8%. Lowering GST-L1 seropositivity cutoffs improved GST-L1/VLP-ELISA positive agreement to 68.6% (HPV16) and 61.5% (HPV18).
Our data support GST-L1 as a marker of cumulative HPV infection, but not immune protection. At lower seropositivity cutoffs, GST-L1 better approximates VLP-ELISA.
PMCID: PMC3973893  PMID: 24588945
15.  Genetic Variants in Nicotine Addiction and Alcohol Metabolism Genes, Oral Cancer Risk and the Propensity to Smoke and Drink Alcohol: A Replication Study in India 
PLoS ONE  2014;9(2):e88240.
Genetic variants in nicotinic acetylcholine receptor and alcohol metabolism genes have been associated with propensity to smoke tobacco and drink alcohol, respectively, and also implicated in genetic susceptibility to head and neck cancer. In addition to smoking and alcohol, tobacco chewing is an important oral cancer risk factor in India. It is not known if these genetic variants influence propensity or oral cancer susceptibility in the context of this distinct etiology.
We examined 639 oral and pharyngeal cancer cases and 791 controls from two case-control studies conducted in India. We investigated six variants known to influence nicotine addiction or alcohol metabolism, including rs16969968 (CHRNA5), rs578776 (CHRNA3), rs1229984 (ADH1B), rs698 (ADH1C), rs1573496 (ADH7), and rs4767364 (ALDH2).
The CHRN variants were associated with the number of chewing events per day, including in those who chewed tobacco but never smoked (P =  0.003, P =  0.01 for rs16969968 and rs578776 respectively). Presence of the variant allele contributed to approximately 13% difference in chewing frequency compared to non-carriers. While no association was observed between rs16969968 and oral cancer risk (OR =  1.01, 95% CI =  0.83– 1.22), rs578776 was modestly associated with a 16% decreased risk of oral cancer (OR =  0.84, 95% CI =  0.72– 0.98). There was little evidence for association between polymorphisms in genes encoding alcohol metabolism and oral cancer in this population.
The association between rs16969968 and number of chewing events implies that the effect on smoking propensity conferred by this gene variant extends to the use of smokeless tobacco.
PMCID: PMC3914962  PMID: 24505444
16.  Epidemiology of Helicobacter pylori infection in six Latin American countries (SWOG Trial S0701) 
Cancer causes & control : CCC  2012;24(2):209-215.
To investigate the potential determinants of Helicobacter pylori infection between adults 21–65 years old.
Data are from the initial screening visit of a randomized clinical trial of three antibiotic regimens to eradicate H. pylori, conducted in seven sites (Santiago–Chile, Túquerres–Colombia, Guanacaste–Costa Rica, Copán–Honduras, Obregón and Tapachula–México, León–Nicaragua). Thousand eight hundred and fifty-nine adults from the general population were screened for H. pylori infection using an urea breath test (UBT) and were interviewed to assess socioeconomic-, demographic-, and symptom-related characteristics. Logistic regression was used to assess the relationship between these characteristics and H. pylori positivity at enrollment.
Among the 1,852 eligible participants for whom a conclusive UBT result was obtained, H. pylori prevalence was 79.4 %, ranging from 70.1 to 84.7 % among the seven centers. Prevalence did not differ by sex (female: 78.4, male: 80.9; p = 0.20) or age (p = 0.08). H. pylori positivity increased with increasing number of siblings (p trend <0.0001). Participants with education beyond 12 years were less likely to be UBT-positive (OR 0.4: 0.3–0.6, compared to participants with 0–6 years of schooling) as were those employed outside the home (OR 0.7: 0.6–1.0). Odds of H. pylori infection increased with the presence of certain living conditions during childhood including having lived in a household with an earth floor (OR 1.8: 1.4–2.4), lack of indoor plumbing (OR 1.3: 1.0–1.8) and crowding (OR 1.4: 1.0–1.8, for having more than two persons per bedroom). Regarding current household conditions, living with more than 3 children in the household (OR 1.7: 1.2–2.5) and crowding (OR 1.8: 1.3–2.3) were associated with H. pylori infection.
The prevalence of H. pylori in adults was high and differed significantly among the six Latin American countries studied (p < 0.001). Our findings confirm the strong link between poor socioeconomic conditions and H. pylori infection.
PMCID: PMC3645498  PMID: 23263777
Helicobacter pylori; Infection; Prevalence; Risk factors; Determinants; Epidemiology
17.  Kinetic and HPV infection effects on cross-type neutralizing antibody and avidity responses induced by Cervarix® 
Vaccine  2012;31(1):165-170.
We previously demonstrated that Cervarix® elicits antibody responses against vaccine-related types for which clinical efficacy was demonstrated (HPV-31 and -45). Here, we evaluated the kinetics of neutralization titers and avidity of Cervarix®-induced antibodies up to 36 months of follow-up in unexposed and HPV infected women.
A subset of women who participated in the Cost Rica HPV-16/18 Vaccine Trial had pre- and post-vaccination sera tested for antibody responses to HPV-16, -18, -31, -45, and -58 using a pseudovirion-based neutralization assay, and HPV-16 antibody avidity using an HPV-16 L1 VLP (virus-like particle)-based ELISA developed in our laboratory.
In uninfected women, neutralizing antibody titers did not reach significance until after the 3rd dose for HPV-31 (month 12, p=0.009) and HPV-45 (month 12, p=0.003), but then persisted up to month 36 (HPV-31, p=0.01; HPV-45, p=0.002). Individuals infected with HPV-16 or HPV-31 at enrollment developed a significantly higher median antibody response to the corresponding HPV type after one dose, but there was not a difference between median titers after three doses compared to the HPV negative group. Median HPV-16 antibody avidity and titer increased over time up to month 12; however, the HPV-16 avidity did not correlate well with HPV-16 neutralizing antibody titers at each time point examined, except for month 6. The median avidity levels were higher in HPV-16 infected women at month 1 (p=0.04) and lower in HPV-16 infected women at month 12 (p=0.006) compared to the HPV negative women.
The persistence of cross-neutralization titers at month 36 suggests cross-reactive antibody responses are likely to persist long-term and are not influenced by infection status at enrollment. However, the weak correlation between avidity and neutralization titers emphasizes the need for examining avidity in efficacy studies to determine if high avidity antibodies play a critical role in protection against infection.
PMCID: PMC3527627  PMID: 23123024
Human papillomavirus; antibody; vaccine; avidity
18.  Vitamin or mineral supplement intake and the risk of head and neck cancer: pooled analysis in the INHANCE consortium 
To investigate the potential role of vitamin or mineral supplementation on the risk of head and neck cancer (HNC), we analyzed individual-level pooled data from 12 case-control studies (7,002 HNC cases and 8,383 controls) participating in the International Head and Neck Cancer Epidemiology consortium. There were a total of 2,028 oral cavity cancer, 2,465 pharyngeal cancer, and 874 unspecified oral/pharynx cancer, 1,329 laryngeal cancer and 306 overlapping HNC cases. Odds ratios (OR) and 95% confidence intervals (CIs) for self reported ever use of any vitamins, multivitamins, vitamin A, vitamin C, vitamin E, and calcium, beta-carotene, iron, selenium, and zinc supplements were assessed. We further examined frequency, duration and cumulative exposure of each vitamin or mineral when possible and stratified by smoking and drinking status. All ORs were adjusted for age, sex, race/ethnicity, study center, education level, and pack-years of smoking, frequency of alcohol drinking and fruit/vegetable intake. A decreased risk of HNC was observed with ever use of vitamin C (OR=0.76, 95% CI=0.59-0.96) and with ever use of calcium supplement (OR=0.64, 95% CI=0.42-0.97). The inverse association with HNC risk was also observed for 10 or more years of vitamin C use (OR=0.72, 95% CI=0.54-0.97) and more than 365 tablets of cumulative calcium intake (OR=0.36, 95% CI=0.16-0.83), but linear trends were not observed for the frequency or duration of any supplement intake. We did not observe any strong associations between vitamin or mineral supplement intake and the risk of head and neck cancer.
PMCID: PMC3376697  PMID: 22173631
vitamin supplement; mineral supplement; head and neck cancer
19.  Prevalence of and Risk Factors for Anal Human Papillomavirus Infection Among Young Healthy Women in Costa Rica 
The Journal of Infectious Diseases  2012;206(7):1103-1110.
Background. Anal cancer is caused by human papillomavirus (HPV), yet little is known about anal HPV infection among healthy young women.
Methods. A total of 2017 sexually active women in the control arm of an HPV-16/18 vaccine trial had a single anal specimen collected by a clinician at the 4-year study visit. Samples were tested for HPV by SPF10 PCR/DEIA/LiPA25, version 1.
Results. A total of 4% of women had HPV-16, 22% had oncogenic HPV, and 31% had any HPV detected in an anal specimen. The prevalence of anal HPV was higher among women who reported anal intercourse, compared with those who did not (43.4% vs 28.4%; P < .001). Among women who reported anal intercourse, cervical HPV (adjusted odds ratio [aOR], 5.3 [95% confidence interval {CI}, 3.4–8.2]), number of sex partners (aOR, 2.2 [95% CI, 1.1–4.6] for ≥4 partners), and number of anal intercourse partners (aOR, 1.9 [95% CI, 1.1–3.3] for ≥2 partners) were independent risk factors for anal HPV detection. Among women who reported no anal intercourse, cervical HPV (aOR, 4.7 [95% CI, 3.7–5.9]), number of sex partners (aOR, 2.4 [95% CI, 1.7–3.4] for ≥4 partners), and report of anal fissures (aOR, 2.3 [95% CI, 1.1–4.8]) were associated with an increased odds of anal HPV detection.
Conclusion. Anal HPV is common among young women, even those who report no anal sex, and was associated with cervical HPV infection. Anal fissures in women who report never having had anal intercourse may facilitate HPV exposure.
Clinical Trials Registration. NCT00128661.
PMCID: PMC3499109  PMID: 22850119
20.  Evolution and Taxonomic Classification of Alphapapillomavirus 7 Complete Genomes: HPV18, HPV39, HPV45, HPV59, HPV68 and HPV70 
PLoS ONE  2013;8(8):e72565.
The species Alphapapillomavirus 7 (alpha-7) contains human papillomavirus genotypes that account for 15% of invasive cervical cancers and are disproportionately associated with adenocarcinoma of the cervix. Complete genome analyses enable identification and nomenclature of variant lineages and sublineages.
The URR/E6 region was sequenced to screen for novel variants of HPV18, 39, 45, 59, 68, 70, 85 and 97 from 1147 cervical samples obtained from multiple geographic regions that had previously been shown to contain an alpha-7 HPV isolate. To study viral heterogeneity, the complete 8 kb genome of 128 isolates, including 109 sequenced for this analysis, were annotated and analyzed. Viral evolution was characterized by constructing phylogenic trees using maximum-likelihood and Bayesian algorithms. Global and pairwise alignments were used to calculate total and ORF/region nucleotide differences; lineages and sublineages were assigned using an alphanumeric system. The prototype genome was assigned to the A lineage or A1 sublineage.
The genomic diversity of alpha-7 HPV types ranged from 1.1% to 6.7% nucleotide sequence differences; the extent of genome-genome pairwise intratype heterogeneity was 1.1% for HPV39, 1.3% for HPV59, 1.5% for HPV45, 1.6% for HPV70, 2.1% for HPV18, and 6.7% for HPV68. ME180 (previously a subtype of HPV68) was designated as the representative genome for HPV68 sublineage C1. Each ORF/region differed in sequence diversity, from most variable to least variable: noncoding region 1 (NCR1) / noncoding region 2 (NCR2) > upstream regulatory region (URR) > E6 / E7 > E2 / L2 > E1 / L1.
These data provide estimates of the maximum viral genomic heterogeneity of alpha-7 HPV type variants. The proposed taxonomic system facilitates the comparison of variants across epidemiological and molecular studies. Sequence diversity, geographic distribution and phylogenetic topology of this clinically important group of HPVs suggest an independent evolutionary history for each type.
PMCID: PMC3745470  PMID: 23977318
21.  Reduced Prevalence of Oral Human Papillomavirus (HPV) 4 Years after Bivalent HPV Vaccination in a Randomized Clinical Trial in Costa Rica 
PLoS ONE  2013;8(7):e68329.
Human papillomavirus (HPV) infection, particularly with type 16, causes a growing fraction of oropharyngeal cancers, whose incidence is increasing, mainly in developed countries. In a double-blind controlled trial conducted to investigate vaccine efficacy (VE) of the bivalent HPV 16/18 vaccine against cervical infections and lesions, we estimated VE against prevalent oral HPV infections 4 years after vaccination.
Methods and Findings
A total of 7,466 women 18–25 years old were randomized (1∶1) to receive the HPV16/18 vaccine or hepatitis A vaccine as control. At the final blinded 4-year study visit, 5,840 participants provided oral specimens (91·9% of eligible women) to evaluate VE against oral infections. Our primary analysis evaluated prevalent oral HPV infection among all vaccinated women with oral and cervical HPV results. Corresponding VE against prevalent cervical HPV16/18 infection was calculated for comparison. Oral prevalence of identifiable mucosal HPV was relatively low (1·7%). Approximately four years after vaccination, there were 15 prevalent HPV16/18 infections in the control group and one in the vaccine group, for an estimated VE of 93·3% (95% CI = 63% to 100%). Corresponding efficacy against prevalent cervical HPV16/18 infection for the same cohort at the same visit was 72·0% (95% CI = 63% to 79%) (p versus oral VE = 0·04). There was no statistically significant protection against other oral HPV infections, though power was limited for these analyses.
HPV prevalence four years after vaccination with the ASO4-adjuvanted HPV16/18 vaccine was much lower among women in the vaccine arm compared to the control arm, suggesting that the vaccine affords strong protection against oral HPV16/18 infection, with potentially important implications for prevention of increasingly common HPV-associated oropharyngeal cancer., Registry number NCT00128661
PMCID: PMC3714284  PMID: 23873171
Alcohol and tobacco consumption are well recognized risk factors for head and neck cancer (HNC). Evidence suggests that genetic predisposition may also play a role. Only a few epidemiologic studies, however, have considered the relation between HNC risk and family history of HNC and other cancers. We pooled individual- level data across 12 case-control studies including 8,967 HNC cases and 13,627 controls. We obtained pooled odds ratios (OR) using fixed and random effect models, and adjusting for potential confounding factors. All statistical tests were two-sided. A family history of HNC in first-degree relatives increased the risk of HNC (OR=1.7, 95% confidence interval, CI, 1.2-2.3). The risk was higher when the affected relative was a sibling (OR=2.2, 95% CI 1.6-3.1) rather than a parent (OR=1.5, 95% CI 1.1-1.8), and for more distal HNC anatomic sites (hypopharynx and larynx). The risk was also higher, or limited to, subjects exposed to tobacco. The OR rose to 7.2 (95% CI 5.5-9.5) among subjects with family history, who were alcohol and tobacco users. A weak but significant association (OR=1.1, 95% CI 1.0-1.2) emerged for family history of other tobacco-related neoplasms, particularly with laryngeal cancer (OR=1.3, 95% CI 1.1-1.5). No association was observed for family history of non-tobacco related neoplasms and the risk of HNC (OR=1.0, 95% CI 0.9-1.1). Familial factors play a role in the etiology of HNC. In both subjects with and without family history of HNC, avoidance of tobacco and alcohol exposure may be the best way to avoid HNC.
PMCID: PMC3711193  PMID: 18814262
Head and neck cancer; family history; pooled analysis; tobacco; alcohol
23.  Rapid Clearance of Human Papillomavirus and Implications for Clinical Focus on Persistent Infections 
Health professionals and the public need to understand the natural history of human papillomavirus (HPV) infections of the cervix to best use the information provided by new molecular screening tests. We investigated outcomes of 800 carcinogenic HPV infections detected in 599 women at enrollment into a population-based cohort (Guanacaste, Costa Rica). For individual infections, we calculated cumulative proportions of three outcomes (viral clearance, persistence without cervical intraepithelial neoplasia grade 2 or worse [CIN2+], or persistence with new diagnosis of CIN2+) at successive 6-month time points for the first 30 months of follow-up. Cervical specimens were tested for carcinogenic HPV genotypes using an L1 degenerate-primer polymerase chain reaction method. Infections typically cleared rapidly, with 67% (95% confidence interval [CI] = 63% to 70%) clearing by 12 months. However, among infections that persisted at least 12 months, the risk of CIN2+ diagnosis by 30 months was 21% (95% CI = 15% to 28%). The risk of CIN2+ diagnosis was highest among women younger than 30 years with HPV-16 infections that persisted for at least 12 months (53%; 95% CI = 29% to 76%). These findings suggest that the medical community should emphasize persistence of cervical HPV infection, not single-time detection of HPV, in management strategies and health messages.
PMCID: PMC3705579  PMID: 18364507
24.  Behavioral/Lifestyle and Immunologic Factors Associated with HPV Infection among Women Older Than 45 Years 
Cervical human papilloma virus (HPV) detection increases after menopause, but its determinants need clarification.
In a case–control study nested within a 10,049 women cohort, we evaluated women 45 to 75 years old who acquired HPV infection and were HPV positive 5 to 6 years after enrollment (N = 252), and HPV-negative women as matched controls (N = 265). Detailed sexual behavior and cellular immune response were investigated. Odds ratios (OR) and attributable fractions were estimated.
Women with 2+ lifetime partners had 1.7-fold (95% CI = 1.1–2.7) higher risk than monogamous women, with similar findings if their partners had other partners. Women with 2+ partners after last HPV-negative result had the highest risk (OR = 3.9; 95% CI = 1.2–12.4 compared with 0–1 partners). Weaker immune response to HPV-16 virus-like particles increased risk (OR = 1.7; 95% CI = 1.1–2.7 comparing lowest to highest tertile). Among women with no sexual activity in the period before HPV appearance, reduced immune response to phytohemagglutinin was the only determinant (OR = 2.9; 95% CI = 0.94–8.8). Twenty-one percent of infections were explained by recent sexual behavior, 21% by past sexual behavior, and 12% by reduced immune response.
New infections among older women may result from sexual activity of women and/or their partners or reappearance of past (latent) infections possibly related to weakened immune response.
HPV infections among older women are associated with current and past sexual exposures and possibly with immune senescence. The risk of cancer from these infections is likely to be low but could not be fully evaluated in the context of this study.
PMCID: PMC3703390  PMID: 20952561
25.  Long-term risk of recurrent cervical HPV infection and precancer and cancer following excisional treatment 
Risk of recurrent CIN2+ (including cervical intraepithelial neoplasia grade 2 [CIN2], CIN3, carcinoma and in situ, adenocarcinoma in situ or cancer) remains elevated for years following treatment. The role of long-term post-treatment HPV presence on subsequent risk of CIN2+ was evaluated in the 10,049-women Guanacaste cohort. 681 women were referred to colposcopy because of high-grade cytology, positive cervicography and/or suspicion of cancer based on visual assessment; 486 were judged to require treatment. After excluding women with <12 months of follow-up (N=88), prior cancer or hysterectomy (n=37) or other reasons (N=14), 347 were included in the analysis. Infections were categorized as persistent if present at both pre- and post-treatment visits and new if detected only post-treatment. Median time between the treatment and post-treatment visits was 6.7 years (IQR 3.8 to 7.8). At the post-treatment visit, 8 (2.4%), 2 (0.6%), and 8 (2.4%) of the 347 treated women had persistent HPV16, HPV18, or other carcinogenic HPV, respectively. Two (0.8%), 3 (1.0%), and 13 (4.0%) had new HPV16, HPV18, and other carcinogenic HPV, respectively. Six CIN2+ cases were identified at the post-treatment visit, all with persistent infections (three HPV16, one HPV18, and two other carcinogenic HPV). No recurrent disease was observed among women with new HPV infections during the follow-up period. Thus, persistence of HPV infection a median of six years after treatment was uncommon but, when present, posed a substantial risk of subsequent CIN2+. Serial follow-up data from other studies would further strengthen these conclusions.
PMCID: PMC3334438  PMID: 21823117

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