Global evaluation of lineage-specific human papillomavirus capsid antigenicity using antibodies elicited by natural infection.

Human Papillomavirus (HPV) type variants have been classified into lineages and sublineages based upon their whole genome sequence. Here we have examined the specificity of antibodies generated following natural infection with lineage variants of oncogenic types (HPV16, 18, 31, 33, 45, 52 and 58) by testing serum samples assembled from existing archives from women residing in Africa, The Americas, Asia or Europe against representative lineage-specific pseudoviruses for each genotype. We have subjected the resulting neutralizing antibody data to antigenic clustering methods and created relational antigenic profiles for each genotype to inform the delineation of lineage-specific serotypes. For most genotypes, there was evidence of differential recognition of lineage-specific antigens and in some cases of a sufficient magnitude to suggest that some lineages should be considered antigenically distinct within their respective genotypes. These data provide compelling evidence for a degree of lineage specificity within the humoral immune response following natural infection with oncogenic HPV.

The acute schistosomiasis mansoni ameliorates metabolic syndrome in the C57BL/6 mouse model.

Human and experimental studies have shown that chronic schistosomiasis mansoni protects against metabolic disorders through direct and indirect pathways. This study aims to investigate the co-morbidity between the acute schistosomiasis and nonalcoholic fatty liver. To address this, male C57BL/6 mice fed a high-fat chow (60% fat) or standard chow (10% fat) for 13 weeks and later infected with 80 Schistosoma mansoni cercariae. Mice were assigned into four groups: uninfected fed standard (USC), uninfected fed high-fat chow (UHFC), infected fed standard (ISC), and infected fed high-fat chow (IHFC). Blood sample and tissues were obtained at nine weeks post-infection (acute schistosomiasis) by necropsy. UHFC mice showed higher body mass, visceral adiposity, impaired glucose tolerance, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), triglyceride (TG), and liver steatosis compared to USC mice. IHFC mice showed lower blood lipid levels, blood glucose, improved glucose tolerance, body mass, and liver steatosis (macro and microvesicular) compared to UHFC mice. IHFC showed more massive histopathological changes (sinusoidal fibrosis, hepatocellular ballooning, and inflammatory infiltrates) compared to ISC. In conclusion, the co-morbidity results in both beneficial (friend) and detrimental (foe) for the host. While the acute schistosomiasis improves some metabolic features of metabolic syndrome, comorbidity worsens the liver injury.

Is chlamydia screening and testing in Britain reaching young adults at risk of infection? Findings from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3).

BACKGROUND: In the context of widespread opportunistic chlamydia screening among young adults, we aimed to quantify chlamydia testing and diagnosis among 16-24 year olds in Britain in relation to risk factors for prevalent chlamydia infection. METHODS: Using data from sexually experienced (≥1 lifetime sexual partner) 16-year-old to 24-year-old participants in Britain's third National Survey of Sexual Attitudes and Lifestyles (conducted 2010-2012), we explored socio-demographic and behavioural factors associated with prevalent chlamydia infection (detected in urine; n=1832), self-reported testing and self-reported diagnosis in the last year (both n=3115). RESULTS: Chlamydia prevalence was 3.1% (95% CI 2.2% to 4.3%) in women and 2.3% (1.5% to 3.4%) in men. A total of 12.3% of women and 5.3% men had a previous chlamydia diagnosis. Factors associated with prevalent infection were also associated with testing and diagnosis (eg, increasing numbers of sexual partners), with some exceptions. For example, chlamydia prevalence was higher in women living in more deprived areas, whereas testing was not. In men, prevalence was higher in 20-24 than 16-19 year olds but testing was lower. Thirty per cent of women and 53.7% of men with ≥2 new sexual partners in the last year had not recently tested. CONCLUSIONS: In 2010-2012 in Britain, the proportion of young adults reporting chlamydia testing was generally higher in those reporting factors associated with chlamydia. However, many of those with risk factors had not been recently tested, leaving potential for undiagnosed infections. Greater screening and prevention efforts among individuals in deprived areas and those reporting risk factors for chlamydia may reduce undiagnosed prevalence and transmission.

Can we use postal surveys with anonymous testing to monitor chlamydia prevalence in young women in England? Pilot study incorporating randomised controlled trial of recruitment methods.

OBJECTIVES: Chlamydia prevalence in the general population is a potential outcome measure for the evaluation of chlamydia control programmes. We carried out a pilot study to determine the feasibility of using a postal survey for population-based chlamydia prevalence monitoring. METHODS: Postal invitations were sent to a random sample of 2000 17-year-old to 18-year-old women registered with a general practitioner in two pilot areas in England. Recipients were randomised to receive either a self-sampling kit (n=1000), a self-sampling kit and offer of £5 voucher on return of sample (n=500) or a self-sampling kit on request (n=500). Participants returned a questionnaire and self-taken vulvovaginal swab sample for unlinked anonymous Chlamydia trachomatis testing. Non-responders were sent a reminder letter 3 weeks after initial invitation. We calculated the participation rate (number of samples returned/number of invitations sent) and cost per sample returned (including cost of consumables and postage) in each group. RESULTS: A total of 155/2000 (7.8%) samples were returned with consent for testing. Participation rates varied by invitation group: 7.8% in the group who were provided with a self-sampling kit, 14% in the group who were also offered a voucher and 1.0% in the group who were not sent a kit. The cost per sample received was lowest (£36) in the group who were offered both a kit and a voucher. CONCLUSIONS: The piloted survey methodology achieved low participation rates. This approach is not suitable for population-based monitoring of chlamydia prevalence among young women in England. STUDY REGISTRATION NUMBER: (UKCRN ID 10913).

High-Risk Human Papillomavirus (HPV) Infection and Cervical Cancer Prevention in Britain: Evidence of Differential Uptake of Interventions from a Probability Survey.

BACKGROUND: The third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3) provides an opportunity to explore high-risk human papillomavirus (HR-HPV) and uptake of cervical screening and HPV vaccination in the general population. METHODS: Natsal-3, a probability sample survey of men and women ages 16 to 74, resident in Britain, interviewed 8,869 women in 2010 to 2012. We explored risk factors for HR-HPV (in urine from 2,569 sexually experienced women ages 16 to 44), nonattendance for cervical screening in the past 5 years, and noncompletion of HPV catch-up vaccination. RESULTS: HR-HPV was associated with increasing numbers of lifetime partners, younger age, increasing area-level deprivation, and smoking. Screening nonattendance was associated with younger and older age, increasing area-level deprivation (age-adjusted OR 1.91, 95% confidence interval, 1.48-2.47 for living in most vs. least deprived two quintiles), Asian/Asian British ethnicity (1.96, 1.32-2.90), smoking (1.97, 1.57-2.47), and reporting no partner in the past 5 years (2.45, 1.67-3.61 vs. 1 partner) but not with HR-HPV (1.35, 0.79-2.31). Lower uptake of HPV catch-up vaccination was associated with increasing area-level deprivation, non-white ethnicity, smoking, and increasing lifetime partners. CONCLUSIONS: Socioeconomic markers and smoking were associated with HR-HPV positivity, nonattendance for cervical screening, and noncompletion of catch-up HPV vaccination. IMPACT: The cervical screening program needs to engage those missing HPV catch-up vaccination to avoid a potential widening of cervical cancer disparities in these cohorts. As some screening nonattenders are at low risk for HR-HPV, tailored approaches may be appropriate to increase screening among higher-risk women.

Confirmatory assays are essential when using molecular testing for Neisseria gonorrhoeae in low-prevalence settings: insights from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3).

OBJECTIVES: To investigate the occurrence of unconfirmed positive gonorrhoea results when using molecular testing within a large population-based survey. DESIGN, SETTING AND PARTICIPANTS: Between 2010 and 2012, we did a probability sample survey of 15,162 men and women aged 16-74 years in Britain. Urine from participants aged 16-44 years reporting ≥1 lifetime sexual partner was tested for Neisseria gonorrhoeae and Chlamydia trachomatis using the Aptima Combo 2 (AC2) assay, with positive or equivocal results confirmed with molecular assays using different nucleic acid targets. RESULTS: A total of 4550 participants aged 16-44 years had urine test results (1885 men; 2665 women). For gonorrhoea, 18 samples initially tested positive and eight were equivocal. Only five out of 26 confirmed, giving a positive predictive value (PPV) for the initial testing of 19% (95% CI 4% to 34%). Most (86% (18/21)) participants with unconfirmed positive results for gonorrhoea reported zero or one sexual partner without condoms in the past year and none had chlamydia co-infection, whereas all five with confirmed gonorrhoea reported at least two recent sexual partners without condoms, and four had chlamydia co-infection. The weighted prevalence for gonorrhoea positivity fell from 0.4% (0.3% to 0.7%) after initial screening to <0.1% (0.0% to 0.1%) after confirmatory testing. By comparison, 103 samples tested positive or equivocal for chlamydia and 98 were confirmed (PPV=95% (91% to 99%)). CONCLUSIONS: We highlight the low PPV for gonorrhoea of an unconfirmed reactive test when deploying molecular testing in a low-prevalence population. Failure to undertake confirmatory testing in low-prevalence settings may lead to inappropriate diagnoses, unnecessary treatment and overestimation of population prevalence.

Prevalence, risk factors, and uptake of interventions for sexually transmitted infections in Britain: findings from the National Surveys of Sexual Attitudes and Lifestyles (Natsal).

BACKGROUND: Population-based estimates of prevalence, risk distribution, and intervention uptake inform delivery of control programmes for sexually transmitted infections (STIs). We undertook the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) after implementation of national sexual health strategies, and describe the epidemiology of four STIs in Britain (England, Scotland, and Wales) and the uptake of interventions. METHODS: Between Sept 6, 2010 and Aug 31, 2012, we did a probability sample survey of 15,162 women and men aged 16-74 years in Britain. Participants were interviewed with computer-assisted face-to-face and self-completion questionnaires. Urine from a sample of participants aged 16-44 years who reported at least one sexual partner over the lifetime was tested for the presence of Chlamydia trachomatis, type-specific human papillomavirus (HPV), Neisseria gonorrhoeae, and HIV antibody. We describe age-specific and sex-specific prevalences of infection and intervention uptake, in relation to demographic and behavioural factors, and explore changes since Natsal-1 (1990-91) and Natsal-2 (1999-2001). FINDINGS: Of 8047 eligible participants invited to provide a urine sample, 4828 (60%) agreed. We excluded 278 samples, leaving 4550 (94%) participants with STI test results. Chlamydia prevalence was 1·5% (95% CI 1·1-2·0) in women and 1·1% (0·7-1·6) in men. Prevalences in individuals aged 16-24 years were 3·1% (2·2-4·3) in women and 2·3% (1·5-3·4) in men. Area-level deprivation and higher numbers of partners, especially without use of condoms, were risk factors. However, 60·4% (45·5-73·7) of chlamydia in women and 43·3% (25·9-62·5) in men was in individuals who had had one partner in the past year. Among sexually active 16-24-year-olds, 54·2% (51·4-56·9) of women and 34·6% (31·8-37·4) of men reported testing for chlamydia in the past year, with testing higher in those with more partners. High-risk HPV was detected in 15·9% (14·4-17·5) of women, similar to in Natsal-2. Coverage of HPV catch-up vaccination was 61·5% (58·2-64·7). Prevalence of HPV types 16 and 18 in women aged 18-20 years was lower in Natsal-3 than Natsal-2 (5·8% [3·9-8·6] vs 11·3% [6·8-18·2]; age-adjusted odds ratio 0·44 [0·21-0·94]). Gonorrhoea (<0·1% prevalence in women and men) and HIV (0·1% prevalence in women and 0·2% in men) were uncommon and restricted to participants with recognised high-risk factors. Since Natsal-2, substantial increases were noted in attendance at sexual health clinics (from 6·7% to 21·4% in women and from 7·7% to 19·6% in men) and HIV testing (from 8·7% to 27·6% in women and from 9·2% to 16·9% in men) in the past 5 years. INTERPRETATION: STIs were distributed heterogeneously, requiring general and infection-specific interventions. Increases in testing and attendance at sexual health clinics, especially in people at highest risk, are encouraging. However, STIs persist both in individuals accessing and those not accessing services. Our findings provide empirical evidence to inform future sexual health interventions and services. FUNDING: Grants from the UK Medical Research Council and the Wellcome Trust, with support from the Economic and Social Research Council and the Department of Health.

Evaluation of strategies for confirming Neisseria gonorrhoeae nucleic acid amplification tests.

The implementation of widespread unselected screening for Neisseria gonorrhoeae in England, using nucleic acid amplification tests (NAATs), has raised concerns regarding the potential increase in misdiagnoses. To increase the positive predictive value, confirmatory testing of positive specimens has been recommended; however, in practice this can be difficult to perform. This study examined the role of two different testing strategies for confirming the N. gonorrhoeae status of specimens that had been examined by the ProbeTec Strand Displacement Amplification (SDA) assay (Becton Dickinson). A total of 227 residual clinical specimens in SDA assay collection tubes were sent for confirmatory testing using two different testing approaches: (i) examination using two in-house real-time PCR assays (opa and porA pseudogene) and (ii) examination using the APTIMA Combo 2 (AC2) assay and the APTIMA Monospecific N. gonorrhoeae (AGC) tests (Gen-Probe). Of the 113 SDA-positive specimens (including low positives) examined, 93 % were confirmed as N. gonorrhoeae-positive using either one or both real-time PCR assays. In contrast, only 34 % were confirmed using the AC2 and/or the AGC assays. All 114 SDA-negative specimens were confirmed as negative using all four confirmatory tests. Clearly the AC2 and AGC assays cannot reliably be used to confirm residual specimens in SDA assay transportation buffers, due to the incompatibility of different platform chemistries. Although high rates of confirmation (93 %) can be achieved when examining residual SDA assay specimens using independent real-time PCR assays, establishing well-validated in-house real-time PCR assays for diagnostic use is a large undertaking for many primary laboratories and so such tests may be better confined to specialist laboratory services.

Still no evidence of new variant Chlamydia trachomatis in England and Wales.

BACKGROUND: New variant Chlamydia trachomatis (nvCT) remains an important public health concern and in 2008 four cases of nvCT were reported in Scotland. The present study set out to determine whether nvCT was present in England and Wales. METHODS: 1054 clinical specimens, which had been confirmed as chlamydia positive (using an nvCT unaffected platform) at nine different diagnostic laboratories throughout England and Wales, were examined for the presence of the 377 bp nvCT deletion. RESULTS: 92% (968/1054) of specimens examined were confirmed as wild-type C. trachomatis. The remaining 86 specimens were found to be untypeable, which was probably due to low levels of DNA. No nvCT specimens were identified. CONCLUSIONS: There is currently no evidence that nvCT is present in England and Wales; however, laboratories using nvCT-affected platform should remain vigilant.