Category: Public health

Trichomonas vaginalis – a neglected STI with major global health implications

Trichomonas vaginalis (TV) is the most prevalent curable sexually transmitted infection (STI) globally. Yet at least 80% of TV infections are asymptomatic, though even asymptomatic infections are a public health concern.

In addition to the risk of transmission to sex partners, TV infection has been associated with as much as a 2.7-fold increase in the risk of HIV acquisition, a 1.3-fold increase in the risk of preterm labour, and a 4.7-fold increase in the risk of pelvic inflammatory disease.

A recent review in the journal Sexually Transmitted Infections (STI) highlights the current knowledge of the global epidemiology of TV infection. These include sex differences in the incidence and prevalence of infection, and the potentially important role of female sex hormones, and the menstrual cycle in mediating TV susceptibility and natural history.

WHO has estimated that over half the 248 million new TV infections each year occur in men. By contrast, 89% of prevalent TV cases are found among women. Biological differences between the sexes contribute to these striking differences between men and women.

There has also been an increased understanding of the mechanisms underlying resistance to metronidazole – the current sole drug available to eradicate the organism.

Recent innovations in detection, including the availability of nucleic acid amplification tests (NAATs), have improved our understanding of the natural history of TV infections. These innovations and our increased understanding of this common sexually transmitted infection should help us combat the global epidemic in TV.

Human papillomavirus may increase acquisition of HIV

Many sexually transmitted infections (STI) such as herpes and other ulcerative STI’s, chlamydia and gonorrhoea have been known to be associated with increased acquisition of HIV.

A recent meta-analysis in the journal Sexually Transmitted Infections suggests that human papillomavirus (HPV) infections, which is associated with genital warts as well as a number of malignancies, may also be associated with sexual transmission of HIV.

Since HPV is the commonest sexually acquired STI, this association, if confirmed, will have important public health consequences. This is particularly true as most sexually acquired HPV infections can be prevented by  vaccinating children.

 

HPV and HIV acquisition
HPV and HIV acquisition

 

 

What is in the May issue of STI

The latest issue of STI (Sexually Transmitted Infections) contains articles on increasing resistance of bacterial STI’s, a successful  educational interventions in South London to encourage HIV testing and data supporting the willingness by a substantial section of men who have sex with men to use pre-exposure prophylaxis for HIV.

particularly worrying is the emergence of a novel strategy by the gonococcus to avoid detection by the now widely used DNA amplification methods.

Non-disclosure of known HIV status in patients visiting a sexually health clinic

Currently in the UK it is estimated that 24%, approximately 22 200 individuals, are unaware of their HIV infection . These data are derived from statistical modelling of many  surveillance, and survey-based data sources. One of the surveillance programmes used is the unlinked anonymous HIV seroprevalence survey, the GUMAnon Survey, where patients who have blood taken at a sexually health clinic would in addition give an additional sample which is tested for HIV after the sample is completely anonymised. The limited information accompanying the sample includes whether the person is known to be HIV positive, has a test in the clinic or refuses an HIV test.

A recent study published in the journal Sexually Transmitted Infections (STI) attempted to identify HIV-infected individuals who attend a genitourinary clinics in the UK aware of their HIV status but fail to tell the clinic they are infected, or on treatment.  In this study in addition to anonymised HIV testing the positive samples had viral load (VL) estimation and after excluding known HIV positives the remaining the samples were analysed for the presence of a panel of antiretroviral drugs.

The authors identified 130 individuals attending a single London sexually transmitted infection clinic in 2009 who refused an HIV test.  Of 28 patients identified by the anonymised test  as being HIV positive who had not admitted to being infected 10 patients underwent a test at the clinic and received a positive test.

The other 18 had  refused an HIV test, although found to be positive by the anonymised test. Thirteen of these (72%, 95% CI: 47% to 90%) had a blood viral load (VL) below detection level  (n=11) or VL <1000 copies/ml (n=2) suggesting they were on antiretroviral treatment. Eight had sufficient blood to undergo antiretroviral testing, and all were positive for the presence of drug; all with therapeutic levels of clinically appropriate combinations.

Thus nearly three quarters of HIV positive patients (72%) who refused an HIV test, and hence would have been considered as not knowing their HIV status, were indeed aware of their status and are on treatment.

These results “presents a number of challenges and dilemmas both for clinics and surveillance systems” says Jackie Cassell, editor of STI journal, who went on to also points out the difficult issues of confidentiality in sexual health services in the age of electronic health records.

Self-taking vaginal sample best test for chlamydia and gonorrhoea in women

The optimal diagnostic sample for Chlamydia trachomatis detection should detect the maximum number of infected people.  In women without symptoms the sample of choice is a self taken vulvovaginal swab, which can be done in the privacy of one’s home. But it is not clear whether a vulvovaginal swab or an endocervical swab is the optimum sample in women with symptoms requiring speculum examination.

A recent study by Sarah Shoeman and colleagues published in the BMJ compared the two sampling methods. They showed that in women attending a sexual health centre vulvovaginal swabs were significantly better at detecting chlamydia infection than endocervical swabs among women with symptoms of a sexually transmitted infection.

In these cases, using endocervical samples rather than vulvovaginal swabs would have missed 9% of infections, or 1 in 11 cases of chlamydia infection

A  parallel  study by the same group showed that self taken vaginal swabs tested by the  Nucleic acid amplification tests (NAATs) which offer increased sensitivity for detecting gonorrhoea, is significantly more sensitive and offers good specificity for detecting gonorrhoea compared with standard gonorrhoea culture methods.

However  confirmation of positive results with a second NAAT is essential in low prevalence populations such as the UK, to avoid false positive results

Women and clinicians can be confident that self taken vulvovaginal swabs are as accurate as clinician performed tests for the detection of chlamydia and gonorrhoea in women without symptoms and should be the test method of choice in asymptomatic women.

HIV treatment of infected partner reduces transmission in heterosexual couples

Based on results of randomised clinical trials the World Health Organization recommends antiretroviral drugs for all HIV infected adults in serodiscordant heterosexual relationships at all stages of the disease. But does this strategy work in real life situations?

A recent study published in the Lancet has for the first time reported that such a public health approach is feasible and the outcomes are sustainable at a large scale and in a developing country setting.

New analyses from China look encouraging, say researchers. Between 2003 and 2011, uninfected partners of treated people were significantly less likely to seroconvert than uninfected partners of untreated people (1.3 infections/100 person years (95% CI 1.2 to 1.3) v 2.6 (2.4 to 2.8)). After adjustments, treatment of infected partners was associated with a 26% reduction in risk of transmission to uninfected partners (hazard ratio 0.74, 0.65 to 0.84).

The analyses compared around 24 000 treated couples with nearly 15 000 untreated couples registered in China’s national HIV epidemiology database.

It is hard to say whether treatment was entirely responsible for reducing transmission, because people who were treated were older, sicker, and may have had less sex, or less risky sex, than those who were not yet treated, says a linked comment by the Lancet

But the findings hint at a direct effect. Treated couples looked better protected, despite the relatively low CD4 counts (and presumably higher viral loads) necessary for treatment in China.

Treatment was associated with lower transmission when HIV had been acquired from a transfusion of blood products (50% of the treated couples) or heterosexual sex, but not when it had been acquired from injecting drugs.

Lancet issue on the state of global health

The Lancet has devoted an entire issue to various aspects of global health. The issue is available free for download.

An edited extract from the executive summary follows:

The Global Burden of Disease Study 2010 (GBD 2010) is the largest ever systematic effort to describe the global distribution and causes of a wide array of major diseases, injuries, and health risk factors.

The results show that infectious diseases, maternal and child illness, and malnutrition now cause fewer deaths and less illness than they did twenty years ago. As a result, fewer children are dying every year, but more young and middle-aged adults are dying and suffering from disease and injury.

Thus non-communicable diseases, such as cancer and heart disease, become the dominant causes of death and disability worldwide.

Since 1970, men and women worldwide have gained slightly more than ten years of life expectancy overall, but they spend more years living with injury and illness.

 

New HIV infection in UK in men who have sex with men exceeds heterosexual transmission after many years

Annual report of HIV infections in the United Kingdom in 2001 published by Health Protection Agency (HPA) show that for the first time in  many years newly diagnosed infections were higher in men who have sex with men (MSM) than transmission through heterosexual intercourse.

By the end of 2011, there were an estimated 96,000 (95% credible interval 90,800 – 102,500) people were living with HIV in the UK. Approximately one quarter (22,600, 24% [19%- 28%]) of these were undiagnosed and unaware of their infection. Fig 1

Fig 1. People infected with HIV at the end of 2011

 

This is an increase from the 91,500 people estimated to have been living with HIV by the end of 2010. The estimated prevalence of HIV in 2011 was 1.5 per 1,000 (1.5-1.6) population of all ages, 2.1 per 1,000 (1.9 – 2.3) men and 1.0 per 1,000 (1.0 – 1.1) women.

The rise in new diagnosis in MSM (Fig 2) is particularly worrying as nearly half the patients (47%) are diagnosed late when their immune system is already compromised increasing the chance of a fatal outcome within one year of diagnosis ten fold. These deaths are totally avoidable with the use of anti-viral therapy early in the infection.

 

Fig 2. New cases of HIV by exposure category

 

STIRF: new projects approved

In this year’s funding round we received six applications. After sending them for external peer review by experts, the Scientific Committee approved two projects for funding in 2013 which was submitted to the Trustees.

Project 1: Chlamydia trachomatisis the most common sexually transmitted infection effecting young people in the UK. It infects one in ten of all women aged 15-25 and can cause serious long term complications such as pelvic inflammatory disease and infertility. According to the Health Protection Agency in 2011 in England and Wales 147,594 infections were diagnosed in 15 to 24 year olds.

Recent evidence for emergence of resistance to the commonly used antibotics used in eradicating chlamydia is very worrying. We are delighted to fund Emma Hathorn as part of a multi-centre study to evaluate the incidence of  chlamydia resistance in people attending a clinic for sexually transmitted infections.

Antimicrobial resistance in Chlamydia trachomatis: is it a reality? STIRF-022

 

Project 2: There is increasing focus on involving patients and what they perceive are their actual needs when delivering clinical services in the NHS. This is particularly important in the fast developing field of HIV where new management strategies and new treatments take place within the background of shrinking funding. These clearly call for new ways of delivering these services more efficiently as well as more effectively. It is with this in mind that STIRF decided to fund the nurse-led project by Lucy Land that is taking steps to objectively define these priorities as seen from the HIV-infected patients perspective.

Development of a weighting scale to evaluate the relative importance of items in a validated HIV patient satisfaction questionnaire. STIRF-020

This study aims to refine a questionnaire they developed and validated with the help of HIV-infected patients to find issues that are more important and therefore need to be prioritised in development of HIV services.

Thanks to all the researchers who submitted and to the reviewers who gave their valuable time for free.

Pre-exposure prophylaxis can be a cost effective addition to other preventative options for men who have sex with men

HIV pre-exposure prophylaxis (PrEP), the use of antiretroviral drugs by uninfected individuals to prevent HIV infection, has demonstrated effectiveness in preventing acquisition in a high-risk population of men who have sex with men (MSM).

Researchers from the Imperial College London have developed a mathematical model representing the HIV epidemic among MSM and transwomen (male-to-female transgender individuals) in Lima, Peru, to investigate how PrEP can be used cost-effectively to prevent HIV infection in such populations.

The study reported that strategic PrEP intervention could be a cost-effective addition to existing HIV prevention strategies for MSM populations.

However, PrEP will not arrest HIV transmission in isolation because of its incomplete effectiveness and dependence on adherence, and because the high cost of programmes limits the coverage levels that could potentially be attained.