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STI prevention and surveillance

Susceptibility of heterosexual sub-Saharan women to HIV could be the result of cervicovaginal microbiome characteristics

30 Jan, 17 | by Leslie Goode, Blogmaster

Could part of the explanation for the apparent susceptibility of sub-Saharan African heterosexual women to HIV infection (eight-fold that of males) lie in the bacterial flora of their female genital tract (FGT)?

Studies published in STI journal have considered the relationship between a certain state of the FGT bacterial microbiome – especially the depletion of lactobacillus (Francis & Grosskurth/STIs) – and the susceptibility to BV (Antonio & Hillier/STIs; Hardy & Crucitti/STIs; Francis & Grosskurth/STIs; Haggerty & Ness/STIs), to pelvic inflammatory disease (Haggerty & Ness/STIs), and to other STIs (Francis & Grosskurth/STIs).  Others have observed the prevalence of Lactobacillus in the healthy FGT microbiome (Madhivanan & Krupp/STIs), and considered the impact on the FGT lining of practices of vaginal douching (Balkus & McClelland/STIs), hormonal contraception (Verwijs & Wijgert/STIs), and sexual debut (Jespers & Crucitti/STIs).

Highly relevant to all these discussions is a recently published study by Gosmann & Anahtar of a prospective cohort of 236 young HIV-negative women participating in the South African Ragon Institute’s FRESH study (Females Rising through Educations, Support and Health) in Kwa-Zulu Natal. The researchers were able to follow up their cohort for a total of 198.2 person-years, in the course of which 31 participants acquired HIV.  The researchers distinguish four ‘cervicotypes’ in respect to FGT bacterial flora; then determine their prevalence along with their association with ‘HIV target cells’ (i.e. activated CD4 T cells expressing the HIV co-receptor CCR5) and HIV acquisition.

The four cervicotypes correspond to the dominance of Lactobacillus crispatus and of Lactobacillus iners (CT1 and CT2, respectively), the preponderance of Gardnerella vaginalis (CT3), and a biome showing a far more diverse range of bacterial types (CT4).  Strikingly, the first two cervicotypes (CT1 and CT2) account for only 10% and 32% of women in the cohort; while, among white women in Western countries, the proportion showing Lactobacillus dominance would be c.90%.  The other 58% fall into the categories of high diversity communities with low Lactobacillus abundance (CT3 and CT4).  More interestingly still, none of the 31 HIV sero-conversions took place among the 10% of women with CT1-type bacterial flora.  Rather, sero-conversions were fairly evenly distributed among the other three cervicotypes, with some diminution of relative incidence in the CT2 category (i.e. nine sero-conversions, as opposed to 10 and 12 in CT3 and CT4 respectively).  Researchers observed a 17-fold increase in HIV target cells in women with a CT4-type cervico-vaginal microbiome as against those with CT1-type, and elevated levels of chemokines MIP-α and MIP-β which attract CCR5 expressing cells in women with diverse FGT bacterial communities.

Sadly, regimens aiming to restore Lactobacillus crispatus dominance (e.g. antibiotics or probiotic vaginal suppositories) show significant recurrence rates.  However, modifiable biological and behavioural factors may play a considerable role on Lactobacillus depletion in sub-Saharan African women (e.g. vaginal washing; antibiotic use; recent Trichomonas and HSV-2).  If so, then, as Baeten & McClelland/STIs point out, this would suggest the possibility of effective intervention strategies to reduce HIV transmission by improving vaginal health.

Fresh WHO guidelines on gonorrhoea management + latest US surveillance data on gonorrhoea resistance

13 Oct, 16 | by Leslie Goode, Blogmaster

The emergence in various locations of resistant strains of Neisseria gonorrhoeae (Ng) is narrowing the therapeutic options. The recent (July 2016) WHO Guidelines, revised from 2003, reflect the concern both to treat effectively and steward our remaining defences against the infection in a globally coordinated manner.  They recommend either dual therapy with either single dose 250g intra-muscular ceftriaxone or 400g oral cefixime combined with 1g oral azithromycin (preferred options), or else single therapy with either ceftriaxone, cefixime or 2g spectinomycin).  The choice between these options will depend on local considerations, including Ng susceptibility data.   In the event of treatment failure following WHO-recommended dual therapy, they recommend any of: 500mg ceftraxone, 800mg cefixime, 240mg gentamicin, or 2g spectinomycin, each of them in combination with 2g azithromycin.

Reported surveillance data for a given location will be crucially important, then, for determining at local level the best options for treatment.  Given the global dimension of the threat, however, this data may also be potential evidence for global trends.  Hence the wider interest of the latest (2014) US surveillance data from the Gonococcal Isolate Surveillance Project (GISP)).  Hitherto, the US picture (as in the UK) has been one of steady progression (2006-2011) in prevalence of Ng isolates exhibiting reduced susceptibility (cefixime: MIC ≥0.25 μg/mL; ceftriaxone: MIC ≥0.125 μg/mL), interrupted by a decline in 2013; this is the pattern both for cefixime (0.1%-1.4%-0.4%) and ceftriaxone (0.1%-0.4%-0.1%) (see also Kirkcaldy & Bolan (STIs)).

So where do the latest (2014) data point? As regards cefixime, to a return to the pre-2013 upward trend, it seems, with prevalence rising once again from 0.4% to 0.8%; with ceftriaxone, to the maintenance of the 2013 prevalence level (0.1%).  Presumably, it is the prevalence levels of ceftriaxone that, in the US, constitute the primary focus of concern – since, as in the UK, that is the drug currently recommended, along with azithromycin, for dual therapy.  (See  Town & Hughes (STI) for  an equivalent report of ceftriaxone resistance in the UK).  But the greatest surprise of the 2016 GISP report is the sudden rise of decreased susceptibility to azithromycin: from 0.6% prevalence of reduced resistance strains (MIC ≥2.0 μg/mL) in 2013 to 2.5% in 2014.  The report comments that the recommended dual therapy with azithromycin is unlikely to be a contributor to this trend – though it is possible, they argue, that the small increase in the azithromycin monotherapy by US STD clinics over the last decade could have had some influence on the prevalence of azithromycin resistant strains.  There is evidence of high or rising levels of azithromycin resistance in other locations (Dillon & Thakur (STIs); Bala & Ramesh (STIs)), including, recently, the UK (Chisholm & Fifer/STIs).

How Mobile Technology Can Lead to Improved Care of STIs – by Julie Potyraj

16 Aug, 16 | by Leslie Goode, Blogmaster

Blog by Julie Potyraj, Community Manager, Milken Institute School of Public Health at The George Washington University

e: jpotyraj@publichealthonline.gwu.edu

As we move into an era where our phones do everything from lowering the temperature in our homes to arranging a ride, it comes as no surprise that these devices also offer a new way to meet and engage with potential sexual partners. Along with the rise in popularity of dating apps, there has been an increase the incidence of sexually transmitted infections. In 2014 the CDC received the highest number of reports in history for chlamydia, syphilis, and gonorrhea in the United States. The challenge is to figure out a way to use technology to safeguard our sexual health in addition to meeting new partners.

In an effort to encourage online daters to get tested, a study published in Sexual Health posted advertisements for free HIV test kits on the dating website Grindr. In exchange for providing personal information about their health status and behaviors, participants received a free test kit. Not only did this intervention encourage HIV testing, but the study also showed an increase in the number of young men seeking treatment. Even a few of the volunteers who helped with the study became aware of their statuses.

The Grindr study shows that the privacy and comforts of home testing can be a desirable alternative to visiting a doctors’ office. Providing this alternative could potentially increase the number of people seeking testing for STIs. Improved testing technology used in tandem with the convenience and range of a mobile device introduces the opportunity to connect huge numbers of people with diagnostic interventions. The more people who get tested, the more data there is available. If this trend continues, we can anticipate an incredible expansion in electronic reporting, STI surveillance, and the use of this data in health informatics.

Mobile technology contributes to the collection of big data, which is defined as complex data sets that are so large that they cannot be evaluated by traditional data management tools. With better surveillance of STIs, medical providers can reach and identify commonly overlooked demographics by tracking trends to improve diagnostic care, interventions, patient outcomes, and cost of care.

More widely available data about STI outbreaks and incidence rates could help health care providers to make more informed medical decisions. For example, a care provider who identifies chlamydia from a patient’s urine could use big data to inform her decision about what type of antibiotic to prescribe. She may find there is an increasing incidence of azithromycin-resistant chlamydia in her city or state. Her awareness of this emerging trend would lead her to prescribe her patient with doxycycline instead; providing better medical care through informed treatment decisions.

The use of mobile technology can broaden epidemiologic surveillance and trend analysis of STI infections, offering knowledge to care providers that is otherwise unobtainable. More people using STI diagnostic interventions leads to the more people being tested and in turn better access to STI statistics. Mobile technologies, and health interventions that make use of them, can contribute to the collection of timely, relevant data. The analysis and interpretation of this data offers the possibility of improving health care quality and outcomes for patients.

Julie Potyraj

UK National Health Service (NHS) kicks PrEP into the long grass

18 Jul, 16 | by Leslie Goode, Blogmaster

A recent BMJ editorial condemns the NHS position that it will not consider PrEP for direct NHS funding.  The decision was first communicated in an NHS statement issued in March, then confirmed by a review on 31st May, following reconsideration in response to objections raised by interested groups.  This brought to an end an eighteen-month process of discussion between Department of Health, doctors and patients groups, Public Health England and other stakeholders.  The NHS decision is currently under judicial review – which no doubt explains the timing of the BMJ editorial.

Advocates of PrEP argue that the NHS has powers under the Health and Social Care Act (2012) directly to commission services ‘prioritized for investment’, and that PrEP should qualify for consideration on this basis.  But the conclusion of the NHS is that PrEP does not qualify to be so considered because the Local Authorities Regulations (2013) clearly stipulate that commissioning for sexual health prevention is legally the responsibility of local government.

Technically, then, the argument turns on whether the NHS can commission for PrEP directly, given that PrEP is a form of sexual health prevention. Needless to say, in the eyes of the advocates of PrEP, this is a mere technicality invoked by the NHS in order to shirk its responsibilities.  The NHS statements also include the proposal to work with local government authorities on exploring how they should go about commissioning PrEP services most effectively, and to dedicate £2m to the establishment of local pilots.  The problem here is that local authorities, having lately had £200m shaved off their funding for sexual health services, are presumably not in a hurry to pick up the tab.

So what about the case for PrEP? As regards effectiveness for high-risk MSM populations, PrEP has emerged with flying colours from recent trials, including the UK PROUD  study (PrEP Highly Effective/STIs/blog; PROUD/STIs/blog) and trials with similar populations undertaken in France (IPERGAY) and California (Volk & Hare).  Cost effectiveness, however, is another matter – and here PrEP has failed to make the grade.  Recent studies have shown that in the UK PrEP is not even borderline cost-effective without substantial reductions in the cost of the drugs (Cambiano & Phillips/STIs; PrEP Highly Effective/STIs/blog; PrEP cost effectiveness study). And, of course, even cost-effectiveness is not the same as affordability.  When it is borne in mind how much in the way of demonstrably very cost effective services have recently been rendered unaffordable by government cuts (Unprotected Nation/Report), the case for PrEP in the present climate does not look strong.

Population-based evidence for the preventative efficacy of quadrivalent HPV in Australia

30 Sep, 14 | by Leslie Goode, Blogmaster

The HPV vaccination programmes introduced by many countries over the last few years (since 2007) reveal considerable diversity in the coverage they have achieved, the mode of access (i.e. school, public health, private clinics) and responsibility for cost (i.e. publically vv. privately funded) – even in Europe (see ECDC Guidance).  In the light of the known efficacy of the vaccine, implementation has seemed frustratingly slow – partly, in some cases, due to ungrounded negative public perceptions around safety (e.g. in Japan where the national programme was actually suspended) and the impact on sexual mores (e.g. in the US).  Early indicators of its positive health impacts in countries like Australia – where implementation was early (2007) and wholehearted – are therefore to be welcomed, as favouring the implementation of programmes in the future.  In the absence of evidence of the reduction of cervical and other cancers, evidence of the effectiveness of the quadrivalent vaccine against warts – from clinics (STI/Donovan & Fairley; STI/Garland & Jayasinghe; STI/Fairley & Bradshaw), or pharmacists (STI/Wilson & Baker) – or evidence for the reduction of cervical abnormalities (STI/blogs/Brogly & Yang) – may offer a proxy.

Smith & Canfell (S&C), recently published in Journal of Infectious Diseases, claim to provide the first whole population analysis of the impact on genital warts of a national HPV vaccination programme – and this may be the best predictor of the longer-term, and more important, cancer prevention benefits to be seen in future years.  It is no surprise it derives from Australia, the first (2007) country to introduce routine school-based vaccination of 12-13 yr girls, plus catch-up through to 2009 for girls 13-17 yrs in schools, and young women 18-26 yrs in primary care. Earlier studies in Australia largely relied on data from sexual health clinics; this study is based on national data of all hospital episodes 1999-2011 involving a diagnosis of genital warts.

The findings of S&C show a decline of 89.9% in admissions involving warts from 2006/7 to 2010/11 for girls aged 12-17 yrs, a decline of 72.7% for women aged 18-26, and a decline of 38% for men aged 18-14 (the indirect effect of female vaccination).  The decline of cases in the 18-28 age group occurs from mid-2008. Other age groups do not show the same sharp decline, nor do MSM – to judge from the fact that the decline exclusively concerns warts in non-anal location.

An issue of particular concern to Australia, and one that consequently receives considerable attention in this study, is the impact on the indigenous population, where incidence and mortality rates for cervical cancer are, respectively, 2.8 and 4.7 times higher for the indigenous as for the non-indigenous population.  Reductions for indigenous and non-indigenous females appear to be similar (86.7% and 76.1% respectively) – which is curious, given that data for two Australian states indicate lower rates of course completion (3 doses) by indigenous females.  If the same tendency in uptake were replicated in the other Australian states (which we don’t know) this might suggest the efficacy of ≤2 dose courses of therapy.  Such a result would corroborate the findings of a recent study covered in this blog (STI/blogs/”Catch up” and incomplete HPV vaccination), which investigates the efficacy of ≤2 dose courses of therapy also in the context of socially disadvantaged groups.

 

IDU and HIV in the Middle East: a brief window of opportunity?

22 Jul, 14 | by Leslie Goode, Blogmaster

There are regions of the world where intravenous drug use (IDU) is known to have a key role in evolving HIV epidemics.  Information about IDU populations, on the basis of which to motivate and inform public health interventions, can be scant and of poor quality (STI/Aceijas & Hickman).  This deficiency is particularly important to address, given the possibility in some contexts of these populations serving as a bridge into other populations (STI/Reza & Blanchard; STI/Decker & Beyrer), and the practicality and cost-effectiveness of interventions that could make a difference (e.g. needle/syringe exchange programmes) (STI/Demyanenko & Vagaitseva; STI/Boci & Hallkaj).

The Middle East and North Africa (MENA) is among the regions of the world in which IDU might be expected to be a key epidemiological factor – given the availability and cheapness of drugs (US$ 4 per gram of heroine, as against US$ 100 in Europe).  But, as recently as 2005, the region was characterized as “as real hole in terms of HIV/AIDS epidemiological data” – let alone in terms of IDU HIV data.  STI/Reza & Blanchard in an alarming study of epidemiological bridging in Pakistan do not include other MENA countries among the epidemiological parallels to which they refer – perhaps because of the lack of data.

A recent systematic review by Mumtaz & Abu-Raddad (M&R) may go some way to addressing this need, but points to the importance of further research.  M&R review and synthesize data from sources (e.g. international and regional databases, and country-level reports) relevant to actual and potential HIV risk for IDU populations across 23 nations in MENA.  They estimate average IDU over the region at 0.24 per 100 adults, and HIV prevalence in these populations averaging 10-15% (both figures comparable with what we find in other regions).  Among the 10 (23) nations for which good evidence is available, 6 show concentrated epidemics suddenly emerging over the last ten years (Iran, Pakistan, Afghanistan, Egypt, Morocco, Libya), at national (Iran, Pakistan) or local (Afghanistan, Egypt, Morocco, Libya) level; 4-5 others show low level epidemics.

This study delivers a strong message.  Data from countries for which there is evidence of low level IDU HIV epidemics suggests “moderate HIV potential” (i.e. high levels of unsafe practices reflected in prevalence of Hepatitis C and other STIs).  The same, for all anyone knows, may also be true for those 13 countries for which the evidence is not available.  Pakistan saw rocketing levels of HIV (from near 0% to 23% in six months) following introduction of the infection into IDU populations.  Low prevalence countries, including those about which we know little, may have only a brief “window of opportunity” before they experience a comparable explosion of HIV among their own IDU populations.  This, according to M&A makes it imperative to conduct studies in those 13 countries, and to implement further rounds of surveillance in those for which there is already evidence, with a view to making timely and effective interventions.  M&A cite, as evidence of the patchy coverage of IDU by existing prevention services over the region, the very small proportion of the IDU population reporting ever being tested for HIV as indicated by studies conducted in Morocco and Pakistan.

Cultural constraints on the uptake of voluntary medical male circumcision in Eastern and Southern Africa

23 Jun, 14 | by Leslie Goode, Blogmaster

My previous blog spoke of the recent PLoS-Medicine Collection on the progress of a UNAIDS initiative for a five-year scale-up of Voluntary Male Medical Circumcision (VMMC) for HIV prevention in 14 high priority Eastern and Southern African countries.  Among the papers, Ashengo & Njeuhmeli (A&N) and Macintyre & Bertrand (M&B) deal with what the authors of the Collection Review identify as one of the two major obstacles to deployment of the initiative: the insufficiency of demand, especially amongst older (aged 25+) men.  They consider the cultural and social constraints on demand, as these are reflected in the very different cultural contexts of Zimbabwe and Tanzania/Iringa Province (A&N) and Kenya/Turkana County (M&B).

In Tanzania, where circumcision as a cultural practice is widespread, A&N’s figures show a proportion of older men presenting for VMMC through to 2013 of c.6%.  Very few of these were reached through campaigns, as opposed to routine services.  In Zimbabwe, by contrast, where circumcision is not widely practised, the proportion of aged 25+ circumcised through the program was c.33%.  There was much less difference in the age profiles of those accessed by campaign and routine service modalities.  Whereas, in Tanzania there is a cultural perception “that male circumcision is most appropriate before or during puberty” (and older men do not come to VMMC services in a setting that includes mostly adolescent clients) – in Zimbabwe there is less difference between age groups, either in respect to numbers circumcised or preferred mode of access.  Intriguingly, this suggests that the existence of a cultural norm of circumcision may be more of an obstacle than an asset where older clients are concerned.  Of course, this contrast has to be set in the context of the overall advantage in terms of HIV/AIDS prevention conferred on countries like Tanzania by the existence of the cultural norm.  On difficulties of demand in Zimbabwe specifically, see STI/Kaufman & Ross.

A further insight into the potentially negative impact of existing cultural practice is cast by M&B.  Focus group discussions and in-depth interviews in the rural, traditionally non-circumcising area of Turkana County, Kenya, draw attention to perceptions of circumcision amongst older men that are not favourable to their widespread up-take, especially by the older age-group.  The first is the identification of circumcision with the cultural values of other (potentially hostile) groups.  Interestingly, the negative impact of the perception of the practice as imposed from outside, or else non-traditional, has been demonstrated in other non-circumcising cultures (STI/David; STI/Madhivanan & Klausner). The second is the understandable perception that HIV/AIDS is a “new” problem among young urban dwellers (most Turkana sufferers belong in this category) and that circumcision, as a response to this “new” problem, is appropriate for the young, not for older, rural people (see also responses in a study on the acceptability of VMMC in Rwanda: STI/Mbabazi).

The impression that emerges from both studies is that the existence of a cultural practice of circumcision amongst certain groups in a region does not always confer an advantage where potential clients for VMMC are in the older age groups (25+).  In particular, good uptake of VMMC services by adolescents may actually prove an obstacle for older men, reinforcing the cultural perception of VMMC as primarily for younger men.  In this situation service providers may face a choice between strategies that yield the greatest number of circumcisions through an exclusive focus on the younger age-group, and strategies designed to attract a wider diversity of age-groups.

 

The roll-out of UNAIDS voluntary medical male circumcision programmes in sub-Saharan Africa: Is it working?

18 Jun, 14 | by Leslie Goode, Blogmaster

Voluntary medical male circumcision (VMMC) has been demonstrated to reduce HIV acquisition by 60% or more.  WHO and UNAIDS have recommended that VMMC form a part of comprehensive HIV prevention programming in regions of high prevalence, such as sub-Saharan Africa.  Mathematical modelling suggests that the achievement of 80% VMMC coverage within 5 years in 14 countries in Eastern and Southern Africa would avert 3.36m new HIV infections. In the light of this the UNAIDS Joint Strategic Action Framework (JSAF) has set out the goal of circumcising 20.2 million men in five years across these countries. The challenges this represents on both the supply and the demand side are comprehensively discussed by STI/Gray & Kigozi.

A recent PLoS – Medicine Collection considers the progress thus far, and through to 2016, of this initiative.  The Collection Review (Sgaier & Njeuhmeli (S&G)) offers a useful survey. The year preceding the JSAF and the first two years of the initiative have seen yearly VMMC of 0.88m, 1.7m, and 2.9m respectively. If we assume current rates of growth, this would give a cumulative total of 17.5m circumcisions by 2016 – about 3m short of the 20.2m target; if we assume no growth, the cumulative total for this period would be 13.7m.  The scale-up of VMMC over the last three years has been impressive. Still, rates of year-on-year growth have fallen from 109% (2011) to 72% (2013).  S&G identify two factors impeding the achievement of the JSAF goal: first, insufficient funding, largely as a result of the failure of international donors to step in alongside the US President’s Emergency Plan for AIDS Relief (PEPFAR) (which currently bears 80% of the cost); second, the lack of – or failure to create – sufficient demand for VMMC in the targeted countries, especially amongst the older element (i.e. aged 25+) of the population.

The 13 papers in the collection deal with issues around supply of VMMC – such as maintaining quality of service during scale-up (Jennings & Njeuhmeli; Rech & Bertrand; Rech & Njeuhmeli) and optimizing efficiency in service delivery (Rech & Njeuhmeli;  Mahvu & Bertrand; Perry & Bertrand).  But, more interestingly, they also deal with the problem that S&G identify as one of the two main obstacles to achieving the JSAF goal – that of creation of demand (Macintyre & Bertrand; Ashengo & Njeuhmeli).  This important issue will be covered in my next blog.

Taking seriously the public health impact of disengagement from HIV care in the US

17 Jun, 13 | by Leslie Goode, Blogmaster

ART as a strategy for “treatment-as-prevention” is frequently acknowledged.  Public health efforts, in the US as elsewhere, have focussed on prompt initiation of ART for the newly-diagnosed so as to shorten the duration of viremia – and thereby also reduce transmission risk.  But what about the public health implications of people living with HIV (PLWH) who have been diagnosed, but are disengaged, or poorly engaged with ART?

Contributions to STIs journal from the UK have discussed disengagement from a clinical perspective, its various social and behavioural concomitants (http://sti.bmj.com/content/early/2013/05/21/sextrans-2012-050966.abstract?sid=a9129e3e-e0b9-4e00-ad11-7023dd74276f; http://sti.bmj.com/content/79/4/349.3.full?sid=a9129e3e-e0b9-4e00-ad11-7023dd74276f).  However, in the US (and no doubt other countries) where the proportion of PLWH with consistently suppressed viral load (VL) is estimated at just 28%, with a large proportion of PLWH lost to follow-up (an estimated 35% in New York City), the public health impact of disengagement also becomes a serious concern.  For a start, the impact of early ART initiation as a “treatment-as-prevention” strategy can only be very limited.

A recent longitudinal study of a New York City (NYC) Health Department intervention to re-engage “persons lost to follow-up” (LTFU), sets out to consider the public health case for deploying resources on the “disengaged”, as well as the “not yet initiated” (http://journals.lww.com/aidsonline/pages/results.aspx?txtKeywords=Udeagu).  Existence of mandatory named HIV and laboratory reporting in NYC makes such an intervention a theoretical possibility. But how useful would surveillance data prove in locating LTFU – and how willing would the LTFU themselves be to re-engage with care?  These were the issues confronting the public health case workers conducting the investigation over the period 2008-2010.

Of the 797 PLWH presumed LTFU 409 (60%) were confirmed LTFU after elimination of those who could not be located, and those who turned out current-to-care after all.  Of these 409, 240 (59%) are classified as having returned to care as a result of the intervention  on the basis of HIV visit confirmed through medical record review or CD4/VL test report; however, most (97%) of the 240 also had at least one CD4 or VL test performed during the 12-months subsequent to their first return-to-care visit.  The returned-to-care group were much more likely to have had CD4/VL reported that those who refused linkage-to-care (95% vs 39%).  More disappointingly – only 65 partners were named in the course of the exercise, and ultimately only 3 newly diagnosed with HIV infection as a direct result of the study intervention.

The most important finding is the willingness of LTFU clients to re-engage with care, and the extent of their successful retention in care after re-engagement.  Other findings relate to the serviceability of the laboratory, surveillance and jurisdictional infrastructure for the purposes of the provision of a more comprehensively “wrap-around” care programs capable of improving retention in care.  Here the issues identified are the timely availability of laboratory information, the potential of linkage between surveillance data and the hospital record system, both of which could have saved expenditure on the location of presumed LTFU who turned out to be “current-to-care”. (The Louisiana Information Public Health Exchange is held up as a potential model of what can be achieved: http://www.lsms.org/site/images/stories/LaPhie-Non-techincal%20Guide.pdf).

What fluidics engineering can do to prevent vertical HIV/syphilis transmission in low resource settings

2 Oct, 11 | by Leslie Goode, Blogmaster

The economic case for investment in the prevention of vertical (mother to child) transmission of HIV and syphilis is easily made – even in low resource settings.  Yet the virtual elimination of maternal HIV transmission remains a goal still to be achieved in many regions, while syphilis in pregnant mothers is often unaddressed with tragic consequences in terms of peri-natal mortality.

The final resolution of these problems will no doubt require a multi-dimensional and holistic approach of the kind recommended by the UNAIDS report.  Yet a recently trialled technology, designed by biomedical engineers from Columbia University, may ease the way to that solution:  it promises to deliver a point-of-care HIV/syphilis test that replicates all the steps of ELISA (enzyme-linked immunosorbent assay), with a sensitivity and specificity to match traditional benchtop assays – but at low cost, with minimal equipment, and requiring no user interpretation (all important considerations in low resource settings).

A recent paper in Nature Medicine describes the technology – the “mChip” assay (mobile microfluidic chip for immunoassay on protein markers), and reports the encouraging results of three trials undertaken in Rwanda.

The device consists in a microfluidic cassette (5.4 cm x 8.5 cm) costing $0.10.  A metal spacer, displacing 6 ml of air in a syringe, is used to draw into the cassette a fluid plug consisting in 14 reagents separated by air spacers.  The procedure produces a signal that can be detected using low cost optics such as light emitting diodes and photodetectors (costing $0.50 and $6.00 respectively).  The test requires less than 1μl of unprocessed whole blood and is complete in 15 minutes.

When tested in Muhima Hospital Kigali on 70 specimens of known HIV status the device demonstrated an overall sensitivity of 100% and a specificity of 96%.  It was also evaluated on 101 archived specimens from couples receiving HIV voluntary counselling, and showed similar levels of sensitivity (100%) and specificity (94%).  Thirdly, the ability of the device to perform a combined HIV-syphilis test was investigated at Project Ubuzima, using 67 serum and plasma samples collected for a separate research study on female sex workers in Kigali.  The duplex test showed sensitivities of 100% and 94% and specificities of 95% and 76% for HIV and syphilis respectively.

A paper covered in a previous blog (Screening for syphilis in pregnancy: evidence for the effectiveness of doing something) reviews the disastrous failure in many low resource contexts to test and treat syphilis in pregnancy.  For all the priority rightly given to the prevention of HIV, the inclusion of syphilis in the duplex test seems a commendable element.

Curtis D Chin et al., “Microfluidics-based diagnostics of infectious diseases in the developing world”, Nature Medicine 17, 1015-1019, 31st July 2011

http://www.nature.com/nm/journal/v17/n8/full/nm.2408.html

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